Constipation & Gastroparesis
This post is for educational purposes only. It is not intended to replace medical advice. Please talk with your doctor or healthcare practitioner about your personal circumstances and what's right for you.
Constipation is one of those topics that people are often uncomfortable bringing up, but if you have gastroparesis, it's a vital part of the conversation. In this post, I want to walk you through what constipation actually means, why it matters so much for those with gastroparesis and — most importantly — what you can do to address it.
What Is Constipation?
Here's something that surprises a lot of people: what’s considered "normal" when it comes to bowel movements varies quite a bit from person to person, so there isn't a single definition for what constitutes “abnormal.” It may be normal for you to have a bowel movement every other day, but for someone else, that would signify constipation.
That said, constipation often looks like:
Fewer than three bowel movements per week
Excessive straining during bowel movements
Stools that are hard, dry, pellet-like, or pebble-like (Types 1 and 2 on the Bristol Stool Scale)
A feeling of incomplete evacuation
Feeling like there's a blockage that's preventing you from emptying your bowel
Because regularity is so individual, the most important thing is to pay attention to changes in your own pattern. If something is new or different for you over time, that's worth talking to your doctor about.
Red Flag Symptoms
If you experience any of the following, contact your doctor, as these symptoms can sometimes signal an acute or more serious issue:
Sudden, intense abdominal pain
Blood in your stool
Pencil-thin stools (these can indicate a structural issue)
New or rapidly worsening constipation that doesn't respond to your usual approaches
Constipation & Gastroparesis
Being constipated is uncomfortable, and that alone is a good enough reason to address it. But for people with gastroparesis, it goes beyond that. I think many people don't realize just how much their constipation may be affecting the rest of their GI symptoms.
Constipation worsens gastroparesis symptoms. Fullness, nausea, bloating, pain — these can all be amplified by constipation. If you're doing everything “right” in terms of managing your GP and you're still struggling with symptoms, unaddressed constipation could be part of the reason.
Constipation can actually slow gastric emptying. My motility specialist shared a study with me years ago that I've never forgotten. Researchers took a group of medical students — all with normal gastric emptying times — and intentionally made them constipated. After a period of time, they repeated gastric emptying scans and found a measurable delay in gastric emptying in people who had previously been completely normal.
Think about it this way: if you had a tube and you plugged the bottom so nothing could come out, eventually you wouldn't be able to put anything in from the top either. The gut is remarkably intelligent. The nerves inside it communicate not just with the brain, but with each other. When you're constipated, signals travel from the colon to the brain and back to the stomach, essentially saying, slow things down up here because nothing is moving down there. So your already-delayed stomach empties even more slowly.
Constipation sets the stage for bacterial overgrowth. I'll talk more about this at the end of this post, but chronic constipation can contribute to an overgrowth of bacteria and other microorganisms in the gut, which brings its own set of symptoms that can look a lot like gastroparesis.
The bottom line: managing constipation isn't just about comfort. It's a core part of managing gastroparesis.
What's Causing It?
For the majority of people with gastroparesis, constipation isn't a sign that your motility issues have spread throughout your entire GI tract. I want to emphasize that, because it can be really scary to develop constipation when you already have a motility disorder and assume the worst. In most cases, constipation is caused by a combination of factors that are specific to living with gastroparesis — and that means they're often reversible. Let's walk through the most common ones.
Insufficient Fluid Intake
I use the term "insufficient fluid intake” rather than "dehydration" because even mild, chronic under-hydration is enough to cause or worsen constipation over time. Your colon depends on adequate fluid to keep stool soft and moving. When your body doesn't have enough fluid overall, the colon compensates by pulling more water out of the stool — leaving it hard, dry, and difficult to pass.
Often, people with gastroparesis limit water and other liquids because they lead to increased fullness or other symptoms. And if you experience vomiting, you’re losing fluid regularly that may be difficult to adequately replace.
The Gastroparesis Diet
The gastroparesis-friendly diet, by design, is low in fiber. And while that helps reduce the symptoms associated with delayed gastric emptying, it also creates the perfect conditions for constipation. Fiber is essential for bowel regularity. It adds bulk to stool and helps move things through the colon. If we restrict fiber too much, it makes it very difficult to maintain bowel regularity.
What’s more, a typical GP-friendly diet tends to be heavy on dry, refined carbohydrates and often includes a lot of low-fat dairy. These types of foods can also contribute to constipation, and when they make up a large portion of your diet day after day, the overall effect can be significant.
A typical gastroparesis-friendly diet combined with insufficient fluids is, unfortunately, a reliable recipe for constipation.
Medications
This is one that a lot of people overlook. Several medications commonly used to manage gastroparesis symptoms can contribute to constipation:
Zofran (ondansetron) and other antiemetics — often taken daily for nausea, and constipation is a known side effect
Narcotic/opioid pain medications — notoriously constipating; more on this in the treatment section
Certain antidepressants, particularly tricyclic antidepressants sometimes used for gut pain or motility
Antispasmodics — sometimes prescribed when IBS is in the picture
Aluminum- or calcium-based antacids — frequently constipating, especially with regular use
If you're taking any of these medications and struggling with constipation, that's a conversation to have with your doctor. There may be alternatives, or there may be strategies to manage the constipation as a side effect.
Physical Inactivity
Your colon is a muscle, and like all muscles, it benefits from movement. Physical activity stimulates the natural contractions that move stool through the colon. Many people with gastroparesis are physically inactive for a variety of reasons — fear of weight loss, concern about worsening symptoms, fatigue — and this can be a real contributor to constipation.
The Underlying Cause of Your Gastroparesis
In some cases, whatever is causing the gastroparesis is also affecting the rest of the GI tract. Conditions like scleroderma and hypothyroidism, for example, cause constipation in addition to gastroparesis. Some people have slow motility throughout the entire GI tract for no identifiable reason (idiopathic). A smaller number of people have conditions like chronic intestinal pseudo-obstruction or colonic inertia, which involve slow motility specifically in the lower GI tract.
But I want to reiterate: for most people with gastroparesis, constipation is far more likely to be a combination of the dietary, lifestyle, and medication factors above than a result of a diffuse motility disorder.
Pelvic Floor Dysfunction
This is one that often goes unrecognized. The muscles of the pelvic floor play a direct role in bowel movements. They need to relax in order to allow stool to pass. In pelvic floor dysfunction, those muscles either don't coordinate properly or actually tighten when they should be relaxing. This isn't something you're doing consciously; it's a neuromuscular dysfunction.
The good news is that it's treatable. Biofeedback is highly effective for this — I'll talk more about it in the complementary therapies section.
Testing & Diagnosis
For most people with gastroparesis, the cause of constipation will be identifiable from a thorough history and the lifestyle/dietary factors we discussed. Formal testing is often unnecessary unless things aren't responding to treatment or there are more complex issues at play. If further evaluation is required, there are several possible tests a doctor might recommend.
Barium X-ray / barium enema: Looks at the physical structure of the colon and rectal area. Helps identify structural abnormalities or obstructions.
Sigmoidoscopy or colonoscopy: A colonoscopy looks at the entire colon with a camera; a sigmoidoscopy looks at just the lower portion. These are used to rule out structural issues like polyps, ulcers, inflammation, or colon cancer. If you're experiencing new constipation, especially with red flag symptoms, your doctor may recommend one of these.
High-resolution anorectal manometry: This test measures pressure within the anal canal and rectum and evaluates how well the muscles coordinate during a bowel movement. It's particularly useful for identifying pelvic floor dysfunction. The balloon expulsion test — where you're asked to expel a small water-filled balloon — is often done alongside it as a simpler screening tool for dyssynergia.
Sitz marker study: You swallow a capsule containing tiny pellets that show up on X-ray. After a set number of days (usually three to five), an X-ray shows how many pellets remain and where they are in the colon. This gives information about transit time and can help identify slow transit constipation or pelvic floor issues depending on where the pellets are concentrated.
Wireless motility capsule: Historically, this test gave a complete picture of whole-gut transit by tracking a capsule's path through the digestive tract. While the widely used SmartPill capsule was discontinued by its manufacturer, some specialized centers use alternative transit studies or are adopting newer wireless tracking technologies currently entering the field to measure regional transit times without radiation.
Treatment: Diet and Lifestyle
I want to start here because for the vast majority of people with gastroparesis, this is where the biggest difference can be made. As the saying goes, when you know better, you do better. So let's talk about what we can do better.
Drink More Fluids, More Consistently
Be sure you’re drinking an adequate amount of liquid every day. Keep in mind that gulping down a big glass of water is likely to make you feel overly full, nauseous, or otherwise symptomatic. Instead, I recommend taking small sips from a water bottle consistently throughout the day. If you tolerate plain water, that’s ideal. Otherwise, diluted fruit/vegetable juice, electrolyte solutions, nutrition drinks, and broth are all good options. Some people find consuming warm liquids — such as tea or coffee — first thing in the morning helps to stimulate a bowel movement.
Slowly Increase Fiber — the Right Kind
The goal for most gastroparesis-friendly diets in terms of fiber intake is typically around 12 to 15 grams per day, depending on individual tolerances. Some people can tolerate a bit more than that. It’s okay to experiment with the amount of fiber that you eat, increasing it slowly — especially if you’re closer to 10 grams or less — so long as it’s not exacerbating your symptoms.
One important distinction that doesn't get talked about enough: soluble and insoluble fiber are not the same thing. This matters when we’re talking about a gastroparesis-friendly diet.
Insoluble fiber: adds bulk and speeds transit through the intestines. Counterintuitively, it's also the type most likely to slow down gastric emptying. That’s because the stomach needs to grind food into very small particles (roughly 1–2mm) before it can pass through the pylorus into the small intestine, and insoluble fiber is especially difficult for a slow or weak stomach to break down. Insoluble fiber is generally best limited in a GP-friendly diet.
Foods high in insoluble fiber include nuts, seeds, peels, whole grains, stringy vegetables, and leafy greens.
Soluble fiber: dissolves in water, forms a soft gel, and is generally better tolerated by those with gastroparesis.
Foods that are high in soluble fiber that can be incorporated into a gastroparesis-friendly diet include: quick oats (not steel cut), ripe bananas, peeled and cooked apples/pears/peaches, peeled root vegetables. Serving size is important here — you may do fine with ½ cup of oatmeal, but a full bowl of oatmeal is likely to leave you feeling symptomatic. The general guidelines of eating for gastroparesis still apply.
Keep in mind that soluble fiber works like a sponge—it requires water to turn into that smooth, stool-softening gel. If you increase your soluble fiber intake without increasing your fluid intake, that sponge will absorb whatever little moisture is left in the gut and can actually worsen constipation. Hydration and fiber must go together.
Particle size can be a helpful distinction here, too. Boiling, steaming, mashing, pureeing, and blending all help break down fiber in ways that can help it empty from the stomach more quickly. Foods that can be more easily reduced to very small particle sizes by these preparation methods — for example, root vegetables like carrots, potatoes, sweet potatoes, turnips, and parsnips — tend to be especially well-tolerated and good for bowel regularity.
It’s worth noting here that this doesn’t necessarily mean adding more food into your diet. It’s really about replacing some of the lower-fiber foods that may be contributing to constipation (white bread, crackers, frozen yogurt, pudding, cheese, etc) with GP-friendly, higher-fiber, more nutrient-rich options.
And a word about bulk-forming fiber supplements like Metamucil and FiberCon: these are generally not appropriate for people with gastroparesis and should be avoided unless your gastroenterologist specifically recommends one for your situation.
Increase Physical Activity
Movement stimulates the natural contractions of the colon, and over time, consistent physical activity can make a significant difference in bowel regularity. Aim to include 30 minutes of mild to moderate physical activity per day. Do whatever type of movement is tolerable and accessible to you — walking, swimming, gentle cycling. If you are currently sedentary, starting with just 10 minutes can help. Avoid high-intensity exercise, which can worsen gastroparesis symptoms and direct blood flow away from the gut (not helpful for alleviating constipation!).
Go When You Need to Go
When managing constipation, it's important that you don't ignore the urge to have a bowel movement. Doing so is problematic for two reasons. First, ignoring the urge can disrupt signaling over time — the rectum stops sending as strong a signal, and what was once a clear cue becomes easier to miss or override. Second, when you don't move stool out of a full colon, fluid gets reabsorbed while it sits there, making it harder, drier, and more difficult to pass later on.
Your best natural window for a bowel movement is typically in the morning and in the 30 to 60 minutes after eating — this is the gastrocolic reflex, the colon's natural wave of activity triggered by food entering the digestive system. If you feel the urge during this window, prioritize it. Don't push through it to finish something else.
For people whose signaling has already been disrupted — which is common after years of chronic constipation — scheduled bathroom attempts can help retrain the bowel. The basic approach is simple: sit on the toilet at the same time each day, ideally 20 to 30 minutes after your largest meal when the gastrocolic reflex is strongest, for 5 to 10 minutes. You're not forcing anything; you're giving your body a consistent opportunity and over time reinforcing the signal.
It's also important to be aware of something called paradoxical diarrhea. In cases of chronic constipation, liquid stool can bypass hard, impacted stool higher up in the colon, and people sometimes mistake this for ordinary diarrhea. If you reach for an anti-diarrheal medication like loperamide (Imodium) in this situation, you'll worsen the underlying impaction — the opposite of what you need. If you're experiencing what looks like diarrhea alongside other signs of constipation, or alternating between the two, talk to your gastroenterologist before treating it.
Try a Footstool
Posture during a bowel movement matters more than most people realize. Elevating your feet on a step stool — so your knees are higher than your hips — mimics a squatting position and relaxes the puborectalis muscle, which reduces the resistance stool has to overcome on the way out. You can find a variety of “toilet stools” on Amazon for around $25.
Magnesium Supplementation
Magnesium is a natural laxative, which is sometimes a side effect people notice when they start taking it for other things like muscle cramps, restless leg syndrome, or headaches. But for constipation, this can be used intentionally. A reasonable starting point for most people is around 200 to 400 mg per day. Start at the low end and increase slowly based on how your body responds. If you feel you need more than 400 mg to get results, talk with your doctor first.
One important note: people with kidney disease should talk to their doctor before supplementing with magnesium. The kidneys are responsible for clearing excess magnesium from the body, and impaired kidney function can allow it to build up to unsafe levels.
Not all magnesium supplements are the same:
Magnesium oxide is the form most specifically targeted at a laxative effect. It's poorly absorbed and moves quickly through the GI tract, which is the point — but that same mechanism tends to cause gas, cramping, nausea, or discomfort for many people. It's also available as magnesium hydroxide, better known as Milk of Magnesia, which works the same way and is a common OTC option many people already have at home.
Magnesium citrate (in capsule or tablet form — not the large bottle of liquid, which is a high-dose laxative prep used for colonoscopy prep and similar situations) is a good middle ground. It's better absorbed and therefore tends to be easier on the GI tract, while still supporting bowel regularity.
Magnesium glycinate and magnesium malate are the most gently absorbed and well-tolerated forms, making them a good choice if you're primarily taking magnesium for non-GI reasons like sleep or muscle cramps, but they're generally less effective for constipation.
Over-the-Counter Laxative Options
If you've made ongoing efforts at the diet and lifestyle changes above and you're still struggling with constipation, there are over-the-counter laxatives available that may help. Here's a breakdown of the main categories and how they relate to gastroparesis:
Stool Softeners
Products like docusate sodium (Colace) do exactly what the name says: they soften stool. They're gentle and generally well-tolerated, and some people find them helpful when their primary issue is hard, dry stools. That said, it's worth knowing that the evidence for their effectiveness is weaker than their popularity suggests — multiple reviews and clinical guidelines have found them to be only marginally effective or no more effective than placebo for constipation in many people. They're unlikely to cause harm, but if you've been taking Colace without much result, that's consistent with the research.
Osmotic Laxatives
These are often the most commonly recommended category for those with gastroparesis. These products work by drawing water into the colon. More fluid in the colon means the muscles have more to work with — think of how much easier it is to squeeze toothpaste out of a full tube versus a nearly empty one.
MiraLAX (polyethylene glycol, or PEG) in particular is considered one of the safer options for daily or regular use. That said, it doesn't work for everyone with gastroparesis — some people find it increases bloating, gas, or nausea without much improvement in bowel movements. If that's your experience, it's worth letting your doctor know rather than pushing through, because that response can be a clue that a different approach is needed.
Lactulose is another osmotic laxative you may encounter as a recommendation from your doctor. It works similarly to MiraLAX but tends to cause more gas and bloating as a side effect, which makes it generally less ideal for those with gastroparesis. If your doctor suggests it, it's reasonable to ask whether PEG might be a better starting point.
Stimulant Laxatives
Senna (Senokot, Smooth Move tea) and bisacodyl (Dulcolax) work by triggering contractions in the colon muscles. They're more potent than osmotic laxatives and come with more potential side effects: cramping, nausea, bloating, and pain. But for some people, they are a necessary and effective treatment option.
One thing worth clarifying here: you may have heard that long-term use of stimulant laxatives damages the colon or creates permanent dependency. This was a concern that circulated for years, but more recent research has largely walked back those claims. The evidence for "cathartic colon" from stimulant laxative use isn't strong. That said, if you find yourself needing stimulant laxatives regularly in order to have any bowel movement at all, that's an important conversation to have with your doctor, because it may suggest an underlying motility issue in the colon that needs evaluation.
Rectal Options
Suppositories and enemas are worth knowing about, especially if vomiting makes it difficult to keep oral medications down. Because they're not absorbed through the digestive tract, they work more quickly and directly on the lower colon and rectum. They can be more reliable for some people for that reason.
If you're starting with rectal options,glycerin suppositories are generally the gentler first step. They work osmotically — drawing water into the rectum to soften stool and stimulate movement — and are widely available OTC without the stronger stimulant effect of bisacodyl.
Bisacodyl suppositories are the more potent option and appropriate when a gentler approach hasn't been sufficient.
For more significant situations where suppositories haven't produced results, a saline enema(such as a Fleet enema) is an OTC option worth knowing about. This isn't something for routine use, but it can be appropriate when stool is more impacted and other options haven't worked. Talk to your doctor before using enemas regularly.
A Note on Laxative Safety
Whichever laxatives you use, your doctor needs to know — both that you're taking them and that you need them. Prolonged laxative use can lead to electrolyte imbalances (which affect heart rhythm, nerve function, and muscle contractions), and some laxatives can interfere with the absorption of medications including blood thinners and certain heart medications. Stimulant laxatives in particular can impair nutrient absorption if things are moving through too quickly. These aren't reasons to avoid laxatives when you need them, but they are reasons to use them thoughtfully and under your doctor's awareness.
Prescription Medications
If lifestyle changes and over-the-counter options haven't been adequate, there are several prescription medications available that you can discuss with your gastroenterologist. This landscape has actually changed quite a bit in recent years, so if you were told some time ago that there weren't many options, it's worth revisiting the conversation.
Lubiprostone (Amitiza): This has been available for a while and works by activating channels in the intestinal lining that increase fluid secretion into the gut. It's effective for many people, but nausea is a common and sometimes significant side effect, which makes it hard for some people with gastroparesis to tolerate.
Linaclotide (Linzess): Available since 2012 and now well-established, linaclotide is a guanylate cyclase-C agonist — a more technical way of saying it works locally in the intestines to increase fluid secretion and improve motility. It's generally well-tolerated compared to some older options. The most important side effect to know about is diarrhea, which may be mitigated by starting a lower dose and increasing slowly.
Plecanatide (Trulance): In the same class as linaclotide and approved in 2017, plecanatide works similarly but has a slightly different mechanism. As with linaclotide, diarrhea is the primary side effect to watch for. Some people who don't tolerate linaclotide well find plecanatide easier to manage, and vice versa — if one doesn't work for you, it's worth asking about the other.
Prucalopride (Motegrity): This drug is particularly relevant to those struggling with both constipation and gastroparesis. It works by promoting coordinated contractions throughout the entire GI tract — including the stomach — meaning it can help both gastric and intestinal motility.
It's been available in Europe for years under the name Resolor and has a strong evidence base. It was FDA-approved in the US in December 2018 for chronic idiopathic constipation and is frequently used “off-label” for gastroparesis, as well. It's generally well-tolerated, with the most common side effects being headache, nausea, and diarrhea. If you've tried other options without success, prucalopride is worth asking your gastroenterologist about.
Tenapanor (Ibsrela): Approved in 2019 for constipation-predominant IBS, tenapanor works through a completely different mechanism — it reduces sodium absorption in the intestine, which causes water to be retained there, softening stool and improving transit.
For opioid-induced constipation specifically: If your constipation is primarily related to opioid or narcotic pain medications, there is now an entire class of medications designed specifically for this situation. Called peripherally acting mu-opioid receptor antagonists (PAMORAs), these include methylnaltrexone (Relistor), naloxegol (Movantik), and naldemedine (Symproic). They block opioid receptors in the gut specifically, without crossing into the brain — meaning they can relieve the constipation caused by narcotic pain medication without affecting your pain control. It’s important to note, however, that these drugs do not appear to negate the effect that opioids have on gastric emptying. For those with gastroparesis, they further delay gastric emptying and are still best avoided whenever possible.
Complementary Therapies
Complementary therapies tend to work best alongside — not instead of — the other things we've talked about. They can meaningfully enhance the effectiveness of dietary and lifestyle changes, and can even complement medication. Here are the ones that appear to be most helpful for constipation in the context of gastroparesis:
Acupuncture: Acupuncture has a legitimate evidence base for functional GI disorders, and for constipation specifically, the research is fairly robust. Systematic reviews have found it beneficial for chronic functional constipation, with improvements in bowel movement frequency, stool consistency, and quality of life.
The mechanism isn't fully understood, but the leading explanation involves the gut-brain axis and the autonomic nervous system. Acupuncture may also influence serotonin signaling in the gut, which plays a significant role in regulating motility throughout the digestive tract. Many people with gastroparesis who try acupuncture for their upper GI symptoms find it unexpectedly helpful for constipation as well, or vice versa.
Abdominal massage: There are specific techniques for massaging the abdomen that follow the path of the colon — up the right side (ascending colon), across the top (transverse colon), and down the left side (descending colon). Done regularly, this can help stimulate movement of stool through the colon. A massage therapist, acupuncturist, or other bodywork practitioner can show you how to do this correctly so you can practice at home, or you can find tutorials online. Note: avoid abdominal massage if you are pregnant.
Gut-directed hypnotherapy: The evidence for this has grown considerably in recent years. Gut-directed hypnotherapy is different from stage hypnosis — it's a therapeutic technique, typically delivered by a trained psychologist or therapist, that directly targets gut-brain communication. It has strong clinical trial support for functional GI disorders broadly, including constipation and motility issues in the lower GI tract. It's more accessible than it used to be, including through some digital programs, such as the Nerva app.
Probiotics: Probiotics are widely used and recommended for constipation, and the evidence for certain strains is fairly good. The effects are strain-specific, however, meaning not all probiotic products work the same. The most important caveat for those with gastroparesis is that probiotics can worsen bloating, gas, and pain in some people. If you want to try them, starting with a low dose of a well-studied strain, like Bifidobacterium, and keeping track of how you feel is the best approach. If bloating or nausea increases, they may not be the right fit for you.
Pelvic floor physical therapy and biofeedback: If pelvic floor dysfunction is contributing to your constipation, physical therapy can be highly effective. If your experience of constipation involves significant straining with little result, a feeling of incomplete evacuation, a sense of blockage rather than simply an absence of urge, or needing to manually assist, those are signs that the muscles involved in evacuation may not be coordinating correctly. That's often a pelvic floor problem, not just a motility problem, and it often responds well to this kind of therapy.
Biofeedback therapy is often delivered alongside pelvic floor PT and is specifically recommended when there is “dyssynergic defecation” — a pattern where the pelvic floor muscles contract rather than relax during a bowel movement. Through biofeedback, you learn to retrain that response using feedback from sensors that show you what your muscles are actually doing in real time. Both pelvic floor PT and biofeedback have become more available at PT clinics and specialty GI centers.
SIBO & IMO
Our understanding of how the overall gut microbiome affects GI motility has grown enormously in the past decade. Dysbiosis — an imbalance in the gut microbial community — can affect bowel function through multiple pathways, including changes in short-chain fatty acid production, alterations in bile acid metabolism, and direct effects on gut motility signaling.
What Is SIBO?
SIBO has become an increasing topic of conversation among those with gastroparesis, so it's important to understand what it means — and why people with GP may be particularly susceptible to it.
Small intestinal bacterial overgrowth (SIBO) refers to an excess of bacteria in the small intestine. Most bacteria in the gut should be in the large intestine, with the small intestine remaining relatively low in bacterial population. When bacteria proliferate there beyond normal levels, it can cause a variety of symptoms including bloating, gas, abdominal pain, and diarrhea.
The gastroparesis connection is important here. Between meals, the small intestine is meant to run what's sometimes called a "housekeeping wave" — a sweeping pattern of contractions called the migrating motor complex (MMC) that keeps bacteria from accumulating where they shouldn't. In gastroparesis, impaired motility disrupts this process, which is why people with GP are at higher risk for SIBO than the general population.
Constipation specifically is more associated with a related but distinct condition called intestinal methanogen overgrowth (IMO), in which the overgrowth involves methane-producing archaea rather than bacteria. This distinction matters both for understanding your symptoms and for treatment, which is why IMO is worth understanding separately.
Hydrogen, Methane, and Hydrogen Sulfide
SIBO isn't a single condition. There are now three recognized types, and they behave differently:
Hydrogen-dominant SIBO is most commonly associated with diarrhea, bloating, and abdominal pain.
Methane-dominant SIBO, now more accurately called Intestinal Methanogen Overgrowth (IMO) and considered a distinct condition, is the type most strongly associated with constipation, bloating, and abdominal distention. Here's something interesting: the methane-producing organisms involved aren't actually bacteria at all — they're archaea (a different domain of microorganisms). Methane gas has been shown to slow intestinal motility, which is why IMO tends to manifest as constipation.
Hydrogen sulfide-dominant SIBO is the newest recognized type, typically associated with diarrhea, stomach pain, severe bloating, and "rotten egg" smelling gas or burps. It is still being studied in terms of optimal diagnosis and treatment.
Should You Get Tested for SIBO/IMO?
If you've addressed the dietary and lifestyle factors we've discussed and you're still dealing with significant constipation — especially if it developed or worsened after your gastroparesis diagnosis — SIBO or IMO is worth raising with your gastroenterologist. The same applies if you're experiencing bloating that worsens throughout the day or after eating and isn't responding to your usual GP management strategies. Because many people with gastroparesis experience bloating as a baseline symptom, it's easy to dismiss, but new or worsening bloating that behaves differently from your typical symptoms is worth paying attention to.
Testing for SIBO/IMO is done via a breath test, which measures the gases produced by bacteria and archaea in the gut. A comprehensive breath test measures both hydrogen and methane — hydrogen elevation is associated with SIBO, while methane elevation points toward IMO. This distinction matters because treatment differs depending on which you're dealing with. When discussing testing with your doctor, it's important to ask about a test that measures both gases rather than hydrogen alone.
One important limitation to be aware of: breath tests are the standard diagnostic tool, but they are imperfect, and false negatives are not uncommon, especially in the context of gastroparesis. You have to ensure that the test allows enough time for the testing substrate to get to your small intestine given the delay in gastric emptying. A negative test does not always mean that you don’t have SIBO/IMO. If your test comes back negative but your symptoms remain, it’s worth a follow-up with a SIBO-experienced gastroenterologist.
Key Takeaways
Constipation is more than uncomfortable — it can exacerbate every symptom associated with gastroparesis, including nausea, bloating, and fullness, and it can actually further delay gastric emptying.
For most people with gastroparesis, constipation is caused by a combination of the GP diet, insufficient fluids, physical inactivity, and medications — not by a separate motility disorder throughout the colon. That's actually good news, because it means those factors can be more readily addressed.
Start with the basics. Increase fluid intake throughout the day, slowly work toward 12–15 grams of mostly soluble fiber per day, reduce dairy and dry, “white” foods, increase consistent moderate physical activity, never ignore the urge to go, and try a footstool.
Magnesium supplementation can be a gentle and helpful addition.
There are more over-the-counter and prescription options than ever, including newer medications like prucalopride (Motegrity), which can help both gastroparesis and constipation.
Complementary therapies often have strong evidence and are worth including in your overall approach.
If you've addressed the basics and constipation persists, consider SIBO or Intestinal Methanogen Overgrowth as a potential contributor and ask your doctor about breath testing.
Always keep your doctor in the loop about any laxatives, supplements, or medications you're taking or considering for constipation. Laxatives can interact with other medications and cause electrolyte imbalances if used without awareness.