- Constipation affects 10–25% of patients on GLP-1 medications and is caused by slowed GI motility
- Hydration and fiber are the most effective first-line solutions
- Most patients find constipation manageable with dietary adjustments
- Contact your provider if you go 3+ days without a bowel movement
Constipation is one of the most common gastrointestinal side effects reported by patients on GLP-1 receptor agonists such as semaglutide (Wegovy, Ozempic) and tirzepatide (Zepbound, Mounjaro). In clinical trials, it is the second most frequently reported GI side effect after nausea. The good news: it is almost always manageable, and there are straightforward steps you can take to prevent and relieve it.
This guide explains why constipation happens on these medications, provides eight practical solutions, and clarifies when you should talk to your provider.
Why GLP-1 medications cause constipation
GLP-1 receptor agonists work in part by slowing gastric emptying — the rate at which food moves from your stomach into your small intestine. This is one of the mechanisms that helps reduce appetite and promote weight loss. However, this slower motility does not stop at the stomach. It affects the entire gastrointestinal tract, including the colon, where water is reabsorbed from stool. When transit time increases, more water is absorbed and stool becomes harder and more difficult to pass.
There are three primary reasons GLP-1 medications contribute to constipation:
- Delayed gastric emptying slows the entire GI tract. The same mechanism that reduces appetite also reduces the speed at which waste moves through your intestines. Slower transit means harder, drier stool.
- Reduced food intake means less fiber. When you eat significantly less food, you are also consuming less dietary fiber — the primary driver of healthy bowel movements. Less bulk in the colon means less stimulation for the muscles that move waste forward.
- Dehydration from eating and drinking less. Many patients on GLP-1 medications do not feel as thirsty and naturally drink less water. Combined with reduced food intake (which also contains water), overall hydration drops — and dehydration is one of the most common causes of constipation.
Constipation on GLP-1 medications is not a sign that something is wrong. It is a predictable consequence of how these medications work — and it is manageable.
How common is it?
In clinical trials for semaglutide and tirzepatide, constipation was reported by approximately 10–25% of patients, depending on the specific medication and dose. This makes it the second most common gastrointestinal side effect after nausea.
For most patients, constipation is mild to moderate. It tends to be most noticeable during dose titration — the period when your dose is being gradually increased — and often improves as your body adjusts to the medication over several weeks.
10–25% of patients in clinical trials reported constipation as a side effect.
Second most common GI side effect, after nausea.
Most common during dose increases and the first few weeks of treatment.
Usually improves as the body adjusts, typically within weeks to a few months.
8 solutions that work
a. Increase fiber gradually
Fiber is the single most important dietary factor for preventing and relieving constipation. It adds bulk to your stool and helps move waste through the colon. However, increasing fiber too quickly can cause bloating and gas, so add it gradually over the course of 1–2 weeks.
Good sources of fiber include vegetables (broccoli, Brussels sprouts, carrots), fruits (berries, pears, apples with skin), legumes (lentils, chickpeas, black beans), and whole grains (oats, quinoa, whole wheat bread). Aim for 25–30 grams of fiber per day.
b. Hydrate consistently
Aim for 64–80 ounces of water per day (8–10 cups). This is critical when you are on a GLP-1 medication because your reduced appetite often means you are drinking less without realizing it. Water keeps stool soft and easier to pass.
- Carry a water bottle and sip throughout the day.
- Set reminders if you are not naturally feeling thirsty.
- Warm water or herbal tea in the morning can stimulate bowel activity.
- Avoid excessive caffeine, which can be dehydrating.
c. Magnesium supplementation
Magnesium draws water into the intestines and can soften stool naturally. Magnesium citrate and magnesium oxide are the forms most commonly used for constipation. However, magnesium can interact with other medications and is not appropriate for everyone — discuss supplementation with your PEAK care team before starting.
Magnesium supplementation can be very effective for constipation, but the right form and dose depend on your individual health profile. Your PEAK clinician can recommend whether magnesium is appropriate for you and suggest the right dosage.
d. Fiber supplement (psyllium husk)
If you are struggling to get enough fiber from food alone — which is common when eating less — a fiber supplement like psyllium husk (Metamucil) can fill the gap. Psyllium is a soluble fiber that absorbs water and forms a gel-like bulk in the intestines, making stool softer and easier to pass.
Start with a small dose and increase gradually. Always take fiber supplements with a full glass of water — without adequate water, they can actually worsen constipation.
e. Physical activity
Walking and other moderate physical activity help stimulate GI motility. Even 20–30 minutes of daily walking can make a meaningful difference in bowel regularity. Exercise increases blood flow to the intestines and encourages the natural contractions that move waste through the colon.
You do not need intense exercise. A brisk walk after meals is one of the simplest and most effective things you can do.
f. OTC stool softeners if needed
Docusate sodium (Colace) is a gentle over-the-counter stool softener that works by drawing water into the stool, making it easier to pass. It is not a stimulant laxative and is generally safe for regular use. If you are experiencing mild constipation that does not respond to dietary changes alone, a stool softener can be a reasonable next step.
As with any OTC medication, confirm with your PEAK care team that it is appropriate for your situation.
g. Probiotic foods
Probiotic-rich foods can support healthy gut bacteria and improve bowel regularity. Good options include yogurt with live active cultures, kefir, sauerkraut, kimchi, and other fermented foods. While the evidence for probiotics and constipation is still evolving, many patients report improvement when they incorporate fermented foods into their diet.
h. Do not skip meals entirely
Even though GLP-1 medications reduce your appetite significantly, skipping meals entirely can worsen constipation. Eating triggers the gastrocolic reflex — a natural response where eating stimulates movement in the colon. When you skip meals, you lose this natural trigger for bowel activity.
Aim for at least three small meals per day, even if the portions are smaller than what you ate before starting medication. The act of eating itself is part of maintaining regular bowel function.
In our clinical experience, the patients who manage constipation most successfully combine two or three of these strategies together: adequate hydration, increased fiber intake, and daily walking. These three interventions address the root causes directly and are effective for the majority of patients.
When to try OTC laxatives
If dietary changes and stool softeners are not providing enough relief, over-the-counter laxatives may be appropriate. There are two main categories to be aware of:
- Osmotic laxatives (MiraLAX / polyethylene glycol). These work by drawing water into the colon to soften stool. They are generally safe for short-term use and are well-tolerated. Many clinicians consider osmotic laxatives the first-line OTC option after stool softeners.
- Stimulant laxatives (Dulcolax / bisacodyl, Senokot / senna). These stimulate the muscles of the intestine to contract and push waste forward. They are effective for acute constipation but are generally not recommended for daily or long-term use, as the bowel can become dependent on them.
Osmotic laxatives are generally the safer and more appropriate choice for constipation related to GLP-1 medications. They address the core issue — insufficient water in the colon — without creating dependency.
Do not use stimulant laxatives daily without guidance from your provider. If you have severe abdominal pain, vomiting, or suspect a bowel obstruction, do not take any laxative — contact your provider or seek medical attention immediately.
When to contact your provider
Most constipation on GLP-1 medications is mild and manageable with the strategies above. However, there are situations where you should contact your PEAK care team:
- No bowel movement for 3 or more days. While occasional irregularity is normal, going more than three days without a bowel movement warrants a conversation with your provider.
- Severe abdominal pain or bloating. Significant pain, especially if it is worsening or accompanied by distension, may indicate a more serious issue that requires evaluation.
- Blood in your stool. Any rectal bleeding should be reported to your provider promptly, regardless of whether you think the cause is constipation-related (such as hemorrhoids or straining).
- Nausea with constipation. When constipation and nausea occur together, it can indicate that stool is backing up and creating a blockage-like effect. Your provider may need to adjust your treatment plan.
At PEAK, we actively monitor patients for GI side effects during treatment. If constipation is affecting your quality of life, reach out. Early intervention — whether it is a dietary adjustment, a supplement recommendation, or a dose modification — is always more effective than waiting until the problem becomes severe.
Long-term management
The encouraging reality is that for most patients, constipation improves as the body adjusts to GLP-1 medication. The GI tract adapts to the slower motility over time, and patients who implement the dietary and lifestyle changes described above typically find a manageable routine within the first few weeks to months of treatment.
Nutrition adjustments are always the first line of defense. Before reaching for supplements or medications, focus on the fundamentals: adequate fiber, consistent hydration, and regular physical activity. These three factors address the root causes of GLP-1–related constipation directly.
Most patients find that once they establish a routine — a fiber-rich breakfast, a water bottle they carry throughout the day, a daily walk — constipation becomes a manageable and minor part of their treatment experience rather than a significant burden.
Constipation is a common side effect, but it does not have to be a constant one. The right habits make all the difference.
Your PEAK care team is here to help you find the combination of strategies that works for your body. We can adjust your treatment plan, recommend targeted supplements, or modify your dose schedule if constipation is persistent. You do not need to figure this out alone.
Boxed warning — thyroid C-cell tumors: GLP-1-based medications (including semaglutide and tirzepatide) carry an FDA boxed warning for thyroid C-cell tumors observed in rodent studies. These medications are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). Tell your provider immediately if you notice a lump in your neck, difficulty swallowing, or persistent hoarseness.
Medication labeling reminder: Ozempic (semaglutide) and Mounjaro (tirzepatide) are FDA-approved for type 2 diabetes only. For weight management, the FDA-approved options are Wegovy (semaglutide) and Zepbound (tirzepatide).
