GLP-1 receptor agonist medications (GLP-1 RAs) — like semaglutide (e.g., Ozempic, Wegovy) and tirzepatide (e.g., Mounjaro, Zepbound) — are now widely used for weight loss and diabetes management. Their potent results have led to a steep uptick in use, with many people seeing dramatic improvements in their health. Unfortunately, like most medications, they come with potential side effects that range from unpleasant to unbearable.
Gastrointestinal (GI) side effects are among the most common, as evidenced by the fact that nearly all clinical trials of GLP-1 RAs document these problems. The most frequent GI side effects include nausea, vomiting, diarrhea, and constipation. Because these medications slow stomach and intestinal movement, nausea and constipation are an unsurprising result. That same slowing is responsible for the benefits (lower blood glucose levels and decreased appetite) and the drawbacks.
What’s Happening in Your Gut
Let’s focus on the constipation and diarrhea, and their downstream effects on the anus, for people taking GLP-1 RAs.
Constipation makes logical sense for several reasons: people are eating less, which often means reduced fiber and water intake; food moves more slowly through the GI tract; and there is some evidence that injectable GLP-1 RAs can reduce colonic contractions.
Diarrhea, on the other hand, is a more complex issue. GLP-1 RAs can activate parts of the brain that regulate gut function, resulting in increased intestinal secretions and heightened intestinal nervous system activity. There is also a well-supported belief — backed by major medical associations — that prolonged constipation can trigger what’s known as reactive diarrhea.
In either case, symptoms tend to be worst when first starting these medications or increasing the dose. Over time, many people see improvement, but GI side effects remain one of the top reasons people discontinue GLP-1 RAs. Being prepared matters.
Managing Constipation and Diarrhea
The standard advice holds here: increase water and fiber intake and eat a diet rich in whole foods. But for many people, that alone isn’t enough to combat GLP-1 RA-induced GI side effects. A word of caution: adding too much fiber too quickly can worsen bloating — the last thing anyone needs on top of everything else.
For constipation: Talk to your physician about temporarily using a laxative — not a stool softener. Stool softeners (like Colace) have zero clinical evidence supporting their effectiveness in any situation, including GLP-1 RA-induced constipation. There are several types of laxatives, and you may need to try more than one (not simultaneously) to find what works for you. Most are intended for short-term use, so if you need long-term treatment, your options may be more limited. For a deeper dive into laxative types, check out our article “How to Prevent Constipation After Surgery.”
For diarrhea: Avoiding high-fat meals may help. Over-the-counter anti-diarrheal medications are an option when symptoms are significant. You can also discuss with your physician the possibility of increasing your dose more slowly, giving your body more time to adjust.
Patience matters, too. In many cases, temporary management strategies combined with time will allow these side effects to ease or resolve entirely.
Protecting Your Booty in the Meantime
Your anus is a sensitive area. Both constipation and diarrhea can irritate the skin, and how you clean yourself makes an enormous difference.
Cleaning hierarchy:
- Bidet (gold standard) — Water irrigation eliminates the friction and chemical exposure of wiping entirely.
- Pat dry — If you use toilet paper after a bidet, pat — do not rub. A blow dryer on the lowest heat setting is also a good option.
- Dry toilet paper only — If a bidet isn’t available, use unscented, plain toilet paper and be as gentle as possible. In this case, apply a skin barrier ointment to the anal area before your bowel movement. This protects the skin and makes cleaning easier.
A few other rules:
- No flushable wipes — ever. Despite the name, they are not kind to sensitive skin.
- Limit toilet time to 2–3 minutes. Use a timer if you need to.
- Minimize thongs and daily pantiliners. Choose gentle, breathable underwear instead.
- Put a stool under your feet when on the toilet and lean forward. This mimics a squatting position, which is a more natural and mechanically easier posture for a bowel movement.
- Don’t push through a hard stool. Even one firm, painful bowel movement — or just a firm first portion — can cause an anal fissure, which is a small cut or tear in the anal tissue. If the stool lowest in the rectum is already hard, an oral laxative can’t reach it. In that situation, consider using an enema rather than straining through it. It’s a much kinder option for your anus. The liquid from the enema can break up the hard stool and help it pass more easily.
Apply a barrier ointment to the anal skin before and after bowel movements. Look for a plant-based, fragrance-free, paraben-free formula with no synthetic preservatives. Clinical evidence supports structured skin care and barrier ointments for maintaining skin integrity and protecting delicate anal tissue from friction and moisture loss — especially when bowel habits are irregular or frequent. This will help ease discomfort if having either diarrhea or constipation.
Don’t Skip Your Colonoscopy
If something seems off, don’t assume your bowel movement changes are due to the medications. Nothing in this article is more important than this: a colonoscopy is the only way to find polyps before they become cancer. Polyps removed during a colonoscopy cannot turn into cancer. This is how colonoscopies save lives — not theoretically, but in reality.
Colorectal cancer rates are rising, including among younger adults. Even painless, seemingly minor anal or rectal bleeding should never be dismissed without evaluation. If you’re due for a colonoscopy or haven’t had one, bring it up at your next appointment — even if your physician doesn’t.
When to Seek Medical Evaluation
Don’t wait. See a physician if you experience:
- Any painless anal or rectal bleeding (do not assume it’s hemorrhoids)
- Pain that persists beyond a few days
- Intense or severe anal pain (help is available — don’t suffer unnecessarily)
- Fever associated with anal pain or swelling
- Any mass or growth that doesn’t belong
- Any persistent change in bowel habits lasting more than a few days
- Persistent drainage, itching, or the sensation of something protruding
- Any concern that something isn’t right — trust yourself