How to Manage Constipation on GLP-1 Medications

Constipation is one of the most common side effects of GLP-1 medications, alongside nausea and diarrhea, and stomach side effects are reported most often while the dose is being increased. The good news: a few simple eating and hydration habits make a big difference.

Why GLP-1 medications cause constipation

GLP-1 medications slow digestion, starting with how quickly your stomach empties. In the main trials summarised by the 2025 joint advisory on nutrition with these medicines, constipation affected 24% of people on semaglutide 2.4 mg (Wegovy) and 17% on tirzepatide 15 mg (Zepbound), against 11% and 5% on placebo. A smaller appetite often means you're also eating less fibre and drinking less, which compounds the problem. The advisory says constipation should be managed proactively, so start these habits early rather than waiting for it.

Get enough fibre, the right way

• Aim for the standard targets: in the US, 25 g a day for women and 38 g for men up to age 50, and 21 g and 30 g over 50; in the UK, 30 g for all adults. The fiber calculator works out your own number, and fiber on a GLP-1 covers the best sources.
• Mix soluble fibre (oats, beans, lentils, apples, psyllium) with insoluble fibre (whole grains, vegetables, skins).
• Increase fibre gradually and with plenty of fluid. Adding fibre without water can actually make constipation worse.
• If more fibre makes it worse, ease off. The advisory notes that foods high in fibre, protein or fat slow the stomach further and can worsen constipation for some people, sometimes needing a temporary cut-back. Talk to your prescriber or a dietitian if that's you.
• Because your appetite is small, lead with nutrient- and fibre-dense foods so every bite counts. See our high-protein foods guide and the recipes for fibre-rich, high-protein options.

Drink more than you think

Eating less usually means drinking less too, and the 2025 joint advisory says adequate fluids and fibre from foods should be encouraged for constipation. Tea and coffee count; see coffee and tea on a GLP-1. Sip water steadily through the day rather than relying on feeling thirsty. The water calculator gives you a daily target.

Keep moving

Gentle, regular movement, even a daily walk, helps keep your digestion moving. It's a simple, no-downside habit that supports everything above.

Supplements: check first

Some people use a psyllium fibre supplement or magnesium to stay regular. These can help, but they should fit your overall plan. Check with your doctor or pharmacist first, especially alongside other medications. We don't provide dosing advice.

When to see a doctor

Contact your healthcare provider if constipation is severe, lasts more than a few days, or comes with significant pain, bloating, or vomiting. They can look at what's causing it and what will help.

General nutrition information only. For persistent or severe symptoms, or before starting any supplement, talk to your doctor or dietitian.