Constipation

Medication Constipation: Why It Lingers and How to Plan for It

Written by golp Editorial Team Sources listed at the end of this post. Updated October 2026 1 min read

Short answer

Constipation is one of the most common side effects of weight management medication, and it tends to outlast the others. In the STEP trials, it lasted a median of 47 days, against 8 days for nausea. A sensible approach is to plan for it early: steady fluids, fiber added gradually, daily movement, a regular bathroom routine, and a backup option agreed with your prescriber.

Why it matters

Most people starting weight management medication are warned about nausea. Fewer hear that constipation is the side effect most likely to stick around, so it often gets dealt with late, once it's already uncomfortable.
Eating less adds to it. A 2025 joint advisory from four US obesity and nutrition societies reports that these medications cut energy intake by 16 to 39% compared with placebo. Less food usually means less fiber and often less fluid, which leaves less bulk to keep things moving.

What the evidence says

A pooled analysis of the STEP 1 to 3 trials of a 2.4 mg weekly injection, covering 3,379 adults over 68 weeks, found constipation in 24.2% of people on the medication vs 11.1% on placebo. The median episode lasted 47 days, compared with 8 days for nausea, and 98.1% of gut side effects were mild to moderate.
The prescribing information for a dual-action weekly injection reports constipation in 11 to 17% of people, depending on dose, vs 5% on placebo. Its type 2 diabetes counterpart is the same medicine. The label also notes it delays stomach emptying, most noticeably after the first dose.
The 2025 joint advisory encourages fluids and fiber from food, notes that additional strategies are often required, and lists options to discuss with a clinician, including fiber supplements, magnesium citrate, polyethylene glycol 3350 and stool softeners.

The golp take

Constipation on weight management medication is worth planning for from week one, not waiting out. The trial data says it lasts far longer than most people are told, and the advisory is clear that food and fluids alone often aren't enough. The most useful thing you can do early is talk to your prescriber, so a backup plan is agreed before you need it. If you're struggling to get enough fiber in, we made golp for exactly this. Two gummies, 4g of fiber, nothing to mix.

What to do

  • Set up your routine from week one, before constipation starts
  • Drink steadily through the day, especially when you add fiber
  • Add fiber-rich foods gradually, as the NIH suggests: oats, berries, pears, beans and lentils
  • Move every day, even a short walk counts, and try to go at the same time each day
  • Get medical help right away for constant stomach pain, vomiting, being unable to pass gas, blood in your stool, fever or lower back pain
  • Ask your prescriber for a backup option before you need one, and never change your dose without them

Related questions

Sources

  1. Wharton S, Calanna S, Davies M, et al. Gastrointestinal tolerability in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss. Diabetes Obes Metab. 2022.
  2. Eli Lilly and Company, weekly injection prescribing information, uspl.lilly.com
  3. Mozaffarian D, Agarwal M, Aggarwal M, et al. Joint Advisory from ACLM, ASN, OMA, and TOS. Am J Clin Nutr. 2025;122(2):344-367.
  4. National Institute of Diabetes and Digestive and Kidney Diseases, Treatment for Constipation, niddk.nih.gov
  5. National Institute of Diabetes and Digestive and Kidney Diseases, Eating, Diet, & Nutrition for Constipation, niddk.nih.gov
  6. National Institute of Diabetes and Digestive and Kidney Diseases, Symptoms and Causes of Constipation, niddk.nih.gov

FAQs

Does weight management medication cause constipation?

Yes. It's a known side effect of the most common weekly injections. In the STEP weight-loss trials, 24.2% of people reported constipation vs 11.1% on placebo.

Do dual-action weekly injections cause constipation?

They can. In the weight-loss trials for one dual-action weekly injection, 11 to 17% of people reported constipation depending on dose, vs 5% on placebo. Its type 2 diabetes version contains the same medicine.

How long does medication-related constipation last?

In the STEP trials, the median episode lasted 47 days, much longer than nausea at 8 days.

When is medication-related constipation an emergency?

Get medical help right away if it comes with constant stomach pain, vomiting, being unable to pass gas, blood in your stool, fever or lower back pain.

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