Constipation on Mounjaro and Zepbound: Why It Happens and What Helps

Constipation is one of the most common digestive changes people notice on tirzepatide, the medication in Mounjaro and Zepbound. It is usually manageable with a few adjustments to fiber, fluids, and daily routine. Here is what the trial data shows, why it happens, and what tends to help.

How common is constipation on tirzepatide?

• Zepbound: 11% to 17% of patients reported constipation across doses in the weight management trials, compared with 5% on placebo, according to the Zepbound prescribing information.
• Mounjaro: 6% to 7% of patients reported constipation in the placebo-controlled SURPASS trials, compared with 1% on placebo.

In other words, most people on tirzepatide do not get constipated, but it is common enough that it is worth planning for, especially early in treatment.

Why it happens

A few things tend to stack up at once:

• Slower digestion. Tirzepatide slows how quickly food moves through your digestive system. The longer stool stays in the colon, the more water is absorbed and the harder it becomes.
• Less food, less fiber. When your appetite drops, total fiber intake usually drops with it.
• Less fluid. Food provides a meaningful share of daily water, and many people also drink less when they feel full. Fiber needs water to work.
• Less movement. Fatigue in the first weeks can mean less walking, and physical activity helps keep the bowels moving.

What helps

Add fiber slowly

Fiber helps, but adding a lot at once can make bloating and gas worse, which is a real concern when your stomach is already slower than usual. GoodRx recommends increasing fiber gradually. A practical approach is to add a small amount every few days rather than doubling your intake overnight.

Favor gentle, soluble fiber

Soluble fiber absorbs water and forms a soft gel, which helps keep stool easier to pass. Oats, beans, lentils, apples, pears, berries, chia, and carrots are good food sources. If you use a supplement, gentler options like partially hydrolyzed guar gum (PHGG) tend to cause less bloating than some others. Our guide to the best fiber supplement for GLP-1 users compares the main types, and our PHGG guide explains why it is often recommended.

Drink more than you think you need

Without enough water, extra fiber can sit in the gut and make things worse. Sip steadily throughout the day rather than trying to catch up all at once. If you are drinking a lot of plain water and still feel drained, you may also be low on electrolytes. See how to stay hydrated on GLP-1 medications.

Move every day

A daily walk, even 15 to 20 minutes after a meal, can help stimulate digestion.

Keep a routine

Eating at roughly the same times each day and giving yourself unhurried time in the bathroom, often after breakfast, helps your body settle into a rhythm.

Ask about magnesium or a laxative if needed

Some forms of magnesium, such as magnesium citrate, have a mild laxative effect. If food and fluids are not enough, your provider or pharmacist can recommend an appropriate over-the-counter option. Check with them before starting anything new, especially if you have kidney problems.

When to call your doctor

Contact your healthcare provider if you have not had a bowel movement in several days, if you have severe abdominal pain or swelling, if you are vomiting, or if you notice blood in your stool.

Where Alula fits

Alula is a daily drink mix built for people on GLP-1 medications. Each stick includes 2 g of partially hydrolyzed guar gum fiber and a Bacillus coagulans probiotic (about 2 billion CFU) to support digestive comfort and regularity, plus electrolytes (350 mg sodium, 220 mg potassium, and 130 mg magnesium) to support hydration.* It also includes 250 mg of ginger root extract, 1,500 mg of calcium HMB, 2 g of collagen peptides, and a full panel of vitamins and minerals to help fill the nutritional gaps that come with eating less. It works alongside fiber-rich food, water, and movement, not instead of them.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Alula is a dietary supplement, not a GLP-1 medication. Talk with your healthcare provider before starting any new supplement.

Frequently asked questions

Does Mounjaro cause constipation?

It can. In the SURPASS trials, 6% to 7% of people taking Mounjaro reported constipation, compared with 1% on placebo. Rates were higher in the Zepbound weight management trials.

Is constipation worse on Zepbound or Mounjaro?

Both contain tirzepatide. Constipation was reported more often in the Zepbound weight management trials than in the Mounjaro diabetes trials, but the trials studied different groups of people at different doses, so a direct comparison is difficult.

Does constipation on tirzepatide go away?

For many people it improves as eating and drinking habits settle. It can return around dose increases, so it helps to keep fiber, fluids, and movement consistent.

What is the best fiber for constipation on a GLP-1?

Soluble fiber from food is a good starting point. If you use a supplement, gentle options like PHGG or psyllium, added slowly with plenty of water, are commonly recommended.