Yes, and far more often at the weight-loss dose than at the diabetes doses. In the diabetes trials behind the Ozempic label, constipation affected 5.0 percent of people on 0.5 mg and 3.1 percent on 1 mg, against 1.5 percent on placebo [1]. At 2.4 mg, the dose sold as Wegovy, it reached 24.2 percent of 2,117 adults against 11.1 percent of 1,262 on placebo across three 68-week trials, and nearly all of those stomach side effects were mild to moderate [2].
It tends to arrive in the first months, in the weeks when the pen is being stepped up and a smaller plate at dinner has become the new normal, and the trials place it there too. The numbers below come from the placebo-controlled trials, because the placebo arm is the only way to tell how much of that constipation belongs to the drug. It turns out that about one person in nine on placebo reported it too.
How often Ozempic causes constipation, dose by dose
The Ozempic label draws its table from two placebo-controlled trials in type 2 diabetes, in which 521 people took the drug for a mean of 32.9 weeks [1]. Constipation made the table at 5.0 percent on 0.5 mg and 3.1 percent on 1 mg, well behind nausea at 15.8 to 20.3 percent. At those diabetes doses it is one of the quieter side effects, and nausea is the one that sets the tone, as how long nausea lasts on a GLP-1 describes.
The weight-loss dose is a different picture. Pooling the STEP 1 to 3 trials, constipation ran at 24.2 percent on semaglutide 2.4 mg against 11.1 percent on placebo, the fourth most common stomach complaint after nausea, diarrhea and vomiting [2]. The Wegovy label prints the same trials as 24 percent against 11 percent [3]. Put plainly, about one extra person in eight became constipated because of the drug rather than the diet, the season or the travel that would have done it anyway.
How bad it gets, and how many stop
Most of it was mild. Across the stomach side effects in those trials, 99.5 percent of events were non-serious and 98.1 percent were mild to moderate, and 4.3 percent of people on semaglutide stopped the drug permanently because of them [2]. The same analysis found that weight loss was about the same whether or not someone had stomach side effects. A constipated month is not a sign the drug is working harder, a point taken further in why GLP-1 drugs cause nausea.
The labels also carry a rarer tail that the trial tables are too small to count. Since approval, reports have included severe constipation with fecal impaction, ileus and intestinal obstruction, listed as post-marketing reactions whose frequency cannot be estimated [1]. Those belong in a different conversation from the usual slow week, and the closest cousin, a stomach that stops emptying, is covered in whether GLP-1 drugs cause gastroparesis.
Zepbound and Mounjaro: tirzepatide’s numbers
Tirzepatide causes constipation too. The Zepbound label, from two obesity trials, lists it at 17 percent on 5 mg, 14 percent on 10 mg and 11 percent on 15 mg, against 5 percent on placebo, a row that falls as the dose rises [4]. The Mounjaro label, from diabetes trials, lists it at 6 to 7 percent against 1 percent, and at 13 percent in a cardiovascular outcomes trial of 6,647 adults [5].
The FDA database points in the same direction from the other side. In 123,145 reports for tirzepatide, constipation was reported with lower odds than for semaglutide, along with vomiting and decreased appetite [6]. That is a comparison of reports, not users, and no trial has randomized people between the two drugs with constipation as the outcome; the head-to-head trial that exists measured weight, as tirzepatide against semaglutide explains.
When it tends to ease
The trials place stomach side effects in the escalation weeks. The STEP analysis found they occurred most frequently during or shortly after dose escalation and were transient [2], and the tirzepatide obesity trial reported the same pattern across its 20-week escalation [7]. A review of 26 randomized trials in 15,491 people without diabetes found stomach side effects in 47 to 84 percent of people on a GLP-1 against 13 to 63 percent on placebo. Constipation was among the most common [8].
What is still missing is a timetable. None of these trials published constipation by week, so there is no measured answer to whether it settles a month after the last dose step or lingers through maintenance. People who already had bowel trouble before starting are asking a different question again, one with its own evidence in whether GLP-1 drugs help IBS. How side effects weigh against weight loss across every obesity drug is set out in the 262-trial ranking of weight lost against dropout.