Drug facts
Tirzepatide and constipation
Reviewed August 2026
Quick answer
It is common and it is in the label. In the obesity trials 17% of participants reported constipation at 5 mg, 14% at 10 mg and 11% at 15 mg, against 5% on placebo. It is the one common reaction that becomes less frequent as the dose rises — and that is an artefact of who reaches the higher doses, not evidence that more drug is gentler.
How common it was1
Constipation is one of twelve reactions the approved label reports in 5% or more of trial participants. Its rates, pooled from the two pivotal obesity trials and shown by dose with the placebo column beside them:
| Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|
| 5% | 17% | 14% | 11% |
The placebo column is the part worth reading. One person in twenty reported constipation without the drug at all, so the number that describes tirzepatide is the difference — roughly twelve points at 5 mg, falling to six at 15 mg — not the headline percentage.
For scale, it sits below nausea (25–29%) and diarrhea (19–23%) and above vomiting (8–13%). The full table of reported reactions →
It gets less common at higher doses1
17% → 14% → 11% runs the opposite way to almost everything else in the table, and it is tempting to read it as the drug settling down. That is not what the numbers say.
Participants only reach 10 mg and 15 mg by tolerating 5 mg first. The higher-dose columns therefore describe a group already filtered for tolerating the drug — anyone whose constipation was bad enough to stop is not in them. The pattern is real and it is in the label, but it is a fact about who is left, not a promise that titrating up will help. Nausea does the same thing for the same reason, peaking at 10 mg rather than 15 mg.
Why the drug does this2
The label states, in the section on interactions with oral medicines, that tirzepatide delays gastric emptying — food leaves the stomach more slowly. That is part of how the drug produces fullness, and slower transit through the gut is the same mechanism seen from the other end.
The label raises delayed gastric emptying as a reason it can affect oral medicines, including oral contraceptives, rather than as an explanation for constipation. What the label says about interactions →
When it is not just constipation1
The same label describes, separately from the common-reaction table, risks that include severe gastrointestinal disease, acute pancreatitis and acute gallbladder disease. Those are not rated by frequency here, because a percentage is the wrong tool for them: any of them is a reason to contact a prescriber rather than to consult a table.
This page reports how often constipation was recorded in trials. It cannot tell you whether what you are experiencing is that.
What none of this covers
On the label — Mounjaro / Zepbound
These rates come from controlled trials of the approved product, at known doses, with an approved manufacturing process behind every injection.
In a compounded vial
No equivalent trial data exists for a compounded preparation. The molecule should behave like the molecule, but concentration and excipients differ between compounders, and nothing about those is covered by these numbers. What is actually different →
Nothing here is medical advice, and this page deliberately suggests no remedy. Whether a side effect needs managing, and how, is a question for the prescriber who wrote the prescription. See the medical disclaimer.