Yes, for a minority of people. Fatigue is one of the side effects Zepbound's label lists as common, reported by 5% to 7% of people across doses against 3% on placebo [1]. That's about 1 in 14 on the highest dose, a much smaller share than the roughly 1 in 4 who reported nausea. The more useful question is what's behind it, because the label points to a few causes your prescriber can check. For the drug itself, see the Zepbound guide.
Fatigue rose with the dose, from 5% to 7%
The figures come from two 72-week trials pooled together, about 3,500 adults in all [1]. The label's footnote matters: its "fatigue" row includes asthenia (weakness), fatigue, lethargy and malaise. So a person who felt weak or generally unwell counts here too, not only someone who felt sleepy.
| Effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Fatigue (includes weakness, lethargy, malaise) | 3 | 5 | 6 | 7 |
| Dizziness | 2 | 4 | 5 | 4 |
| Low blood pressure (includes blood pressure decreased) | 0 | 1 | 1 | 2 |
| Nausea, for comparison | 8 | 25 | 29 | 28 |
Zepbound prescribing information, Table 1 (Studies 1 and 2 pooled) [1].
The gap over placebo is small: 2 to 4 extra people in every 100. Fatigue on Wegovy, the semaglutide brand for weight, ran higher in its own trials, 11% against 5% on placebo [3]. The trials were different, so treat that as a rough contrast rather than a head-to-head result. Details are in does Wegovy make you tired?
"Sleepy" and headaches aren't trial side effects on the label
Sleepiness isn't a separate entry in Zepbound's side-effect tables. If you feel drowsy, the closest labeled match is the fatigue row above. Headache isn't in those tables either. The word appears in the Medication Guide only as one possible sign of low blood sugar, alongside drowsiness, dizziness, sweating and shakiness [1].
That doesn't mean nobody on Zepbound gets headaches. It means the trials didn't find them often enough, over placebo, for the label to list them. Dizziness is listed, at 4% to 5% against 2% on placebo. The wider list of side effects is in Zepbound side effects and, across both tirzepatide brands, tirzepatide side effects.
Stomach side effects can drain fluids, and that can leave you wiped out
Digestive side effects were the big ones: 56% of people on any Zepbound dose had one, against 30% on placebo. The label says most nausea, vomiting and diarrhea "occurred during dose escalation and decreased over time" [1]. Vomiting and diarrhea can leave you short of fluid, and the label ties that to two problems that feel a lot like exhaustion.
- Low blood pressure. It happened in 1.6% of people on Zepbound against 0.1% on placebo, more often in people taking blood pressure medicines (2.2%), and "in association with gastrointestinal adverse events and dehydration."
- Kidney strain. The label warns that fluid loss from nausea, vomiting or diarrhea can lead to acute kidney injury, especially while the dose is starting or rising.
The Medication Guide's own advice is short: it's "important for you to drink fluids to help reduce your chance of dehydration," and to tell your healthcare provider "right away" about nausea, vomiting or diarrhea that doesn't go away [1]. Constipation is the other common stomach effect; see does Zepbound cause constipation?
Low blood sugar can feel like drowsiness, mainly with diabetes
Zepbound on its own rarely drops blood sugar too low. In the trial of people without diabetes, a glucose reading below 54 mg/dL showed up in 0.3% of people on Zepbound. In the trial of people with type 2 diabetes, it was 4.2% against 1.3% on placebo [1]. The label says the risk is higher with insulin or a sulfonylurea, and that those medicines may need a lower dose.
The Medication Guide's list of low-blood-sugar signs includes "confusion or drowsiness," headache, weakness, dizziness, sweating, shakiness and hunger [1]. If you have diabetes and tiredness comes with those, treat it as a possible low and follow the plan your care team gave you.
Mounjaro reported fatigue too, and compounded tirzepatide wasn't tested
Mounjaro is the same molecule, labeled for type 2 diabetes. Fatigue isn't in its main side-effect table. But in its heart-outcomes trial of 6,647 adults with type 2 diabetes and heart disease, which compared it with another GLP-1 drug, the label lists fatigue at 10% among the reactions that stood out [2]. That trial followed people with diabetes and established heart disease for a median of about four years, so its rates aren't comparable with the weight trials.
Compounded tirzepatide isn't FDA-approved, the FDA doesn't review it for safety or effectiveness, and it doesn't check its quality before it ships. Its side-effect rates have never been measured in a trial; the figures above belong to the brand products. See is compounded tirzepatide safe?
When tiredness needs a call to your prescriber
- Tiredness with vomiting or diarrhea that won't stop: possible dehydration, which the label links to kidney problems.
- Dizziness or fainting when you stand, especially if you take blood pressure medicine.
- Drowsiness with shakiness, sweating or confusion if you take insulin or a sulfonylurea: possible low blood sugar.
- Severe pain in your stomach area that won't go away, with or without nausea or vomiting, sometimes reaching your back. The Medication Guide lists it as a possible sign of pancreatitis and says to call right away.
These come from the label's warnings and Medication Guide [1]. For plain, mild tiredness, the label offers no timeline, so mention it at your next check-in, and sooner if it's getting worse. Any change to your dose is your prescriber's decision; the label's dose range is explained in Zepbound dosage.
Weighing programs on price? The brand Wegovy and Zepbound self-pay programs lineup sets 21 of them side by side, each with its true monthly cost.