Nausea is the one you should expect. It showed up in 25 to 29 percent of people on Zepbound depending on the dose, against 8 percent on placebo, and most of it happened in the weeks right after a dose increase rather than at some fixed point in treatment.
That number, and every other number on this page, comes from Lilly’s prescribing information for Zepbound: two randomised placebo-controlled trials, 2,519 adults, up to 72 weeks. Not from a forum, not from an average of other articles.
Quick answer
56 percent of people on Zepbound get at least one gastrointestinal side effect, at every dose, against 30 percent on placebo. Nausea leads at 25 to 29 percent, then diarrhea at 19 to 23 percent, vomiting at 8 to 13 percent and constipation at 17 down to 11 percent. Most of it clusters around dose escalation and settles once you hold a dose. Between 4.8 and 6.7 percent of people stop because of side effects, depending on dose, against 3.4 percent on placebo.
Zepbound side effects by dose, from the label
Every reaction Lilly reported in at least 2 percent of patients, and more often than placebo. Placebo n=958, 5 mg n=630, 10 mg n=948, 15 mg n=941.
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
| Abdominal pain | 5% | 9% | 9% | 10% |
| Indigestion | 4% | 9% | 9% | 10% |
| Injection site reactions | 2% | 6% | 8% | 8% |
| Fatigue | 3% | 5% | 6% | 7% |
| Allergic-type reactions | 3% | 5% | 5% | 5% |
| Burping | 1% | 4% | 5% | 5% |
| Hair loss | 1% | 5% | 4% | 5% |
| Acid reflux | 2% | 4% | 4% | 5% |
| Gas | 2% | 3% | 3% | 4% |
| Bloating | 2% | 3% | 3% | 4% |
| Dizziness | 2% | 4% | 5% | 4% |
| Low blood pressure | 0% | 1% | 1% | 2% |
The thing that table shows and nobody writes about
Read the constipation row again. 17 percent, then 14, then 11. It gets less common as the dose goes up.
Now read the vomiting row. 8 percent, then 11, then 13. That one goes the other way.
And nausea peaks in the middle, at 10 mg, then eases slightly at 15.
So “side effects get worse at higher doses” is not what happened. The side effect profile changes shape as you climb. The low end of the range is a constipation problem and the top end is a vomiting problem, which matters because they need completely different responses. Fibre and fluid for one. Smaller meals and slowing down the escalation for the other.
This is also why the total gastrointestinal rate is flat at 56 percent across all three doses while the mix underneath it shifts. If you only look at the headline number, nothing changes as you titrate. It does.
When they start, and how long they actually last
Here is the honest version, because this is the question with the most invented answers attached to it.
The label does not give a duration in days. What it says is that the majority of nausea, vomiting and diarrhea events occurred during dose escalation and decreased over time, and separately that most people who stopped because of side effects did so during the first few months of treatment.
So the shape is clear even though the timeline is not: worst after a step-up, easier once you hold. Beyond that, anyone giving you “two to three weeks” is quoting a number that does not exist in the source.
On timing within the week: tirzepatide peaks in your blood around 24 hours after the injection, and its half-life is roughly five days, which means the drug is still fully on board when the next shot is due. That is why the day after the shot is usually the rough one and why nothing fully clears between doses.
Nobody can tell you how long yours will last, which is the whole problem. Regimen logs symptoms against your dose and step-up dates, so after two cycles you have your own answer instead of someone else’s average.
Track your side effects freeWhat about 2.5 mg?
There is no trial answer for 2.5 mg, and it is better to know that than to be handed a made-up figure.
2.5 mg is a starting dose that Lilly explicitly says is not intended for chronic weight management. It exists to let your gut adjust for four weeks. Because it was never a maintenance arm in the trials, it has no column in the adverse reaction table, and neither do 7.5 mg or 12.5 mg, which are the intermediate steps.
What you can take from the label is the pattern: side effects cluster around escalation. Your first four weeks on 2.5 mg and the jump to 5 mg are among the most likely times to feel something, even though 2.5 mg is the smallest dose you will ever take.
Does Zepbound cause nausea, and what actually helps
25 to 29 percent, against 8 percent on placebo. It is the most common side effect at every dose and the most common reason people quit.
What the label supports: it concentrates around dose increases and decreases over time. What it also supports is that if you cannot tolerate a maintenance dose, going back down to a lower maintenance dose is a legitimate move rather than a failure. Lilly says it directly: consider a lower maintenance dosage.
That is worth sitting with, because the instinct on a weight loss drug is to keep climbing. 5 mg is a maintenance dose. So is 10. Staying where you are tolerating it is a real option, not a compromise.
Does Zepbound cause diarrhea?
19 percent at 5 mg, 21 at 10 mg, 23 at 15 mg, against 8 percent on placebo. Steadily up with dose, unlike constipation.
Lilly’s count includes frequent bowel movements as well as diarrhea proper, so some of that 23 percent is “going more often” rather than anything dramatic.
The reason it matters more than it sounds: the label warns about acute kidney injury caused by dehydration from vomiting and diarrhea, and says most reported cases followed exactly that. Acute kidney injury turned up in 0.5 percent of people on Zepbound against 0.2 percent on placebo. Small, but the mechanism is preventable and it is fluid.
Does Zepbound cause constipation?
17 percent at 5 mg, falling to 11 percent at 15 mg, against 5 percent on placebo. Lilly’s count includes hard stools.
If you are at 5 mg wondering whether this improves, the label’s own numbers say it tends to, as you go up. That is the opposite of what most people assume.
Does Zepbound cause fatigue?
5 percent at 5 mg, 6 at 10, 7 at 15, against 3 percent on placebo. Lilly’s category also covers weakness, lethargy and general malaise, so it is broader than tiredness.
Two other rows in the table are worth reading alongside it, because they can feel like fatigue: dizziness at 4 to 5 percent, and low blood pressure at 1 to 2 percent. Low blood pressure showed up in 1.6 percent of people on Zepbound against 0.1 percent on placebo, and in 2.2 percent of those also taking blood pressure medication against 1.2 percent of those not. If you are on an antihypertensive and feeling lightheaded, that is a conversation with your prescriber rather than something to push through.
Does Zepbound cause hair loss?
About 5 percent, and the label is unusually specific about it.
Hair loss was associated with weight reduction rather than attributed to tirzepatide directly. And the sex split is large: 7.1 percent of women against 0.5 percent of men on Zepbound, with the same skew at a lower level on placebo, 1.3 percent against zero.
The detail that says the most: nobody in Lilly’s trials stopped Zepbound because of hair loss, and one person on placebo did.
Are Zepbound side effects worse for women?
For hair loss, clearly yes, at roughly fourteen times the male rate. For the gastrointestinal side effects, the label does not break rates out by sex, so anyone telling you women get more nausea on Zepbound is going beyond the source.
One risk is specific to women and gets missed constantly. Zepbound can reduce the effectiveness of oral hormonal contraceptives, because slowing gastric emptying changes how the pill is absorbed. The label says the effect is largest after the first dose and diminishes over time, and Lilly’s instruction is to switch to a non-oral method or add a barrier method for four weeks after starting and for four weeks after every dose increase. Not just the first one. Every step up the ladder.
What happens if you miss a dose?
Take it within four days, which is 96 hours. Past that, skip it and go back to your normal day. Do not take two doses within three days of each other.
Because the half-life is around five days, one missed week does not reset you. What it does do is scramble your read on how you are responding, and the search volume on this question suggests a lot of people are guessing rather than checking.
A step-up is the only experiment you get to run on yourself, and it only works if you know what the week before looked like. Regimen marks every dose change on your charts and keeps your symptoms, weight and appetite on the same timeline.
Get Regimen freeInjection site reactions, and the antibody thing
6 percent at 5 mg, 8 percent at 10 and 15, against 2 percent on placebo. That is already well above semaglutide, where Novo reports 0.2 percent for Ozempic and 1.4 percent for Wegovy.
Then there is the figure that explains the people who get them constantly. Among those who developed anti-tirzepatide antibodies, injection site reactions ran 11.3 percent, against 1 percent in those who did not. Same for allergic-type reactions: 6.2 percent in antibody-positive people against 3 percent. Most of those were skin reactions, rash and itching.
So injection site trouble on Zepbound is not usually a technique problem. Rotating sites still matters for tissue health, and where to inject and how to rotate covers that, but a persistent pattern is worth raising rather than blaming on yourself.
The serious ones, in proportion
The label carries a boxed warning for thyroid C-cell tumours, based on rodent studies, and Zepbound is contraindicated if you or your family have medullary thyroid carcinoma or MEN 2.
Then the warnings with actual trial numbers behind them:
- Severe gastrointestinal disease. Severe events in 1.7 percent at 5 mg, 2.5 at 10, 3.1 at 15, against 1 percent on placebo. Zepbound has not been studied in severe gastroparesis and is not recommended there.
- Gallbladder. Cholecystitis 0.7 percent against 0.2 percent on placebo. Gallstones 1.1 against 1.0, effectively level. Gallbladder removal 0.2 percent against none. Associated with weight reduction.
- Pancreatitis. 0.2 percent on Zepbound and 0.2 percent on placebo, adjudicated. Not elevated in these trials. The warning stands because it has been seen with GLP-1 drugs and with tirzepatide elsewhere, and because Zepbound has never been studied in people with a history of it.
- Low blood sugar. In people with type 2 diabetes and BMI 27 or over, 4.2 percent against 1.3 percent on placebo. On a sulfonylurea as well, 10.3 percent, against 2.1 percent without one. That is the interaction to raise with your prescriber before you start.
- Suicidal behaviour and ideation. Reported in trials of other chronic weight management drugs rather than in Zepbound’s own. The label still says to monitor for new or worsening depression or unusual mood changes, to stop if suicidal thoughts appear, and to avoid Zepbound entirely with a history of suicide attempts or active suicidal ideation.
Two lab values move on Zepbound without necessarily meaning anything: pancreatic amylase up 20 to 25 percent and lipase up 28 to 35 percent on average, against 2.1 and 5.8 percent on placebo. The label says the significance is unknown in the absence of other signs of pancreatitis, which is worth knowing before a routine panel alarms you.
Reported after approval, without reliable frequencies: anaphylaxis, angioedema, and ileus.
When to call your prescriber
- Persistent severe abdominal pain, especially radiating to your back, with or without vomiting. That is the pancreatitis presentation.
- Vomiting or diarrhea you cannot keep ahead of with fluids, because that is the route to kidney injury.
- Any allergic reaction: swelling, trouble breathing, a spreading rash.
- Lightheadedness that keeps happening, particularly on blood pressure medication.
- New or worsening low mood, or any thoughts of self-harm.
- Vision changes, if you have diabetic retinopathy.
The unglamorous truth about these appointments is that they go better with data. “Nausea, days one and two, every week since the 10 mg step on August 4, worst at 7 out of 10” gets you somewhere. “I’ve been feeling rough” gets you sympathy.
Regimen turns what you logged into the summary you bring to the appointment: symptoms by day, plotted against your doses and step-ups, with weight and appetite alongside. Free for one medication, no time limit and no card.
Start tracking freeZepbound versus Mounjaro versus semaglutide
Zepbound and Mounjaro are the same molecule, tirzepatide, approved for different things. The trials behind them enrolled different populations, obesity for one and type 2 diabetes for the other, so the percentages are not interchangeable and we would rather say so than build you a comparison table out of mismatched trials.
The one cross-drug number that is clean is injection site reactions, because both manufacturers report it the same way: Zepbound 6 to 8 percent, Ozempic 0.2 percent, Wegovy 1.4 percent. That gap is real and it surprises people who switch. For the semaglutide side of it, Ozempic side effects by dose gives Novo’s label the same treatment.
How common is it to quit?
4.8 percent at 5 mg, 6.3 at 10, 6.7 at 15, against 3.4 percent on placebo. Gastrointestinal side effects specifically: 1.9, 3.3 and 4.3 percent by dose, against 0.5 percent.
Turned around: about nineteen in twenty people who reach a maintenance dose stay on it. Most of the leaving happens in the first few months, which lines up with everything else on this page. The early weeks are the hard part.
Sources
All Zepbound percentages, the discontinuation rates, the antibody figures, the hair loss sex split, the laboratory changes, the contraception guidance, the dosing schedule and every warning above come from Eli Lilly’s prescribing information for Zepbound (tirzepatide) injection, FDA application 217806, label revised 28 August 2026, sections 2.2, 2.3, 5.1 to 5.9, 6.1, 6.2, 7.1, 7.2 and 8.3.
The Ozempic and Wegovy injection site reaction rates come from Novo Nordisk’s prescribing information for those products. Tirzepatide’s time to peak of about 24 hours comes from the Mounjaro label, NDA 215866. The missed dose window is from Lilly’s Medication Guide.
Sources verified 8 September 2026.
This article is for tracking and education. It is not medical advice, and dosing questions belong with your prescriber.
Frequently asked questions
What are the most common Zepbound side effects?
Nausea, diarrhea, vomiting and constipation, in that order. From Lilly's prescribing information, nausea affected 25 percent of people on 5 mg, 29 percent on 10 mg and 28 percent on 15 mg, against 8 percent on placebo. Diarrhea ran 19 to 23 percent, vomiting 8 to 13 percent, constipation 17 down to 11 percent. Any gastrointestinal side effect at all: 56 percent at every dose, against 30 percent on placebo.
How long do Zepbound side effects last?
The label does not give a number of days, and anyone quoting you one is making it up. What it does say is that the majority of nausea, vomiting and diarrhea events happened during dose escalation and decreased over time, and that most people who quit because of side effects quit in the first few months. So the pattern is: worst after a step-up, easier once you settle. How long your own version lasts is something only your own log can answer.
When do Zepbound side effects start?
Usually within the first day or two after an injection, and most intensely in the weeks after a dose increase rather than at any fixed point in treatment. Tirzepatide takes about 24 hours to peak in your blood and has a half-life of around five days, so the drug is still fully present when the next shot is due. That is why the days right after the shot tend to be the rough ones.
What are the side effects of Zepbound 2.5 mg?
There is no trial answer, and that is worth knowing rather than guessing at. The 2.5 mg dose is a starting dose that is explicitly not intended for chronic weight management, so it was never a randomised maintenance arm and has no column in the label's adverse reaction table. What the label does tell you is that side effects cluster around dose escalation, so the first four weeks at 2.5 mg and the jump to 5 mg are exactly when to expect them.
Does Zepbound cause constipation, and does it get worse at higher doses?
It causes it in a meaningful share of people, and it gets better at higher doses, not worse. Constipation ran 17 percent at 5 mg, 14 percent at 10 mg and 11 percent at 15 mg, against 5 percent on placebo. It is the only common side effect in the table that falls as the dose rises. Vomiting does the opposite, going from 8 percent to 13 percent.
How many people stop taking Zepbound because of side effects?
4.8 percent at 5 mg, 6.3 percent at 10 mg and 6.7 percent at 15 mg permanently stopped because of side effects, against 3.4 percent on placebo. Gastrointestinal side effects specifically accounted for 1.9, 3.3 and 4.3 percent by dose against 0.5 percent on placebo. So roughly nineteen in twenty people who start on a maintenance dose stay on it.
Which Zepbound side effects are serious?
The label carries a boxed warning for thyroid C-cell tumours and separate warnings for severe gastrointestinal disease, acute kidney injury, gallbladder disease, pancreatitis, hypersensitivity reactions, low blood sugar, diabetic retinopathy complications, and suicidal behaviour and ideation. In practice the numbers are small: acute kidney injury 0.5 percent against 0.2 percent on placebo, cholecystitis 0.7 percent against 0.2 percent. Persistent severe abdominal pain that may radiate to your back is the one to treat as urgent, since that is how pancreatitis presents.
Does Zepbound affect birth control?
It can, and this one gets missed. Zepbound may reduce the effectiveness of oral hormonal contraceptives because it slows how fast your stomach empties, and the label says the effect is largest after the first dose. Lilly's instruction is to switch to a non-oral method or add a barrier method for four weeks after starting, and for four weeks after every single dose increase. Not just the first one.
Does Zepbound cause pancreatitis?
In Zepbound's own trials it did not happen more often than on placebo: 0.2 percent of people on Zepbound had adjudicated acute pancreatitis, and 0.2 percent on placebo did. The label still warns about it, because pancreatitis has been observed with GLP-1 drugs and tirzepatide generally, and because Zepbound has never been studied in people with a history of pancreatitis. Zepbound also raises pancreatic amylase by 20 to 25 percent and lipase by 28 to 35 percent on average, which the label says has unknown significance without other symptoms.
Can Zepbound affect your mental health?
The label tells you to watch for it and is honest about where the concern comes from: suicidal behaviour and ideation have been reported in trials of other chronic weight management drugs, not in Zepbound's own trials. Lilly's instruction is to monitor for new or worsening depression or unusual changes in mood, to stop Zepbound if suicidal thoughts appear, and to avoid it entirely if you have a history of suicide attempts or active suicidal ideation.
How do Zepbound side effects compare to Ozempic and Wegovy?
On injection site reactions the gap is large and well documented: Zepbound reports 6 to 8 percent depending on dose against 2 percent on placebo, while Novo reports 0.2 percent for Ozempic and 1.4 percent for Wegovy. So if you switched from semaglutide and started getting lumps and redness, that is the drug rather than your technique. For the gastrointestinal side effects the two drugs were tested in different trials on different populations, so the percentages are not directly comparable and we would rather say that than pretend otherwise.
