Everything below comes from the FDA approved prescribing information for tirzepatide. Not from a survey, not from a forum, not from our own patients. Where a number appears, it is the figure the label reports, and the label is linked at the bottom so you can check it.
This page is general information, not medical advice. It does not replace the prescribing information you receive with your medication or a conversation with the clinician who prescribed it. If you are experiencing symptoms, contact your prescriber.
One thing to be clear about first
The safety data below was generated in trials of FDA approved tirzepatide products. Compounded tirzepatide is a different thing.
Compounded medications are prepared by a licensed compounding pharmacy for an individual patient. They are not reviewed or approved by the FDA for safety or effectiveness, and no compounded version has been through the trials that produced these numbers. It is reasonable to expect the same active ingredient to behave similarly. It is not the same as having been measured.
Any site that hands you these percentages while selling you a compounded product, without saying that, is being less than straight with you. If you are considering a compounded version, read our page on compounded tirzepatide as well.
The boxed warning
Tirzepatide carries a boxed warning, which is the most serious warning the FDA applies. The exact text, with the brand name replaced in brackets:
“In rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether [tirzepatide] causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined.”
Read that carefully, because it is routinely misreported in both directions. It says the effect was observed in rats, and that whether it applies to humans is unknown. It does not say tirzepatide causes thyroid cancer in people. It also does not say it is safe.
What follows from it is a hard contraindication, covered below.
The most common side effects, with the actual numbers
Here is where most pages get it wrong. There are two sets of figures, because tirzepatide is approved for two different uses at different dose ranges, and the rates are not the same.
In the chronic weight management trials
| Adverse reaction | Incidence |
|---|---|
| Nausea | up to 29% |
| Diarrhea | up to 23% |
| Constipation | up to 17% |
| Vomiting | up to 13% |
| Abdominal pain | up to 10% |
| Dyspepsia (indigestion) | up to 10% |
| Injection site reactions | up to 8% |
| Fatigue | up to 7% |
| Hypersensitivity reactions | 5% |
| Eructation (burping) | up to 5% |
| Hair loss | up to 5% |
| Gastroesophageal reflux | 5% |
In the type 2 diabetes trials
| Adverse reaction | Incidence |
|---|---|
| Nausea | 12 to 18% |
| Diarrhea | 12 to 17% |
| Decreased appetite | 5 to 11% |
| Vomiting | 5 to 9% |
| Constipation | 6 to 7% |
| Dyspepsia | 5 to 8% |
| Abdominal pain | 5 to 6% |
Nausea at up to 29% in the weight management trials against 12 to 18% in the diabetes trials. Roughly double. The usual explanation is the dose range and how quickly it is escalated. It is worth knowing which set of numbers applies to why you are taking it.
The serious warnings
These are less common than nausea but they are the reasons the label exists. The FDA prescribing information lists the following under Warnings and Precautions:
- Risk of thyroid C-cell tumors
- Severe gastrointestinal adverse reactions
- Acute pancreatitis
- Acute gallbladder disease
- Acute kidney injury, generally from dehydration caused by vomiting or diarrhea
- Hypersensitivity reactions
- Hypoglycemia, particularly alongside insulin or insulin secretagogues
- Diabetic retinopathy complications in people with type 2 diabetes
- Suicidal behavior and ideation
- Pulmonary aspiration during general anesthesia or deep sedation
Two that people do not expect
Aspiration under anesthesia. These medications slow stomach emptying, which means the stomach may still contain food when it would normally be empty. Tell any surgeon, anesthetist or dentist that you take it, well before any procedure involving sedation. This is the single most actionable item on the page.
Kidney injury is usually secondary. It generally follows dehydration from vomiting or diarrhea rather than acting on the kidney directly. Which makes the boring advice, keep fluids up when the gut effects hit, more important than it sounds.
Who should not take it at all
The label lists two contraindications:
- A personal or family history of medullary thyroid carcinoma, or Multiple Endocrine Neoplasia syndrome type 2. This follows directly from the boxed warning and it includes family history, not just your own.
- Known serious hypersensitivity to tirzepatide or any ingredient in the formulation.
Family history is the one people skip on intake forms because they have not thought about it. It is worth asking relatives before you answer.
The hair loss line, since it surprises people
The weight management label reports hair loss in up to 5% of participants. It is in the table above, from the FDA document, not anecdote.
Rapid weight loss from any cause can trigger a temporary shedding phase, so it is not necessarily the molecule itself. If it is happening to you it is worth raising rather than assuming, and there is more on the mechanism and what is treatable in our hair loss guide.
What the label does not tell you
Being straight about the limits of this data:
- It says nothing about compounded versions. Covered at the top, and it is the most important caveat on this page.
- Incidence is not severity. Nausea at 29% covers everything from mildly off your food to unable to keep water down.
- Trial populations are not you. Participants were screened, monitored and supported in ways ordinary prescribing is not.
- Long term data is still accumulating. These are relatively new medications in weight management.
When to contact someone
Seek medical attention promptly for severe abdominal pain that may radiate to the back, particularly with vomiting, which is the pattern associated with pancreatitis. Also for difficulty breathing, swelling of the face, lips or throat, or hives.
Contact your prescriber for vomiting or diarrhea you cannot keep ahead of, signs of dehydration, vision changes if you have diabetes, or any change in mood or thinking. Adverse reactions can be reported to FDA MedWatch at 1-800-332-1088.
If you are having thoughts of harming yourself, this is worth telling someone about today rather than at your next appointment. Your prescriber can help, and in the US the 988 Suicide and Crisis Lifeline is available by call or text.
The head to head trial, which settles a question most pages get wrong
You will see the two drugs compared constantly by putting one label’s nausea figure next to the other’s. That comparison is not valid, because those numbers come from separate trials with different populations, escalation schedules and dose ranges.
There is no need to guess, because a direct head to head randomised trial exists. SURMOUNT-5, published in the New England Journal of Medicine in 2025, randomised 751 adults with obesity and without type 2 diabetes to maximum tolerated doses of either drug for 72 weeks.
What it found on weight
| Outcome | Tirzepatide | Semaglutide |
|---|---|---|
| Mean weight change at 72 weeks | -20.2% | -13.7% |
| Waist circumference change | -18.4 cm | -13.0 cm |
A difference of 6.5 percentage points, favouring tirzepatide, statistically significant.
What it found on side effects, which is the surprising part
| Adverse event | Tirzepatide | Semaglutide |
|---|---|---|
| Any adverse event | 76.7% | 79.0% |
| Nausea | 43.6% | 44.4% |
| Diarrhea | 23.5% | 23.4% |
| Constipation | 27.0% | 28.5% |
| Vomiting | 15.0% | 21.3% |
| Serious adverse event | 4.8% | 3.5% |
| Stopped because of a gastrointestinal side effect | 2.7% | 5.6% |
Nausea was essentially identical. 43.6% against 44.4%. Diarrhea and constipation were within a point of each other. Tirzepatide had noticeably less vomiting and roughly half the rate of people stopping because of gut effects. Serious adverse events were numerically higher with tirzepatide, though the trial was not designed to test that comparison.
Three honest caveats. The trial was open label, so neither participants nor investigators were blinded. It was funded by the manufacturer of one of the two drugs. And semaglutide was dosed to maximum tolerated rather than to a fixed dose. None of that invalidates it, and all of it belongs in any summary of it.
So the honest read: on weight reduction the trial favoured tirzepatide. On tolerability the two were much closer than the separate label tables suggest, and the gap that does exist is in vomiting and in how many people quit. Full figures for the other drug are in semaglutide side effects.
A 2026 meta-analysis of head to head studies covering 41,381 participants reached the same direction on weight, and found overall and gastrointestinal adverse events similar between the two, with serious adverse events more frequent with tirzepatide.
When they start, and whether they settle
The label reports incidence, not timing, so this section is about the pattern that shows up consistently in the trial data and in prescribing practice rather than a figure you can look up.
The gastrointestinal effects cluster around dose increases. That is the consistent observation. Someone tolerating a dose well will often see nausea return in the days after stepping up, then settle again. It is why escalation schedules are gradual rather than jumping to a target dose.
Most people who stop, stop early. Discontinuation in the trials concentrated in the first weeks. If the first month is manageable, the odds improve.
Some effects do not follow that pattern. Constipation tends to be a running issue rather than a spike after a dose change, and hair shedding, where it happens, usually appears months in rather than immediately, because that is how the hair cycle works.
What is usually done about the common ones
This is a description of what prescribing information and standard practice cover, not a set of instructions for you. Do not change a dose or schedule on your own.
Nausea, the one most people hit
- Slowing escalation. The most common adjustment, and the reason to tell your prescriber early rather than pushing through in silence.
- Smaller meals. These medications slow gastric emptying, so the volume that felt normal before may not now.
- Noticing what triggers it. High fat meals and large portions come up repeatedly in patient reports.
Vomiting and diarrhea, where the real risk sits
Not because they are worse to experience, but because acute kidney injury on this label is generally secondary to dehydration rather than a direct effect. Fluid intake stops being a comfort measure and becomes the thing that prevents the serious complication. Persistent vomiting is a call to your prescriber, not something to wait out.
Constipation
Fibre, fluid and movement are the standard first responses. Worth raising if it is persistent, because it is one of the effects most likely to still be there months in.
Common questions
Do the side effects mean it is working?
No. There is no established relationship between how sick you feel and how well a treatment is doing its job. That idea circulates widely and it is not supported by the label or the trial data.
Are compounded versions safer or worse?
Unknown, and anyone who tells you otherwise is guessing. Compounded preparations have not been through the trials that produced any of these figures. The active ingredient is the same molecule, which is a reasonable basis for expecting similar behaviour, but expectation is not evidence. What you can do is ask which pharmacy compounds it, what grade the ingredient is, and whether each lot is tested.
Can I drink alcohol on it?
The label does not contraindicate alcohol. It is worth raising with your prescriber anyway, since alcohol is itself hard on the stomach and can worsen dehydration if the gut effects are already active.
What happens if I stop?
A question for your prescriber rather than a page, because it depends on why you are taking it and for how long. It is a reasonable thing to ask before you start, alongside what would make them tell you to stop.
Questions worth asking your prescriber
- Given my history, particularly any thyroid or pancreatic issues, is this appropriate for me?
- What is the escalation schedule, and can we slow it if the gut effects are bad?
- At what point would you tell me to stop rather than push through?
- Is what I am being dispensed FDA approved or compounded, and which pharmacy makes it?
- What should I tell a surgeon or dentist before a procedure?
The fourth one matters more than it looks. Pricing for every plan is published on the pricing page before you start an intake.
Sources
This page cites two kinds of source and it is worth knowing the difference. Regulatory documents tell you what a drug label says. Peer reviewed trials tell you what was actually measured, in whom, and how well. Both are linked so you can check anything here against the original.
Regulatory
- FDA, Prescribing information for tirzepatide injection, chronic weight management indication. View source
- FDA, Prescribing information for tirzepatide injection, type 2 diabetes indication. View source
- FDA, Compounding and the FDA: Questions and Answers. View source
- FDA MedWatch, Safety Information and Adverse Event Reporting Program. View source
Peer reviewed literature
- Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med. 2025;393(1):26-36. Trial registration NCT05822830. https://doi.org/10.1056/NEJMoa2416394
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. Trial registration NCT04184622. https://doi.org/10.1056/NEJMoa2206038
- Ismaiel A, Scarlata GGM, Boitos I, et al. Gastrointestinal adverse events associated with GLP-1 RA in non-diabetic patients with overweight or obesity: a systematic review and network meta-analysis. Int J Obes. 2025;49(10):1946-1957. https://doi.org/10.1038/s41366-025-01859-6
- Pedersen SD, Manjoo P, Dash S, et al. Pharmacotherapy for obesity management in adults: 2025 clinical practice guideline update. CMAJ. 2025;197(27):E797-E809. https://doi.org/10.1503/cmaj.250502
Last reviewed 10 September 2026. Labels and evidence both change. If you are reading this well after that date, check the sources directly rather than relying on this page.
Related reading
More on medical weight loss:
- Online weight loss guide
- Compounded tirzepatide
- Compounded semaglutide versus tirzepatide
- Best online weight loss programs
- Weight loss clinic near me
- Hims weight loss review
- Semaglutide side effects
- Tirzepatide versus semaglutide
- Tirzepatide cost
Plans from PrescribedRX
PrescribedRX prescribes through clinicians licensed in your state. Plans in this category:
Every plan and its current price is on the plans page and the pricing page.
These are compounded preparations. Compounded drugs are not reviewed or approved by the FDA for safety or effectiveness, and treatment outcomes are not guaranteed.
This article is for general information. It is not medical advice and it is not a recommendation for any particular treatment. Whether a treatment is appropriate for you is a decision for a licensed clinician who has reviewed your health history and current medications.
