Which has fewer side effects, tirzepatide or semaglutide?

Neither has fewer side effects in every comparison. In SURMOUNT-5, nausea, diarrhea and constipation rates were nearly identical, while vomiting and treatment discontinuation for adverse events were lower with tirzepatide. In SURPASS-2, adverse-event discontinuation was higher with each tirzepatide dose than with semaglutide 1 mg. Individual response and dose matter.

Does tirzepatide cause more nausea than semaglutide?

Not consistently. SURMOUNT-5 reported nausea in 43.6% of participants taking tirzepatide and 44.4% taking semaglutide. In SURPASS-2, nausea ranged from 17.4% to 22.1% across tirzepatide doses and was 17.9% with semaglutide 1 mg. The study population and maintenance dose change the comparison.

Why are side-effect rates higher in SURMOUNT-5 than SURPASS-2?

The trials used different populations, doses and durations. SURMOUNT-5 studied maximum tolerated obesity doses for 72 weeks in adults without diabetes. SURPASS-2 studied tirzepatide 5, 10 or 15 mg against semaglutide 1 mg for 40 weeks in adults with type 2 diabetes. Rates from those settings are not directly interchangeable.

Do tirzepatide and semaglutide side effects get better over time?

Often, but not always. Both direct trials found that most gastrointestinal events were mild to moderate and occurred mainly during dose escalation. Persistent or worsening symptoms still need clinical review, especially if they impair hydration or nutrition. A prescriber can decide whether the dose, timing or medication should change.

Can switching from semaglutide to tirzepatide reduce side effects?

It may for an individual, but the evidence cannot predict that outcome. SURMOUNT-5 favored tirzepatide for vomiting and discontinuation, yet nausea, diarrhea and constipation were nearly identical. A switch also starts a new tolerability question, so the decision should account for current symptoms, dose, other medications and medical history.

Are Promise's compounded versions approved medications?

No. FDA-approved versions of these molecules exist, but the compounded formulations offered here are not FDA-approved. They are prescribed for an individual patient and dispensed by a licensed U.S. compounding pharmacy. A provider weighs whether a compounded formulation is appropriate; regulatory status is one part of that patient-specific decision.

Tirzepatide vs Semaglutide Side Effects

Tirzepatide vs semaglutide side effects are close enough that neither medication is the universal tolerability winner. In a 2025 obesity trial, nausea and diarrhea rates were nearly identical, while vomiting and side-effect discontinuations were lower with tirzepatide. In a 2021 diabetes trial, higher tirzepatide doses produced somewhat more nausea and more discontinuations than semaglutide 1 mg. Dose, escalation and the individual response all matter. The broader tirzepatide versus semaglutide comparison covers mechanism, outcomes and cost; this comparison stays with tolerability.

Tirzepatide vs semaglutide side effects at a glance

The two direct trials answer different versions of the question. SURPASS-2 compared three fixed maintenance doses of tirzepatide with semaglutide 1 mg in adults with type 2 diabetes for 40 weeks. SURMOUNT-5 compared each medication at its maximum tolerated obesity dose in adults without diabetes for 72 weeks. The latter meant tirzepatide 10 or 15 mg and semaglutide 1.7 or 2.4 mg.

Trial and arm	Nausea	Diarrhea	Vomiting	Constipation	Stopped treatment for any AE
SURPASS-2: tirzepatide 5 mg	17.4%	13.2%	5.7%	6.8%	6.0%
SURPASS-2: tirzepatide 10 mg	19.2%	16.4%	8.5%	4.5%	8.5%
SURPASS-2: tirzepatide 15 mg	22.1%	13.8%	9.8%	4.5%	8.5%
SURPASS-2: semaglutide 1 mg	17.9%	11.5%	8.3%	5.8%	4.1%
SURMOUNT-5: tirzepatide maximum tolerated dose	43.6%	23.5%	15.0%	27.0%	6.1%
SURMOUNT-5: semaglutide maximum tolerated dose	44.4%	23.4%	21.3%	28.5%	8.0%

Rates are percentages of participants, not comparisons against placebo. The sources are SURPASS-2 in the New England Journal of Medicine, 2021 and SURMOUNT-5 in the New England Journal of Medicine, 2025. In SURMOUNT-5, gastrointestinal events specifically led 2.7% of the tirzepatide group and 5.6% of the semaglutide group to stop treatment. Both trials described most gastrointestinal events as mild to moderate and concentrated during dose escalation.

Why the trial rates look so different

SURPASS-2 does not show what happens when both medications are used at their obesity maintenance doses. Its semaglutide comparison stopped at 1 mg, while SURMOUNT-5 allowed 1.7 or 2.4 mg. SURMOUNT-5 also enrolled people without diabetes and ran almost twice as long. Those differences make it misleading to place a SURPASS-2 rate beside a SURMOUNT-5 rate as though the populations and exposure were interchangeable.

Within SURPASS-2, nausea rose from 17.4% at tirzepatide 5 mg to 22.1% at 15 mg. Discontinuation for any adverse event rose from 6.0% to 8.5%. That is useful evidence that the maintenance dose can change tolerability, but it does not predict which molecule a particular person will tolerate better. The separate tirzepatide side-effects guide and semaglutide side-effects guide cover each medication's full safety profile.

What routine-care data add

Trials actively collect symptoms; medical claims capture diagnoses serious enough to generate care. They answer different questions. A 2024 JAMA Internal Medicine cohort matched 18,386 adults using formulations labeled for type 2 diabetes and found similar rates of recorded gastrointestinal adverse events with the two drugs.

As of September 2026, a larger Annals of Internal Medicine claims study matched 46,620 pairs of adults with type 2 diabetes. For a composite of acute pancreatitis, biliary disease, bowel obstruction, gastroparesis and severe constipation, tirzepatide versus semaglutide had a hazard ratio of 1.07, with a 95% confidence interval from 0.90 to 1.26. Because that interval includes 1, the study did not establish a difference in these severe gastrointestinal outcomes. Residual differences between patients can remain even after statistical matching.

Which has fewer side effects in practice?

The most defensible answer is: whichever one a person can stay on at a clinically useful, tolerable dose. SURMOUNT-5 slightly favored tirzepatide on vomiting and discontinuation, but nausea, diarrhea and constipation were nearly the same. SURPASS-2 showed no clean winner across symptoms, and its adverse-event discontinuation rate was higher in every tirzepatide arm than in the semaglutide arm.

The dose-escalation period deserves more attention than the drug name alone. A person who feels well at one maintenance level may develop symptoms after an increase. A prescriber can weigh symptom timing, hydration, other medicines and whether holding at a tolerated level makes more sense than continuing escalation. The prescriber sets the dose; trial schedules are not personal instructions. For the usual pattern and duration, see how long GLP-1 nausea lasts.

When tolerability changes the plan

A brief wave of nausea is different from repeated vomiting or an inability to keep fluids down. Persistent vomiting, signs of dehydration, severe or continuing abdominal pain, abdominal swelling with inability to pass stool or gas, yellowing of the skin or eyes, or symptoms of a serious allergic reaction merit prompt medical evaluation. Side effects that interfere with eating, drinking, work or sleep are also worth reporting before the next dose decision.

Switching molecules may help an individual, but the head-to-head evidence cannot promise that it will. Both medicines share a gastrointestinal-heavy adverse-event pattern, and the 2026 claims data did not separate them on severe gastrointestinal outcomes. A clinician can decide whether the better next move is more time at the current dose, a different dose, a switch or stopping treatment.

The prescription route still matters

Through Promise, tirzepatide and semaglutide are dispensed as compounded medications, which are different from FDA-approved products: the formulations offered here are not FDA-approved. A licensed provider may still prescribe a compounded formulation; that decision is between the patient and doctor.

At Promise, a licensed provider reviews every request and not everyone qualifies. The same clinical relationship is where tolerability belongs: the useful comparison is not only which rate is lower in a table, but which option fits the person's history, other medications and response over time.