GLP-1 side effect rates, and why they cannot be compared

Why these four tables are not one table

A reader who wants to know whether semaglutide or tirzepatide causes more nausea is asking a reasonable question that these documents do not answer. The two diabetes labels report rates in patients with type 2 diabetes at a threshold of 5%; the two weight labels report rates in patients with obesity or overweight at a threshold of 2% and greater than placebo. A 44% in one table and an 18% in another describe different people, different doses and different counting rules.

Ozempic

The same section reports gastrointestinal adverse reactions overall at placebo 15.3%, Ozempic 0.5 mg 32.7% and Ozempic 1 mg 36.4%, and states that “the majority of reports of nausea, vomiting, and/or diarrhea occurred during dose escalation.” Discontinuation because of a gastrointestinal reaction: 0.4% on placebo, 3.1% on 0.5 mg, 3.8% on 1 mg.

Wegovy

Ten rows of a longer table, chosen as the ones a reader asks about; the label’s own table runs to nineteen. The fatigue and hair loss rows are broken out by dose and by sex on fatigue and hair loss. In these trials 6.8% of patients on Wegovy 2.4 mg and 3.2% on placebo permanently discontinued because of an adverse reaction — most often nausea (1.8% against 0.2%), vomiting (1.2% against 0%) and diarrhea (0.7% against 0.1%).

The label carries a second table for the 7.2 mg dosage, against both placebo and 2.4 mg. There, nausea is 13% on placebo, 35% on 2.4 mg and 39% on 7.2 mg, and dysesthesia — an abnormal sensation — is 0%, 6% and 22%.

Mounjaro

Zepbound

Eight rows of a sixteen-row table. The label ties its hair loss row to weight reduction, and it was reported mostly by women. The Zepbound label also quantifies the severe end: in a pool of two weight-reduction trials, severe gastrointestinal adverse reactions were reported in 1% on placebo, 1.7% on 5 mg, 2.5% on 10 mg and 3.1% on 15 mg. The same section states that Zepbound “is not recommended in patients with severe gastroparesis.”

What none of these tables tells you

They are trial rates, and every label says so itself, once, in the sentence quoted at the top of this page — the phrase “may not reflect the rates observed in practice” is the tail of that same sentence, not a second warning. Counted in each document: it occurs exactly once on each of the four. They describe selected populations followed for a fixed period under supervision, and they are the best-quality numbers that exist for these products. They are not a forecast for any individual, and nothing here turns them into one.

They also say nothing about compounded semaglutide or compounded tirzepatide, which have no approved label and no trial tables of their own. Related: the dose escalation schedules, which is where each label locates most of these reactions.

Sources

See the providers

Side effects are a property of the drug, not the seller. The boards list who sells it and what each one publishes.

• Semaglutide providersprovider board

  Compare semaglutide plans, pharmacy details and cancellation terms.

• Tirzepatide providersprovider board

  Compare tirzepatide plans, pharmacy details and cancellation terms.

More, read from the same labels

• First-year GLP-1 costsresearch guide

  A low monthly headline does not tell you what a year of treatment will cost. Compare the same medication and service package, then separate the total you expect to spend from the amount you must pay before treatment begins.

• Cancellation and refundsresearch guide

  Canceling future membership charges, stopping an upcoming medication order and requesting a refund are three different requests. Get a written answer for each one that applies to you.

• Insurance denial documentsresearch guide

  The next step depends on why coverage was denied. A missing document, a formulary restriction and an excluded benefit are different problems. Start with the written decision before paying someone to submit another request.

• Savings and cash-pay eligibilityresearch guide

  A manufacturer savings card and a self-pay offer can have different eligibility rules, even for the same medicine. Match the offer to your coverage and exact product before using its advertised price in your budget.

• Verify your GLP-1 pharmacyresearch guide

  The website taking your payment, the clinician prescribing and the pharmacy dispensing may be different businesses. Identify each one. A recognizable brand or a reassuring badge does not tell you who will fill the prescription.

• Changing GLP-1 providersresearch guide

  Before ending your current service, establish what the new practice needs, what it will charge and when it can evaluate you. Transferring your records does not guarantee that another clinician will continue the same prescription.

• Weight regain after stoppingresearch guide

  Weight regain occurred after treatment withdrawal in studies of semaglutide and tirzepatide. The findings support planning follow-up and affordability before an interruption, but they do not predict exactly what will happen to one person.

• Semaglutide vs tirzepatideresearch guide

  What the four FDA-approved labels say each molecule is, what each is approved to treat, and where the two differ.

• How they workresearch guide

  The receptor each molecule switches on, what the labels say that does to appetite, blood sugar and the stomach, and why one dose lasts a week.

• Is Ozempic insulin?research guide

  What the Ozempic label calls semaglutide, how that differs from insulin, and where insulin appears on these labels as a separate medicine.

• Zepbound vs Ozempicresearch guide

  Four brand names, two molecules and two kinds of approval: which of these products are the same drug, and what each one is actually approved to do.

• Dose escalation schedulesresearch guide

  The starting dose, the escalation interval and the maximum dose each label sets, and why they are not interchangeable.

• Hair lossresearch guide

  Which labels report hair loss, the rate against placebo where a trial measured it, and why two of them put no number on it.

• Fatigue and tirednessresearch guide

  Which labels list fatigue, the rate against placebo where a trial measured it, and what each label counts as fatigue.

• Missed dose rulesresearch guide

  The window each label gives for a late dose, and the minimum gap it requires when the injection day changes.

• Drug interactionsresearch guide

  Insulin and sulfonylureas, oral medications, and the oral-contraceptive precaution that appears on two of these four labels and not the other two.

• Buying one onlineresearch guide

  The agency's own warning signs for a telehealth GLP-1 seller, its 28-day vial rule, and what it says about drugs that arrive warm.

• Zepbound by doseresearch guide

  What each Zepbound dose achieved in the trials printed in its label, what the label says about choosing a maintenance dose, and what the higher doses cost in side effects.

• Zepbound at 3 monthsresearch guide

  What does the Zepbound label report about three-month weight loss and maintenance dosing?

• Injecting tirzepatideresearch guide

  The injection sites, the rotation rule and the steps for the single-dose pen, the KwikPen and the vial and syringe, exactly as the FDA-approved Instructions for Use give them.

• Refrigeration and storageresearch guide

  How cold each pen is kept, how many days it can spend at room temperature, and what the labels say about heat and freezing.

• Who should not take oneresearch guide

  The boxed warning every one of these labels carries, the two contraindications, and which warnings appear on which product.