Who the labels say should not take a GLP-1

The boxed warning

Every one of these four labels carries a boxed warning, the strongest warning the FDA applies, and all four carry the same one, headed WARNING: RISK OF THYROID C-CELL TUMORS.

Mounjaro’s, in full as the label states it: “In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether MOUNJARO 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”.

The semaglutide labels say the same thing about their own molecule. Ozempic: “In rodents, semaglutide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether OZEMPIC causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of semaglutide-induced rodent thyroid C-cell tumors has not been determined”.

Two things in that wording are worth reading precisely, because they are usually paraphrased away. The finding is in rodents. And the labels say the human relevance of that finding has not been determined — not that it has been ruled out, and not that it has been established.

Each boxed warning then adds the same practical instruction: counsel patients about the symptoms of thyroid tumors — “a mass in the neck, dysphagia, dyspnea, persistent hoarseness” — and note that “routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC” in patients taking these drugs.

The contraindications

Section 4 is the short list — the circumstances in which the label says the drug should not be used at all. On all four it holds the same two entries.

Which warnings appear on which label

Section 5 is longer and it is not identical across the four. The table below lists the subsection titles in each label’s warnings and precautions section, read end to end in September 2026. A blank is an absence from that document, not a statement that the risk does not exist.

The cells hold the subsection number in that label, so a reader can go to the document and check. 11 warnings appear across the four; 10 are shared, and heart rate increase appears on the Wegovy label alone among these four. Read down the columns instead of across the rows, the four sections run to 10 on Ozempic, 11 on Wegovy, 10 on Mounjaro and 10 on Zepbound.

Pregnancy, and a number that only two of these labels give

Both semaglutide labels give a discontinuation interval before a planned pregnancy. Neither tirzepatide label gives one. That is a real difference between the documents, and the semaglutide interval is not borrowed across to fill the empty cells.

The semaglutide labels’ two months is not carried across to tirzepatide. The two molecules clear at different rates, and each label states the interval as following from its own. Both tirzepatide labels do carry the oral-contraceptive precaution described on the drug interactions page, which is a different question and is often confused with this one.

Sources

See the providers

If none of these warnings rule the drug out for you, the boards list the providers who prescribe 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.

• Side effect ratesresearch guide

  What each label reports for nausea, vomiting, diarrhea and constipation — and the sentence every label prints above those numbers.

• 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.