GLP-1 Headache: What the Zepbound, Wegovy, Ozempic and Mounjaro Labels Record, How Much of It Placebo Matched, and Why Neurologists Are Testing These Drugs for Headache

Headache is the GLP-1 side effect where placebo does most of the work. In the Wegovy weight-loss trials, 14% of people on the drug reported a headache at some point — and so did 10% of people on dummy injections. In every placebo-controlled table that prints headache for a GLP-1 medicine, the gap between drug and placebo is between one and four percentage points. Several labels print no headache rate at all.

This page sets out what each of nine current US labels records, the placebo figure beside it, and what the medical literature says — which, unusually for a side effect, is mostly about GLP-1 drugs as a possible treatment for a headache disorder. The labels were read on 11 October 2026 from DailyMed, using the manufacturers' own versions. It reports what the documents record and does not advise on treatment; a new, severe or persistent headache is a reason to speak to a prescriber.

The rate in every current label

The "excess" column is glp1ledger's subtraction — the drug rate minus the placebo rate in the same table — which no label prints.

What "not listed" means differs by label, and it matters:

• Zepbound's table includes every reaction reported by at least 2% of people on the drug and more often than on placebo. Headache's absence therefore means it failed one of those two tests — either it was rarer than 2%, or no more common than on placebo. The label does not say which.
• Mounjaro's table has a 5% cut-off, and the text beneath it, which lists several less common stomach reactions, does not mention headache.
• Ozempic and the semaglutide tablets list headache only under postmarketing experience — reports from routine use, which the labels say cannot be counted reliably or attributed to the drug. Neither prints a trial rate.

So the answer to "does it cause headaches" depends on the document read. For the semaglutide weight-loss injection, the trials recorded a small excess; for tirzepatide, the trial tables record none above their threshold.

Why the placebo figures are so high

Headache is one of the most common symptoms in everyday life, and these trials ran for a year or more and counted any headache reported at least once. That is why one in ten people on placebo in the Wegovy trials, and one in six adolescents, reported a headache. The drug's contribution is the gap, and the gap is small. Compare nausea in the same Wegovy table — 44% on the drug against 16% on placebo, a 28-point excess — or constipation, at 13 points.

The low-blood-sugar connection

Headache appears in a second place on almost every GLP-1 label: in the patient information's list of signs of low blood sugar, alongside dizziness, sweating, shakiness, confusion, blurred vision and a fast heartbeat. The labels warn that the risk of low blood sugar rises when a GLP-1 medicine is taken with insulin or a sulfonylurea. On its own a GLP-1 medicine rarely lowers blood sugar too far, because its effect on insulin depends on glucose being high; the combination is where the labels place the risk. A headache in that setting is a different signal from the background headaches counted in the tables above.

The labels' fluid-loss warning is the other link people draw: diarrhoea and vomiting can cause dehydration, which the labels connect to kidney injury. No label connects it to headache, and this page does not either. The fluid-loss figures are on GLP-1 diarrhoea.

The literature runs the other way

A PubMed search run on 11 October 2026 for the main GLP-1 drug names together with "headache" returned 67 records; the same drug names with "migraine" or "idiopathic intracranial hypertension" returned 40. Most of that literature is not about headache as a side effect. It is about idiopathic intracranial hypertension (IIH) — a condition in which pressure inside the skull rises, causing headaches and swelling of the optic nerve that can threaten sight. The randomised trial below enrolled women with obesity (mean body-mass index 38.1).

• The first randomised trial. In 2023, a placebo-controlled trial in 16 women with active IIH (15 completed) measured pressure directly with implanted monitors. Exenatide — the first GLP-1 drug, derived from a lizard's venom — lowered intracranial pressure by 5.7 cmCSF at 2.5 hours, 6.4 at 24 hours and 5.6 at 12 weeks against placebo, from a baseline of about 30.6 (Mitchell et al., Brain).
• The 2025 meta-analysis. Pooling two trials and two registries, 1,550 patients in all, researchers reported that GLP-1 and dual GIP/GLP-1 drugs were associated with lower risk of papilloedema (swelling of the optic nerve), fewer visual problems, and 3.64 fewer monthly headache days at three months. The reduction in the risk of headache itself (RR 0.61, 95% CI 0.34–1.07) did not reach statistical significance, and the authors call for well-designed randomised trials (Stefanou et al., European Journal of Neurology).

Neither result is an approved use of any GLP-1 medicine, and the evidence is small. But it means the question "do these drugs cause headaches" has an unusual neighbour in the research record: for one headache disorder, they are being tested as the treatment.

What this page cannot tell you

• The rates count anyone who reported a headache at least once, of any severity and any cause, over trials lasting a year or more.
• The excess figures are subtractions within one table, not adjusted estimates; differences of one or two points are within the range chance alone produces in trials of this size.
• A label that does not list headache has not shown the drug never causes one. It shows only that the trial tables did not record it above their threshold.
• No trial compared two GLP-1 drugs for headache, so the table ranks nothing.
• The IIH research concerns one condition. It says nothing about whether a GLP-1 medicine affects migraine or ordinary tension headaches.

Whether a headache on a particular medicine needs investigating is a decision for the prescriber. Every other side effect in the class is set out on GLP-1 side effects, with the brand pages for Wegovy and Zepbound.

Sources

• Prescribing information read on DailyMed, 2026-10-11 (manufacturer label versions, effective dates as shown): WEGOVY (Novo Nordisk, set ID ee06186f-2aa3-4990-a760-757579d8f77b), adult, 7.2 mg and adolescent adverse-reaction tables and Medication Guide; SAXENDA (Novo Nordisk, 3946d389-0926-4f77-a708-0acb8153b143), Table 2; FOUNDAYO (Eli Lilly, 8ac446c5-feba-474f-a103-23facb9b5c62), Table 1; VICTOZA (Novo Nordisk, 5a9ef4ea-c76a-4d34-a604-27c5b505f5a4), Table 1; ZEPBOUND (Eli Lilly, 487cd7e7-434c-4925-99fa-aa80b1cc776b), Table 1 and Medication Guide; MOUNJARO (Eli Lilly, d2d7da5d-ad07-4228-955f-cf7e355c8cc0), Table 1 and section 6.1; OZEMPIC injection (Novo Nordisk, adec4fd2-6858-4c99-91d4-531f5f2a2d79), section 6.2; semaglutide tablets, OZEMPIC/RYBELSUS (Novo Nordisk, 27f15fac-7d98-4114-a2ec-92494a91da98), section 6.2; TRULICITY (Eli Lilly, 463050bd-2b1c-40f5-b3c3-0a04bb433309), section 6. All at dailymed.nlm.nih.gov.
• Mitchell JL, Lyons HS, Walker JK, et al., "The effect of GLP-1RA exenatide on idiopathic intracranial hypertension: a randomized clinical trial", Brain 2023;146:1821–1830, PMC10151178.
• Stefanou MI, Chatziralli I, Lambadiari V, et al., "Efficacy and Safety of GLP-1 and Dual GIP/GLP-1 Receptor Agonists in Idiopathic Intracranial Hypertension: A Systematic Review and Meta-Analysis", European Journal of Neurology 2025;32:e70358, PMC12426903.
• PubMed searches run 2026-10-11 through NCBI E-utilities: (semaglutide OR tirzepatide OR liraglutide OR "GLP-1 receptor agonist") AND headache (67 records); the same drug terms AND (migraine OR "idiopathic intracranial hypertension") (40 records).