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Side effects

Headaches on a GLP-1 medicine

Headaches are common with or without a GLP-1 — which is exactly why the placebo figures matter here. The labels do report more of them on treatment, and the usual contributors are ones you can do something about: fluids, food and, for some people, blood sugar.

By the Cafeity teamUpdated 3 min read

The short answer

Headache is listed as a side effect on some GLP-1 labels, but the gap over placebo is modest: 14% on semaglutide 2.4 mg against 10% on placebo, 13.6% on liraglutide 3 mg against 12.6%, and 8–9% on orforglipron against 7%.123 Headache is not among tirzepatide's common reactions in its weight-management label. Common contributors are dehydration, eating much less, and — for people on insulin or a sulfonylurea — low blood sugar. A sudden severe headache, or one with vision changes, confusion or weakness, needs urgent care.

Bar chart of headache in the weight-management trials: Semaglutide 2.4 mg 14% versus 10% on placebo; Liraglutide 3 mg 13.6% versus 12.6% on placebo; Orforglipron 9% versus 7% on placebo.
Share of trial participants who reported headache, from each label. Tirzepatide's weight-management label does not list headache among its common reactions. Not a head-to-head comparison.

How common it is

Headache in placebo-controlled trials, from the current US prescribing information for each medicine. Rates from different medicines' trials are not directly comparable.
Medicine (trial population)PlaceboMedicine
Semaglutide 2.4 mg weekly injection (adults with obesity or overweight)10%14%
Semaglutide 7.2 mg weekly injection (adults with obesity)7%8% (2.4 mg), 9% (7.2 mg)
Liraglutide 3 mg daily injection (adults with overweight or obesity)12.6%13.6%
Orforglipron daily tablet (adults with obesity or overweight)7%8% (5.5 mg), 9% (9 mg), 9% (17.2 mg)
Liraglutide daily injection (type 2 diabetes) (adults with type 2 diabetes)7%11% (1.2 mg), 10% (1.8 mg)
Exenatide twice-daily injection (adults with type 2 diabetes)6%9%

Placebo groups report plenty of headaches too — 7% to 13% in these trials — so the extra attributable to the medicine is a few percentage points.

Likely contributors

  • Fluid. A smaller appetite and a lower thirst often mean drinking less; vomiting and diarrhoea make it worse.4
  • Eating much less, or going long stretches without food.
  • Low blood sugar in people taking insulin or a sulfonylurea — headache is among its listed signs.4
  • Changes in routine that often come with a new medicine — less caffeine, poorer sleep.

What tends to help

Regular meals and steady fluids through the day, rather than long gaps, are the general advice for people on these medicines, and they address the commonest contributors.5 For pain relief, ask a pharmacist which over-the-counter option suits you alongside your other medicines. Logging headaches with the time and what you had eaten and drunk often makes the trigger obvious within a couple of weeks.

When to contact your prescriber

Keeping a record of it

Log headaches with a severity and a time, on the same timeline as your doses, meals and fluids. After a few weeks the record shows whether it follows dose increases, particular foods or the days after an injection — and the Visit Summary puts that on one page for your prescriber.

Cafeity dose screen: an estimated medication-level curve labelled "Estimate based on published half-life. Not a measurement", the last dose, the injection site (stomach, lower left), a countdown to the next scheduled dose and a side-effect check-in.
A side-effect check-in under every dose.
Cafeity "Your week, understood" screen: Ora explains that everything is calculated from your own log, offers questions such as "When are my symptoms worst?", and shows the week's protein, energy, water, weight trend, symptom days and a note that protein was 80 g under target.
Ask when your symptoms are worst.

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Common questions

Do GLP-1 medicines cause headaches?
Headache is reported slightly more often than on placebo on some labels — for example 14% against 10% on semaglutide 2.4 mg.1 Dehydration and eating less are common contributors.
Why do I get a headache the day after my injection?
Some people find nausea and lower eating and drinking cluster in the day or two after an injection, which can bring headaches with them. A few weeks of logging will show whether that is your pattern.

Sources

  1. Semaglutide injection and tablets for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 30 June 2026
  2. Liraglutide 3 mg injection for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 15 June 2026
  3. Orforglipron tablets for weight management — US prescribing information DailyMed, US National Library of Medicine, version published 13 August 2026
  4. Tirzepatide injection for weight management and obstructive sleep apnoea — US prescribing information DailyMed, US National Library of Medicine, version published 2 September 2026
  5. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society Mozaffarian D et al. 2025 (published in four journals)

Written by the Cafeity team from the sources listed here. Figures from prescribing information are quoted as the label states them; trial results are averages from those trials, not predictions for any one person. This page has not yet been reviewed by a clinician — see the editorial policy for how pages are researched and corrected.