Can Wegovy Cause Headaches?

Wegovy works by activating GLP-1 receptors, which are involved in appetite regulation, insulin response, and the rate at which the stomach empties. These physiological changes — particularly in the early stages of treatment or following a dose increase — are thought to contribute to headaches in some people, though the exact mechanism is not fully established.

Possible contributing factors

• Reduced food and fluid intake: Because Wegovy can significantly lower appetite, some people eat and drink less than usual, especially in the first days after an injection. Mild dehydration or lower calorie intake are commonly cited triggers for headaches in general.
• Blood sugar fluctuations: Changes in eating patterns and GLP-1 activity may affect blood glucose levels, which some people associate with head pain or a "foggy" feeling.
• Dose adjustment periods: Headaches are reported more often around the time of dose increases, as the body adjusts to a higher level of semaglutide. They often ease once the body acclimatises.

According to the electronic Medicines Compendium (eMC) product information for Wegovy, headache is listed among the commonly reported side effects. You can review the full side-effect profile in the Wegovy Summary of Product Characteristics on medicines.org.uk.

If you are also curious about how headaches are reported by people taking tirzepatide, see our page on headaches on Mounjaro for a comparison. Other commonly reported side effects worth knowing about include diarrhoea on Wegovy and hair changes on Wegovy.

One of the most useful things you can do when experiencing a recurring symptom like headaches is to log it consistently — noting when it starts, how severe it feels, and what else is happening that day (hydration, food intake, sleep, where you are in your injection cycle). Over time, patterns often emerge that are hard to spot from memory alone.

GLP Trackr's side-effect tracker lets you log symptoms like headaches with a severity rating each day, creating a timeline you can bring to your next appointment. Alongside that, the daily check-in captures water intake, sleep, and energy levels — context that can help you and your prescriber identify whether a particular factor (low hydration, disrupted sleep) tends to coincide with your headaches. If a pattern does appear, it is genuinely useful information to share.

You can also use the app's dose logging feature to note exactly when each injection was taken, so you can see whether headaches cluster around injection day or dose-increase periods.

Start logging your symptoms and spotting your own patterns — GLP Trackr is free to try for 7 days on the App Store and Google Play. It takes only a few seconds per day, and the data you build up belongs entirely to you.

For a broader look at side effects people commonly experience on GLP-1 medicines, visit our guide to GLP-1 side effects.

A note on safety: GLP Trackr helps you record what you are experiencing so you can discuss it with your prescriber — it is not a substitute for their guidance. If your headaches are severe, persistent, or accompanied by other symptoms that concern you, contact your healthcare professional promptly. Any decision about your dose or treatment should be made with your prescriber, not on your own. If you experience a side effect you want to report formally, you can do so through your national reporting scheme (such as the UK's Yellow Card scheme) or by speaking with your healthcare professional.