Headaches on Mounjaro: What to Know and How to Track Them

Headaches on Mounjaro are listed among the commonly reported side effects of tirzepatide. They tend to appear most often in the first few days after an injection — especially following a dose increase — and often settle within a day or two as your body adapts.

Possible contributing factors

Several things may play a role in headaches during a GLP-1 or dual GIP/GLP-1 journey:

• Reduced appetite and lower food intake: Eating significantly less than usual can mean fewer calories and carbohydrates, which some people find contributes to low-level headaches, particularly early on.
• Hydration: Lower appetite can also mean drinking less than usual without realising it. Many people on Mounjaro find that staying on top of water intake makes a noticeable difference.
• Slower gastric emptying: Mounjaro slows the rate at which the stomach empties, which can affect how and when nutrients and fluids reach the body.
• Dose adjustment periods: Titration — moving to a higher dose strength — is a common trigger point, and headaches reported at this stage often ease within a week or so.

It is worth noting that headaches are also commonly reported by people taking Wegovy (semaglutide), suggesting the GLP-1 mechanism itself may be a factor for some. You can read more in our guide to headaches and Wegovy if you are curious about how experiences compare across the two medicines.

For a broader look at what people commonly experience on tirzepatide, the Mounjaro side effects overview covers the full picture. And if you are dealing with more than one symptom at the same time — for example, constipation is another commonly reported experience — our page on being constipated on Mounjaro may also be useful.

One of the most practical things you can do when a side effect like headaches keeps appearing is to log it consistently, so you can spot your own patterns and have an informed conversation with your prescriber.

GLP Trackr's side-effect tracker lets you note symptoms like headaches each day, recording when they occur, how intense they feel, and how long they last. Over time, the app can reveal whether your headaches cluster around injection day, peak at certain dose stages, or correlate with how much water you have logged that day. That kind of personal data is difficult to piece together from memory — but straightforward when it is captured in one place.

Alongside side-effect logging, the daily check-in captures water intake and energy levels each morning, which can help you see whether hydration patterns connect to how you feel. If headaches have been a recurring theme, the doctor report feature can pull your logged data into a clear summary to bring to your next prescriber appointment — so nothing gets forgotten in the moment.

If you want a clear record of your headache pattern alongside your injection schedule, GLP Trackr is free to try for 7 days — available now on the App Store and Google Play.

It is also worth exploring our page on whether Mounjaro can cause headaches for more background on this topic.

If your headaches are severe, come on suddenly, or are different from anything you have experienced before, please contact your healthcare professional promptly. 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, and any concern about your symptoms should always go to them first.