Mounjaro Headaches: What Causes Them & How to Manage Them

Any medication can cause side effects and Mounjaro is no exception. If you’ve started getting headaches on Mounjaro, you probably want to know why, and what you can do to get some relief.

Here’s our guide to why headaches are a common side effect and how to prevent headaches on Mounjaro.

Can Mounjaro Cause Headaches?

Yes, Mounjaro (tirzepatide) can cause headaches. They’re listed as a side effect in Wegovy’s Patient Information Leaflet.

Headaches are also included as a symptom of low blood sugar (hypoglycaemia). This can occur when taking Mounjaro, particularly if you are taking specific medications for type 2 diabetes.

Side effects are a normal part of taking most medications. And the side effects of Mounjaro usually improve once your body adjusts to the medication. 

The side effects you experience, and how severely you experience them, can also vary from person to person.

Let’s find out more about the causes of Mounjaro headaches.

What Causes Headaches on Mounjaro?

There are a number of reasons why you might experience headaches when taking Mounjaro.

The Medication

Some patients on Mounjaro have noticed they get worse headaches, or experience them more often, when starting treatment. 

One possible reason for this is that Mounjaro can affect the brain and the blood vessels in the head. It may cause blood vessels to relax and widen, which may trigger a headache. The treatment may also change how the nervous system processes pain, which may make some patients more sensitive to headaches.

The good news is that most patients usually experience this side effect early on. It usually goes away on its own as the body adjusts to the medication.

Blood Sugar Fluctuations   

Your blood sugar level, also known as your glucose level, refers to the concentration of sugar in your blood. It’s controlled by a hormone called insulin and it’s affected by two different things:

1. The food you eat
2. The amount of cellular energy your body uses

It’s fairly normal for your blood sugar levels to go up and down during the day. They normally rise after you eat and then drop again once you’ve used this sugar for energy.

Mounjaro is a GLP-1 receptor agonist. It was first developed as a medication for diabetes. Diabetes is a condition that occurs if your body doesn’t respond to insulin properly. It works by improving your body’s sensitivity to insulin and lowering your blood glucose levels.

Studies have found that taking Mounjaro with insulin-based medications increases your risk of developing low blood sugar. This means that you could be at increased risk of experiencing the symptoms associated with low blood sugar. One of these symptoms is headaches.

Dehydration

How much have you had to drink today? Not drinking enough water might be causing your headaches. And staying hydrated is particularly important on GLP-1 weight loss medications.

Although Mounjaro is an appetite suppressant, many people taking the medication have also reported feeling much less thirsty too.

This is likely to be because hunger and thirst can often feel similar. Your hypothalamus, which is the part of your brain that regulates these needs, can misinterpret the two. Sometimes when you feel hungry and have a glass of water, you may realise that you were actually thirsty instead.

Mounjaro turns off the “food noise” that can cause you to eat more food that you actually need (helping you lose weight). But this can also switch off the desire to drink in people taking Mounjaro.

Dehydration happens when your body uses more fluid than you drink. In the short term it can cause some unpleasant symptoms. But if this continues, it could become serious.

Dehydration headaches happen because your brain (along with other tissues in your body) shrinks when you don’t have enough fluid in your body. When this happens, it pulls away from your skull, and this can cause the discomfort you associate with a headache.

Side-Effect-Induced Stress

Did you know that stress can trigger headaches?

There are lots of other side effects associated with taking Mounjaro. Some of the most common include nausea, vomiting and diarrhoea. These types of side effects can put your body under a great deal of stress and strain.

Studies have shown that stress is a key cause of headaches. This is because it can trigger a physical response, including muscle contractions, which affect the scalp and brain.

This is part of your natural “fight or flight” response to episodes of severe stress. It increases your brain’s sensitivity to pain and could contribute to headaches. 

Stomach issues are common on Mounjaro. So it would make sense that headaches caused by the stress of digestive issues could occur.

Moving to a Higher Dose of Mounjaro

When you start Mounjaro, you start on the 2.5 mg dose. However, as you progress through your weight loss journey, you’ll probably need to start moving up through the doses of the medication.

This is known as titration. It enables your body to gradually get used to the side effects associated with the medication. This should make them easier to tolerate and help you stay on your medication. It’s particularly important for drugs that can have significant side effects.

However, as you titrate upwards through the different doses of Mounjaro, you may also notice a temporary increase in these side effects^.  This happens as your body gets used to the increased amount in your system.

These usually settle down after a week or so. But as you move through your Mounjaro journey, you may experience headaches when you titrate to a new dose.

Titration is a careful balance of ensuring your side effects are manageable and that medication is effective. This is one of the main reasons you’ll need to have regular reviews with your prescribing team.

They’ll ask you questions about how much weight you’ve lost and how bad your side effects are. This can help them recommend the most suitable dose of Mounjaro for your needs.

How to Prevent & Manage Headaches on Mounjaro

Okay, so how to get rid of Mounjaro headaches? The good news is that, by identifying the main reasons why you have a headache on Mounjaro, you can take steps to manage and prevent them.

Make Sure You’re Well Hydrated

This is probably the easiest fix for Mounjaro headaches. We know it can be tough to eat and drink when you don’t feel like it. But drinking plenty of water can help prevent a range of side effects, including headaches.

Water is obviously best. But low/no-added sugar squash is a great alternative if you want to add flavour. Aim for 6 to 8 glasses each day at least, as per the guidelines from the NHS.

Just remember that drinking alcohol can actually dehydrate you and could make headaches worse.

Consider Adding Electrolytes to Your Drinks

If you’re struggling to drink enough water during the day, you could think about using electrolytes to boost your natural hydration levels.

They’re usually made of sodium, potassium, magnesium and chloride. They hydrate your body by helping water to stay in your cells rather than just passing through them.

There are a wide range of products containing electrolytes available. So it’s easy to find one to suit your personal tastes.

Eat Smaller, More Frequent Meals

If you think that your Mounjaro headaches are caused by low blood sugar, changing your eating pattern could help. Choosing to have smaller meals more frequently, and not skipping meals, is effective at keeping blood sugar levels more stable.

Similarly, research suggests that managing your carbohydrate intake can contribute to better blood glucose control. This may help reduce the risk of experiencing some side effects from sudden fluctuations in your blood sugar levels.

It’s important to focus on a balanced diet that includes a variety of foods to support overall health.

Take Pain Relief

If other methods aren’t helping, you may be able to get Mounjaro headache relief by taking over-the-counter pain medications.

However, we recommend that you always speak to your prescriber or a pharmacist first to make sure that they would recommend this course of treatment. They may have a particular type of pain-relieving medication that they would recommend.

When to Seek Medical Advice

For the majority of people, headaches caused by taking Mounjaro are mild. And they usually go away by themselves in a few days or with pain medication. However, there are times when we would strongly advise that you seek prompt or urgent medical attention.

If you experience:

·      Severe, persistent headaches lasting more than three days

·      Vision changes

·      Pain that is accompanied by fever or vomiting

·      Sudden, severe head pain

·      Confusion, difficulty speaking or other neurological symptoms

You should seek medical help right away. If you can’t get hold of your prescriber, visit your GP, call 111 or visit your local Accident and Emergency department.

If you have general concerns about managing headaches while taking Mounjaro, our friendly and dedicated team is here and ready to help. Please get in touch.

You can report any side effects to the UK medicines regulator’s (the MHRA) Yellow Card scheme. The scheme helps the MHRA spot new safety issues early and take action, like updating safety advice or warnings.

References

Patient Information Leaflet. Mounjaro KwikPen (all doses). Available from: https://www.medicines.org.uk/emc/files/pil.15481.pdf Accessed February 2026.

NHS Webpages. Insulin for Type 2 Diabetes. Available from: https://www.nhs.uk/medicines/insulin/insulin-for-type-2-diabetes/ Accessed February 2026.

Lana Gettman. New Drug: Tirzepatide (Mounjaroä ). PMID: 36751934. Available from: https://pubmed.ncbi.nlm.nih.gov/36751934/.

Diabetes UK. What is Mounjaro? Uses, How it Works and Side Effects. Available from: https://www.diabetes.org.uk/about-diabetes/looking-after-diabetes/treatments/tablets-and-medication/glp-1/mounjaro.

National Institute of Diabetes and Digestive and Kidney Diseases. Low Blood Glucose (Hypoglycaemia). Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia Accessed February 2026. 

Fiona McKiernan, Jenny A Houchins, Richard David Mattes. 2008. Relationships between human thirst, hunger, drinking and feeding. Available from: https://www.researchgate.net/publication/5351365_Relationships_between_human_thirst_hunger_drinking_and_feeding.

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Aleksander Sic, Marko Bogicevic, Neboisa Brezic, Clara Nemr, Nebojsa Nick Knezevic. 2025. Chronic Stress and Headaches: The Role of the HPA Axis and Autonomic Nervous System. PMID: 40002876. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11852498/.

Hadi A Almansour, Hilal A Thaibah, Moaddey Alfarhan, Saeed A-Al Qahtani, Amani A Khardali, Thamir M Alshammari. 2025. Real-World Safety Concerns of Tirzepatide: A Retrospective Analysis of FAERS Data (2022-2025). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12469573/.

NHS. Water, drinks and hydration. Available from: https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/water-drinks-nutrition/ Accessed February 2026.

UK Health Security Agency. Minimum amount of alcohol to cause dehydration: A rapid evidence summary. Available from: https://assets.publishing.service.gov.uk/media/6932d5954bedc0e76230414a/Minimum-amount-of-alcohol-to-cause-dehydration-rapid-evidence-summary.pdf.

Mindy Millard-Stafford, Teresa K Snow, Michael L Jones, HyunGyu Suh. 2021. The Beverage Hydration Index: Influence of Electrolytes, Carbohydrate and Protein. PMID: 34578811. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8465972/.

Michael E. Holmstrup, Christopher M. Owens, Timothy J. Fairchild, Jill A. Kanaley. 2010. Effect of meal frequency on glucose and insulin excursions over the course of the day. Available from: https://www.clinicalnutritionespen.com/article/s1751-4991(10)00054-5/fulltext.

University Hospitals Coventry and Warwickshire NHS Trust. Diabetes: Reducing Carbohydrates. Available from: https://www.uhcw.nhs.uk/download/clientfiles/files/Patient%20Information%20Leaflets/Clinical%20Support%20Services/Dietetics/Diabetes%20-%20Reducing%20Carbohydrates.pdf Accessed February 2026.

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