Feeling dizzy or lightheaded can be unsettling, especially when you’re already adjusting to treatment. Dizziness is a recognised side effect of Mounjaro, so if it’s something you’ve experienced, you’re not alone.

While nausea, diarrhoea and constipation are often talked about as common Mounjaro side effects, dizziness can sometimes catch you by surprise. And when you don’t know why it’s happening, it’s natural to wonder whether it’s something you should be concerned about.

Understanding what could be behind your dizziness and knowing what to do when it happens can help you feel more prepared. We’ll explain why Mounjaro may make you feel dizzy, how to manage light-headedness safely, and when your symptoms may need medical attention.

Why does Mounjaro cause dizziness?

There isn’t necessarily one single explanation for feeling dizzy while taking Mounjaro. Dizziness itself is recognised as a common side effect of tirzepatide, the active ingredient in Mounjaro. Tirzepatide also affects appetite and blood glucose levels, while side effects such as nausea, vomiting and diarrhoea can influence how much you’re able to eat and drink.

That means dizziness or light-headedness may have a few possible causes. Some of the most common things to consider include:

Low blood sugar

Low blood sugar, also known as hypoglycaemia, can make you feel dizzy or lightheaded. You might also notice symptoms such as sweating, shaking or feeling confused.

This is particularly important to be aware of if you use Mounjaro alongside diabetes medication, as this combination can increase your risk of hypoglycaemia.

If you take medication for diabetes and are experiencing signs of low blood sugar, speak to your healthcare team for support.

Dehydration

Eating less can sometimes mean drinking less too. Even more, if you’re experiencing digestive side effects such as vomiting or diarrhoea, you may be losing additional fluids. If you’re feeling dizzy or lightheaded and notice that you’re thirsty, tired, have a dry mouth, are urinating less often or your urine is dark yellow and strong-smelling, dehydration could be contributing to how you feel. Dehydration is recognised as one potential reason for dizziness during Mounjaro treatment, so make sure to drink plenty of fluids throughout the day.

Nausea and vomiting

Nausea and vomiting are among the common side effects associated with Mounjaro. If vomiting makes it difficult to keep food or fluids down, you may become dehydrated, which, as discussed above, can contribute to feeling dizzy or lightheaded.

Changes in blood pressure

If you feel lightheaded, unsteady or as though you might faint when getting up from a chair or out of bed, it could be related to a temporary drop in blood pressure, also known as postural hypotension. If this keeps happening, speak to your GP, particularly if you take medication for high blood pressure.

How to stop feeling dizzy on Mounjaro

If you’re dizzy on Mounjaro, there are some simple things you can do to help yourself feel steadier. What works best will depend on what’s causing your dizziness, so think about whether you’ve been drinking enough water, when you last ate and, if you monitor them, your blood sugar and blood pressure levels.

Managing dizziness

If you suddenly start feeling dizzy, here are a few simple things that could help:

• Have some water: If you haven’t been drinking enough, topping up your fluids may help. If nausea is making it difficult to drink, try small, regular sips rather than having a large amount at once.
• Sit or lie down somewhere safe: Don’t try to push through a dizzy spell. Sitting or lying down while you wait for it to pass can also help reduce your risk of falling.
• Get up slowly: When you’re ready to move again, take your time. Moving gradually from lying to sitting and then standing can be helpful if your dizziness happens when you change position.
• Check and treat low blood sugar if appropriate: If you have diabetes and experience symptoms of hypoglycaemia, check your blood glucose if you can. The HSE considers a reading below 4 mmol/L to be low. If it is, the HSE recommends having 15g of fast-acting carbohydrates, such as glucose or dextrose sweets or fruit juice, and checking your blood glucose again after 10 minutes. If it remains below 4 mmol/L, repeat the treatment.

Preventing dizziness

While you may not be able to prevent every dizzy spell, a few simple habits can help you reduce some of the things that may contribute to light-headedness:

• Keep your fluids topped up: Try to drink regularly throughout the day, rather than only reaching for water once you feel thirsty. Staying hydrated is especially important if you’re experiencing vomiting or diarrhoea, as both can cause you to lose additional fluid.
• Monitor your blood sugar if you need to: If you have diabetes and your healthcare team has advised you to check your glucose levels, continue doing so as directed. This can help you identify whether low blood sugar could be behind symptoms such as dizziness, sweating, shaking or feeling hungry.
• Keep track of your blood pressure if advised: If you tend to feel lightheaded after standing up, your healthcare team may recommend monitoring your blood pressure. Keep taking any blood pressure medication as prescribed unless a healthcare professional advises you otherwise.
• Ask for support if dizziness continues: You don’t need to simply put up with side effects. If dizziness keeps coming back, isn’t improving or is getting in the way of your everyday life, speak to your myBMI clinician. They can review what you’re experiencing and help you understand the safest next step.

When to seek medical help for dizziness

If your dizziness progresses and becomes unbearable, you should speak to a medical professional. Remember that everybody reacts differently to weight loss medications such as Mounjaro, and some may suffer from side effects more than others.

You should trust your body and seek help when you feel it is needed.

“Dizziness can feel worrying, particularly when you’re not sure why it’s happening. Pay attention to what your body is telling you and take things slowly. If your symptoms persist or concern you, speak to us so we can help you understand what’s happening and support you safely.”

Ayesha BashirPrescribing Pharmacist

What are other side effects of Mounjaro?

Dizziness isn’t the only side effect you might experience while taking Mounjaro. Other common side effects include nausea, diarrhoea, constipation, and vomiting, although everybody’s experience of treatment is different.

For a fuller picture of what you might experience and how to manage it, read our guide to Mounjaro side effects.

Getting support throughout your treatment

Your weight loss journey shouldn’t be something you have to navigate alone. If dizziness or other side effects are making treatment more difficult, reaching out for support can help you understand what you’re experiencing and what to do next.

At myBMI, our IMC-registered doctors are with you throughout your treatment, so you can get advice when you need it and feel supported at every step of the way.

Already a myBMI patient?

Speak to your clinician if you’re experiencing dizziness or any other side effects. They’re there to listen, offer guidance, and help you manage your treatment safely. Additionally, you can request free side effects treatment as part of your next consultation.

Thinking about starting Mounjaro?

Learn more about our Mounjaro treatment plan and the support available throughout your journey.

Sources

• Hypoglycaemia (2024) HSE. [Accessed 5 October 2026]
• Low blood pressure (2021) HSE. [Accessed 5 October 2026]
• Dehydration (2024) HSE. [Accessed 5 October 2026]
• Obesity: medicines (2025) HSE. [Accessed 5 October 2026]
• Diabetes and physical activity (2024) HSE. [Accessed 5 October 2026]