It’s rare, but Mounjaro can cause low blood sugar or hypoglycaemia, especially if you’re already taking medication for it. And, while having a ‘hypo’ (blood glucose levels dropping below 4mmmol/L) is uncommon, it is very treatable.
Here, we take a look at what hypoglycaemia is, how it’s affected by Mounjaro, and what to look out for to make sure you’re safe and informed.
What is hypoglycaemia?
Hypoglycaemia means that the sugar levels in your blood have dropped much lower than usual and are below the standard range.
The level of sugar (glucose) in your blood varies throughout the day and changes according to what you’ve eaten or how active you are.
If your blood sugars dip too low, you might feel dizzy and ill. This is unpleasant, but it is manageable by boosting your blood sugar levels.
What is classed as low blood sugar?
You are considered to have low blood sugar if your blood glucose level is below
4 millimoles per litre (mmol/L) (or 70 milligrams per decilitre, mg/dL). Mmol/L is the standard measurement for blood sugar in the UK.
You might use a blood sugar monitor to check your glucose levels. Some models use finger-prick tests, while others are continuous glucose monitors (CGMs) worn on your body.
You’ll usually be able to feel that you have low blood sugar; your body will alert you with signs and symptoms, like feeling hungry, dizzy, shaky, or cold.
Can Mounjaro cause low blood sugar if I’m not diabetic?
Studies have shown that very few of those (only 1-3%) taking Mounjaro purely as a weight-loss drug will experience hypoglycaemia, or very low blood sugar levels. So, while it technically can happen, it’s not very likely.
Your prescriber will be able to tell you more about what to expect when taking Mounjaro.
What are low blood sugar symptoms?
The symptoms of low blood sugar (hypoglycaemia) can include:
- hunger
- shaking
- sweating
- irritability
- anxiety
- faster heartbeat
- weakness
- confusion
- blurred vision
- tingling lips or fingers
Very low blood sugar symptoms can include:
- seizures
- fits
- extreme sleepiness
- becoming unconscious
What to eat when blood sugar is low
Eating 15-20 grams of fast-acting carbohydrates (high-sugar food) can quickly help to raise your glucose levels. You should feel better within minutes.
Fast-acting carbohydrates include:
- honey.
- glucose tablets.
- sugar.
- sweets (jelly babies work very well).
- sugary drinks.
- fruit juice.
- glucose drinks such as Lift.
- dates.
Avoid foods high in fat, like chocolate, cakes, or biscuits, as fat slows the rate at which sugars are absorbed into the bloodstream. Foods as close as possible to raw sugar or glucose work fastest.
If you continue to experience symptoms after 15 minutes or a blood test shows that your levels are still below 4mmol/L, have another sugary drink or sweet snack.
Once your levels are stable, eat a slower-acting carb that will keep your levels at an acceptable level. Your choices might include
- biscuits.
- toast.
- pasta.
- bananas.
If someone has very low blood sugar and has lost consciousness or is having a fit or seizure, do not give them food and seek urgent medical attention.
If your blood sugar regularly drops to low levels, speak to your prescriber. You may need to adjust your treatment.
How to avoid low blood sugar when taking Mounjaro
To reduce regular hypos or episodes of low blood glucose levels:
- follow your treatment plan carefully
- speak to your prescriber about your dosage
- carry treatments with you
- stick to regular meal times
- monitor blood sugar levels to get to know your patterns and help you recognise signs of low blood sugar
- avoid drinking alcohol without eating
- manage your stress levels
- if exercise regularly causes low blood sugar levels, eat a snack before you hit the track!
Overview of dealing with low blood sugar from Mounjaro:
| Symptoms | Blood sugar level | What to eat / do |
| Hunger, dizziness, shaking, sweating, irritability, anxiety, fast heartbeat, weakness, confusion, blurred vision, tingling lips or fingers | Below 4 mmol/L (mild to moderate) | Quick-acting sugar: honey, glucose tablets, sugar, jelly babies, boiled sweets, sugary drinks, fruit juice, or glucose drinks (e.g. Lift). |
| Seizures, fits, extreme sleepiness, unconsciousness | Below 4 mmol/L (severe) | Seek immediate medical help. |
| Hunger, dizziness, shaking, sweating, irritability, anxiety, fast heartbeat, weakness, confusion, blurred vision, tingling lips or fingers | Above 4 mmol/L (after initial treatment) | Slow-release carbs to keep blood sugar stable: biscuits, toast, pasta, bananas. |
Sources
- Tirzepatide versus insulin glargine in type 2 diabetes and increased cardiovascular risk (SURPASS-4): a randomised, open-label, parallel-group, multicentre, phase 3 trial . The lancet. [Accessed 10th October 2025]
- Low blood sugar (hypoglycaemia). NHS. [Accessed 10th October 2025]
- Low Blood Glucose (Hypoglycemia) National Institute of Diabetes and Digestive and Kidney Disease. [Accessed 10th October 2025]
- Mounjaro patient information leaflet. [Accessed 10th October 2025]
