Why it quickly becomes too little
- Thirst is often dampened on GLP-1 medications
- If you eat less, you take in less water from food
- Nausea, vomiting or diarrhoea cost additional fluid
- Blood pressure medications or diuretics make dizziness worse when you are short of fluids
How much makes sense?
The German Nutrition Society (DGE) gives around 1.5 litres of drinks per day as a guideline for adults – correspondingly more in heat, with exercise, diarrhoea or vomiting. On GLP-1 medications many people deliberately plan a little more, because less water comes in through food. A practical test: if your urine is pale yellow, you are usually fine.
Several litres beyond your normal needs bring no extra benefit. Very large amounts in a short time can lower your sodium level dangerously. If you have heart or kidney disease, always discuss how much to drink with your doctor.
Tips to make it work
- Fixed times to drink: after getting up, with every meal, in the afternoon
- Keep a bottle where you can see it
- Herbal tea, water with lemon or cucumber – variety helps
- With diarrhoea or in hot weather, think of electrolytes (pharmacy)
When to see a doctor
- Dizziness when standing up, a racing heart or very little urine
- Confusion, severe headaches or seizures after drinking a very large amount
- Persistent diarrhoea or vomiting
In an emergency: call 112.
FAQ
How much should I drink on Mounjaro?
The guideline is around 1.5 litres of drinks per day, more in heat, with exercise or with stomach and bowel problems. Pale urine is a good indicator.
Why do I feel dizzy on the weight-loss injection?
Common reasons are too little fluid, too little food or low blood pressure, especially if you take blood pressure medication. If you take diabetes medication, also consider low blood sugar.
Is 5 litres of water a day good?
For most people that is considerably more than necessary. Very large amounts in a short time can lower your sodium level dangerously.
This article does not replace medical advice. It does not give any dosing recommendations. As of September 2026.