As temperatures rise, it’s important to be aware that some medicines can affect how the body regulates temperature and loses heat. This can increase the risk of dehydration or overheating, particularly during periods of hot weather.
This is especially important for people taking medication for mental health conditions. Medicines that may increase the risk include:
- Antipsychotic medications
- Lithium
- Some antidepressants
- Certain antihistamines
- Anticholinergic medicines
If you take lithium
If you are prescribed lithium, it is particularly important to stay well hydrated and drink fluids regularly during hot weather. Dehydration can affect lithium levels in the body and may increase the risk of side effects.
What you can do
To help stay safe during hot weather:
- Drink plenty of fluids throughout the day
- Stay in the shade or cool indoor spaces where possible
- Avoid spending long periods in direct sunlight
- Keep your home and workplace cool
- Look out for signs of dehydration, such as feeling thirsty, dizzy or having dark-coloured urine
When to seek advice
If you have any concerns about how hot weather may affect your medication, please contact your clinician or healthcare professional for advice and support.
Do not stop taking prescribed medication without first speaking to the healthcare professional responsible for your care.
For more information on staying safe in hot weather, visit the https://www.nhs.uk/live-well/seasonal-health/heatwave-how-to-cope-in-hot-weather/.
Published: 25 June 2026
