Some medicines can make it harder for your body to cope with very hot weather.
This does not mean that your medicine is unsafe or that you should stop taking it. For most people, no change to their medication will be necessary.
However, if you take one or more of the medicines below, it is worth being particularly careful about keeping cool and avoiding dehydration during very hot weather.
Medicines that may need extra care in hot weather
💧 Water tablets (diuretics)
Examples include furosemide and bumetanide.
These increase the amount of water and salts lost through urine. During hot weather this can increase the risk of dehydration, low blood pressure and changes in body salts.
❤️ Medicines for blood pressure or heart conditions
These include:
ACE inhibitors – such as ramipril and lisinopril
ARBs – such as candesartan and valsartan
Beta-blockers – such as bisoprolol, atenolol and metoprolol
Calcium-channel blockers – such as amlodipine and lercanidipine
Hot weather naturally lowers blood pressure and increases fluid loss. Some of these medicines can therefore increase the likelihood of dizziness, fainting or falls, particularly if you become dehydrated.
🧠 Antidepressants and medicines for mental health
These include some:
Antidepressants – including SSRIs, SNRIs and tricyclic antidepressants
Antipsychotics – such as quetiapine and risperidone
Sedatives and medicines that cause drowsiness
Some can affect sweating, thirst, alertness or the body’s ability to control its temperature.
🚻 Medicines with an anticholinergic effect
These include some medicines used for bladder problems, such as solifenacin and tolterodine, as well as a number of medicines used for other conditions.
They can reduce sweating, making it more difficult for the body to cool itself.
🧠 Medicines for epilepsy
Some anti-seizure medicines, including topiramate, carbamazepine and oxcarbazepine, can affect sweating, fluid balance or how the body responds to heat.
💊 Lithium, digoxin and some other closely monitored medicines
Dehydration can change the amount of some medicines in your bloodstream and increase the possibility of side effects or toxicity.
Lithium is particularly important: if you take lithium, take extra care to avoid dehydration and follow the advice you have been given about fluid intake.
💉 Diabetes medicines
Hot weather and dehydration can affect people with diabetes, and heat can also affect insulin, blood glucose monitors and test strips.
Insulin may be absorbed more quickly in hot weather, potentially increasing the risk of low blood sugar.
💊 Anti-inflammatory painkillers (NSAIDs)
Examples include ibuprofen, naproxen and diclofenac.
If you become significantly dehydrated, these medicines can increase the risk of kidney problems.
☀️ Medicines that can make your skin more sensitive to sunlight
Some medicines can make you burn more easily or cause a skin reaction in strong sunlight. Examples include some antibiotics such as doxycycline and ciprofloxacin, some antifungal medicines and methotrexate.
Check the information supplied with your medicine and take particular care with shade, protective clothing and sunscreen.
What should I do?
Keep taking your medicines as prescribed. Do not stop, reduce or alter a medicine because the weather is hot unless a healthcare professional has advised you to do so.
During very hot weather:
- keep yourself as cool as possible
- drink regularly, unless you have been specifically advised to restrict your fluid intake
- avoid becoming dehydrated
- get up slowly if you are prone to dizziness
- protect yourself from strong sunlight
- keep medicines cool, dry and away from direct sunlight, following the storage instructions on the packaging.
Not sure about one of your medicines?
Ask your local pharmacist.
Pharmacists are medicines specialists and can check your individual medicines and tell you whether you need to take any additional precautions during hot weather.
You do not normally need an appointment with your GP or hospital specialist simply because your medicine appears on this list.
If your pharmacist believes that your medication needs reviewing, they can advise you about the appropriate next step.
When to seek medical help
If you become unusually dizzy, faint, confused, very weak, develop significantly reduced urine output, or are concerned that you may be dehydrated or suffering from heat-related illness, seek medical advice.
Heatstroke is a medical emergency. If someone is very hot and becomes confused, has a seizure, loses consciousness or is otherwise seriously unwell, call 999.
This is general information to help you stay safe during hot weather. It is not a complete list of medicines that may be affected by heat, and individual circumstances vary. Never stop or change prescribed medication without appropriate professional advice.