Hot Weather Medication Warning: What People Taking Sertraline, Citalopram, and Fluoxetine Need to Know

New heatwave advice issued for people taking common medicines

As temperatures rise across the UK, people taking certain prescription medicines are being urged to take extra care. Experts have warned that hot weather can affect how some medications work and may increase the risk of dehydration, overheating and other health problems.

Those taking commonly prescribed antidepressants such as sertraline, citalopram and fluoxetine have been advised to be especially aware during periods of extreme heat. These medicines belong to a group called selective serotonin reuptake inhibitors, commonly known as SSRIs.

A pharmacist has explained that while these medicines are safe and effective for many people, they can influence the body’s ability to regulate temperature and recognise signs of dehydration.

With heatwaves becoming more frequent and temperatures reaching uncomfortable levels, understanding how medication and hot weather interact can help people stay safe.

Why can sertraline, citalopram and fluoxetine be affected by heat?

The human body has a natural cooling system that helps maintain a stable temperature. A part of the brain called the hypothalamus plays a major role in controlling temperature, sweating and hydration.

Some antidepressants, including SSRIs such as sertraline, citalopram and fluoxetine, affect serotonin levels in the brain. Serotonin influences many body functions, including mood, sleep and temperature regulation.

During hot weather, some people taking SSRIs may notice changes such as:

• Increased sweating or reduced sweating
• Feeling dizzy or light-headed
• Feeling unusually tired
• Difficulty recognising thirst
• Greater risk of dehydration

Dehydration can happen quickly during hot conditions, especially if someone is spending time outdoors, exercising, drinking alcohol or not consuming enough fluids.

People taking these medicines should not stop their medication because of warm weather. Suddenly stopping antidepressants can cause withdrawal symptoms and may worsen mental health conditions. Instead, anyone experiencing unusual symptoms should speak with a pharmacist or doctor.

Other medicines that may need extra care during hot weather

SSRIs are not the only medicines that may require attention during a heatwave. Many commonly used treatments can interact with high temperatures.

Blood pressure medication

Some blood pressure medicines can affect how the body manages heat and fluid levels.

Diuretics, sometimes called water tablets, increase urine production and can raise the risk of dehydration.

Beta blockers may reduce the body’s ability to increase heart rate in response to heat, which can make it harder to cope with high temperatures.

ACE inhibitors and ARBs can also affect blood pressure regulation, particularly if someone becomes dehydrated.

Anyone taking these medicines should follow medical advice and seek guidance if they experience dizziness, fainting or unusual weakness.

Diabetes medication and insulin

Heat can affect insulin storage and performance. Insulin exposed to high temperatures may become less effective, while heat can also change how quickly insulin is absorbed by the body.

This can increase the risk of blood sugar problems, including hypoglycaemia.

People with diabetes should store insulin according to the instructions provided and avoid leaving medication in hot places such as cars or direct sunlight.

Hormonal contraception

Hormonal contraceptives, including some pills, patches and vaginal rings, may be affected by incorrect storage temperatures.

Medicines containing hormones are usually designed to be stored below certain temperatures. Prolonged exposure to excessive heat may reduce their effectiveness.

People should avoid leaving contraceptive medication in hot cars, handbags exposed to sunlight or warm bathrooms. If there is concern that contraception has been damaged by heat, advice should be obtained from a pharmacist.

ADHD medication and other treatments

Some stimulant medications used for ADHD can increase metabolism and may affect sweating and body temperature.

Other medicines, including certain inhalers, EpiPens and some injectable treatments, can also be damaged if stored incorrectly in high temperatures.

Always check the storage instructions on medication packaging.

How to protect your medicines during a heatwave

Keeping medicines stored correctly is one of the simplest ways to reduce risks during hot weather.

Store medication away from heat

Avoid keeping medicines in places where temperatures can rise quickly, including:

• Cars
• Windowsills in direct sunlight
• Beach bags
• Handbags left outdoors
• Bathrooms with high humidity

A medicine that has changed colour, texture, smell or appearance should be checked with a pharmacist before use.

Drink enough fluids

Staying hydrated is particularly important during hot weather.

Useful tips include:

• Drink water regularly throughout the day
• Do not wait until you feel extremely thirsty
• Limit excessive alcohol consumption
• Be careful with too much caffeine
• Ask a healthcare professional if you have been advised to restrict fluids

Some medicines can affect thirst or fluid balance, meaning people may not notice dehydration developing.

Stay cool during the hottest parts of the day

During heatwaves, try to avoid direct sunlight during the hottest hours, usually between late morning and mid-afternoon.

Helpful steps include:

• Wearing loose, lightweight clothing
• Keeping rooms shaded
• Using fans where appropriate
• Applying high-factor sunscreen
• Taking regular breaks in cooler areas

Some medicines can also make skin more sensitive to sunlight. These include certain antibiotics, retinoid treatments, diuretics and some antidepressants.

Warning signs of heat-related illness

People taking medication during hot weather should be aware of symptoms that may indicate a problem.

Signs of heat exhaustion can include:

• Headache
• Dizziness
• Nausea
• Muscle cramps
• Heavy sweating
• Feeling weak or extremely tired

If someone develops these symptoms, they should move somewhere cooler, drink fluids if able to do so and cool their body with damp cloths or water.

Emergency help should be sought if symptoms become severe. Signs of heat stroke can include confusion, loss of consciousness or the body stopping sweating despite high temperatures.

Heat stroke is a medical emergency and requires urgent treatment.

Do not change medication without medical advice

One of the most important messages for people taking prescription medication is not to make changes without professional guidance.

Stopping antidepressants such as sertraline, citalopram or fluoxetine suddenly can cause unwanted effects. Changing doses of other medicines without advice may also create risks.

If you are worried about how your medication may react during hot weather, speak to a pharmacist, GP or healthcare provider.

Pharmacists can often provide quick advice about storage, side effects and whether further medical support is needed.

Final thoughts

Hot weather can affect everyone, but people taking certain medications may need to take extra precautions. Medicines such as SSRIs, blood pressure treatments, insulin and hormonal contraception can require careful storage and monitoring during heatwaves.

By keeping medicines cool, staying hydrated and recognising warning signs early, many heat-related problems can be avoided.

If you take regular medication and are unsure how high temperatures may affect you, seek advice from a qualified healthcare professional.

Sources

• NHS guidance on medicines, dehydration and heat-related illness: https://www.nhs.uk
• UK Health Security Agency heat-health advice: https://www.gov.uk/government/organisations/uk-health-security-agency
• Met Office heat health information: https://www.metoffice.gov.uk

Disclaimer

This article is for general information purposes only and does not replace professional medical advice. Medication effects can vary between individuals. Do not stop, change or adjust prescribed medicines without speaking to a doctor, pharmacist or another qualified healthcare professional.