Medication and extreme heat

Some medicines can affect the way your body reacts to heat.

Why is it important to be careful?

Some treatments can:

• Disrupt the body’s ability to regulate its temperature
• Increase dehydration
• Affect the effectiveness and tolerability of medicines

As a result: there is an increased risk of feeling unwell, severe fatigue or complications, especially among older people or people taking several medicines.

What about the sun?

Some medicines can also cause skin reactions when exposed to sunlight (redness, burns, irritation, sometimes severe).

Examples of the main situations at risk

Medicines that can worsen dehydration

> They increase fluid loss or reduce the sensation of thirst.

Examples:

• Diuretics
• Laxatives
• Certain antihypertensive medicines

Medicines that affect body temperature regulation

> They prevent the body from cooling down properly.

Examples:

• Anticholinergic medicines
• Antipsychotics (neuroleptics)
• Antidepressants
• Sedating antihistamines

Medicines whose effects may be altered by heat

> Risk of overdose or reduced effectiveness.

Examples:

• Insulin (increased sensitivity to variations)
• Cardiovascular medicines
• Certain long-term treatments affected by dehydration

Medicines that increase the risk of photosensitivity

> Skin reactions that can sometimes be severe.

Examples:

• Antibiotics (e.g. tetracyclines)
• NSAIDs (including topical ketoprofen)
• Certain antidepressants

> Ketoprofen gel is associated with a particularly high risk, with potentially serious skin reactions, even after indirect exposure to sunlight.