Medications and heat: storing them correctly and staying safe through the summer

Summer heat is a strain not only on the body but also on medications. High temperatures can change active ingredients and make them ineffective — and conversely, some medications increase the body's sensitivity to heat. Both are often underestimated.

1. Two dangers: heat and medications

With the topic of medications and heat there are two quite different dangers that should be kept apart:^¹

• Heat changes the medication: high temperatures can decompose active ingredients, weaken their effect or change their properties — the medication becomes ineffective or unsafe
• The medication increases the body's heat risk: some medications affect temperature regulation, the fluid balance or circulation — and make the body more sensitive in the heat (e.g. a higher risk of dehydration or heatstroke)

Both aspects are important and are covered in this guide. Especially with increasingly hot summers and in people who take medications permanently, it is worth knowing both dangers — and preventing them with simple measures.

2. How heat changes medications

Medications are designed for certain storage conditions — usually room temperature, often below 25 °C. Excessive heat can impair them in various ways:^¹

• Active-ingredient decomposition: some active ingredients break down faster in the heat and lose effect
• Changed release: with certain tablets/capsules (e.g. with a special coating) the release of the active ingredient can be disrupted
• Physical changes: suppositories melt, creams/ointments can separate, sprays/pressurized gas canisters can become dangerous in great heat
• Biological preparations (e.g. insulin, certain injections): especially sensitive, because protein structures can be destroyed by heat (and frost)
• Visible signs: discoloration, changed consistency, clumping — do not use such medications any more

The tricky thing: a heat-damaged medication often looks unchanged, but has lost effect. That can become dangerous — for example when a vital medication (e.g. insulin) no longer works properly. When in doubt, ask at the pharmacy whether a medication can still be used after heat exposure.

3. Especially heat-sensitive medications

Some medications react especially sensitively to heat. These include above all:

• Insulin and other injectable protein/biologic preparations — very heat- (and frost-)sensitive (its own chapter)
• Thyroid hormones (levothyroxine) — sensitive; store cool and dry
• Suppositories — melt in the heat
• Creams, ointments, gels — can separate in the heat
• Sprays and pressurized gas canisters (e.g. asthma sprays) — do not expose to great heat or direct sun
• Liquid medications, syrups, eye drops — often sensitive, some to be kept refrigerated after opening
• Certain patches (e.g. active-ingredient patches) — heat can change the release of the active ingredient

For all of them: observe the storage information in the package leaflet. Many medications are to be stored "below 25 °C" or "below 30 °C", some in the fridge. In high summer it can get considerably hotter in homes, cars and on the beach — here special caution is needed.

4. Storing insulin correctly in the heat

Insulin is a prime example of a heat-sensitive, vital medication — and an important topic in summer for many people with diabetes:

• Store the supply in the fridge (usually 2–8 °C) — but do NOT freeze it (frozen insulin is unusable)
• Opened insulin usually keeps at room temperature (below 25–30 °C) for a few weeks — but protect it from heat
• Do not leave it in a hot car, on the beach or in the blazing sun — high temperatures destroy the protein structure and make the insulin ineffective
• When travelling: use a cool bag (with an ice pack, but do not put the insulin directly on the pack — risk of freezing); in your hand luggage, not in the cargo hold
• Visual check: do not use discoloured, flaky or lumpy insulin any more

5. Thyroid hormones and other sensitive medications

Other commonly used medications are also sensitive:

Thyroid hormones (levothyroxine)

Levothyroxine (the thyroid hormone for hypothyroidism) is sensitive to heat and moisture. It should be stored cool and dry (observe the manufacturer's instructions) — not in the warm, damp bathroom and not in the blazing sun. A loss of effect would impair the thyroid setting.

Other sensitive medications

• Suppositories: store in the fridge when it is hot — otherwise they melt
• Asthma sprays and other pressurized gas canisters: protect from heat and direct sun
• Liquid antibiotics and syrups: often to be kept cool after opening
• Eye drops: some need refrigeration, observe the manufacturer's instructions
• Certain patches and gels: heat can change the release of the active ingredient

In general: anyone who takes medications regularly should briefly check the storage instructions in summer and choose a cool, dry, dark storage place — not the bathroom (damp) and not the sunny windowsill.

6. Which medications increase the heat risk

The second, often underestimated danger: some medications affect how the body deals with heat — they can impair temperature regulation, the fluid balance or circulation. During heatwaves, this increases the risk of circulatory problems, dehydration and heatstroke:^¹

• Diuretics: increase fluid loss — in the heat (extra sweating) a risk of dehydration and electrolyte disturbances
• Blood-pressure-lowering medications: in the heat the vessels widen anyway — together with blood-pressure medications, blood pressure can drop too much (dizziness, risk of falling)
• Certain psychotropic drugs (e.g. some antidepressants, antipsychotics): can affect temperature regulation and sweating
• Anticholinergic medications: can reduce sweating — the body cools less well
• Certain Parkinson's and thyroid medications as well as other agents
• Medications that strain the kidneys (e.g. NSAIDs, especially in combination with diuretics and blood-pressure medications) — an additional risk with fluid deficiency

7. Heat, fluid and electrolytes

In the heat, the body loses a lot of fluid and salts (electrolytes) through sweating. That is a strain in itself — but on certain medications it becomes especially relevant:

• Drink enough: in the heat more than usual — water, unsweetened teas; pay attention to your own needs and medical instructions
• Caution with a fluid restriction: people with heart or kidney disease sometimes have a doctor-prescribed fluid amount — here, clarify with the doctor how much to drink in the heat
• Electrolytes: with heavy sweating, salts are also lost; pay attention to a balanced diet, get medical advice if needed
• Diuretics and heat: the combination can lead to fluid and salt deficiency especially quickly — watch for warning signs
• Potassium and kidney: on certain blood-pressure medications (e.g. valsartan, ACE inhibitors) plus fluid deficiency, kidney function can deteriorate

The right amount to drink in the heat is individual — most people should drink more, but some (e.g. with heart failure and a fluid restriction) have to be careful. When in doubt, clarify with the doctor, especially with heart, kidney and blood-pressure conditions.

8. Recognizing heatstroke and heat exhaustion

In great heat — especially on risk medications — the body can overheat. It is important to know the warning signs:

Heat exhaustion (early stage)

Signs: heavy sweating, weakness, dizziness, headache, nausea, a fast pulse, paleness. Measures: go to a cool place, lie down, raise the legs, drink, cool down. If this does not improve or gets worse, get medical help.

Heatstroke (emergency)

With heatstroke, temperature regulation fails — a life-threatening emergency. Signs: a very high body temperature, hot/dry or also sweaty skin, confusion, impaired consciousness, seizures.

People on risk medications, older people and the chronically ill are especially at risk. Anyone who knows the warning signs can counteract early.

9. Correct storage in everyday life and on the go

This is how you store medications correctly in the heat:

• Cool, dry, dark — a cupboard in a cool room is ideal. NOT the damp bathroom and NOT the sunny windowsill.
• Observe the manufacturer's instructions: "below 25 °C", "below 30 °C" or "in the fridge" — it is in the package leaflet.
• The fridge for medications needing refrigeration — but do not freeze them (e.g. insulin).
• Never leave them in the car: in summer the car heats up extremely quickly — even a short time is enough for damage.
• On the go: a cool bag for sensitive/refrigeration-needing medications; do not leave medications in the blazing sun (e.g. on the beach).
• The original packaging with the package leaflet (storage instructions, shelf life).
• Check the shelf life and sort out visibly changed medications (discoloration, melting, clumping).

You can find more on transport when travelling (plane, cool bag, certificates) in the guide travel first-aid kit. When in doubt, the pharmacy can help with the question of whether a heat-exposed medication can still be used.

10. Tips for hot days while on medication

Anyone who takes medications permanently can get through heatwaves more safely with these tips:

• Drink enough (provided there is no medical fluid restriction)
• Avoid heat: avoid the midday heat, stay in the shade/cool rooms, put physical exertion into the cooler times of day
• Light, light-coloured, airy clothing and a head covering
• Watch for warning signs: dizziness, weakness, confusion, very dark/little urine (dehydration)
• Do not stop or change medications on your own — ask the doctor if you have concerns
• Keep an eye on blood pressure/blood sugar — heat can change the values
• Store medications cool and check for visible changes before taking them
• Look out for others: support older or dependent relatives in the heat

If you are unsure — for example whether the amount to drink or the medication dose should be adjusted during a heatwave — consulting the doctor is the right way. Especially with heart, kidney and blood-pressure conditions and with diabetes, this caution is worthwhile.

11. Especially vulnerable people

Some groups are especially at risk in the heat — above all on medication — and need special attention:

• Older people: a reduced sense of thirst, often several medications (diuretics, blood-pressure-lowering medications), poorer temperature regulation
• People with cardiovascular diseases (e.g. heart failure, high blood pressure)
• People with kidney diseases
• People with diabetes (insulin storage, blood-sugar fluctuations)
• People with certain psychiatric or neurological conditions and the corresponding medications
• Small children and infants (overheat quickly)
• People in need of care and bedridden people

For these groups, prevention is especially important: drink enough (within the medical instructions), a cool environment, know the warning signs and, when in doubt, get medical help earlier. Relatives should actively support during heatwaves and ask whether the medication should be reviewed during persistent heat.

12. How brite helps you in the heat

On hot days, several things matter at once: correct storage, consistent intake despite the heat, an eye on values and interactions. brite bundles that:

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