Medications and Heat: Storing Them Correctly and Staying Safe Through Summer

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

1. Two dangers: heat and medications

When it comes to medications and heat, there are two quite different dangers that should be kept apart:^¹

• Heat alters the medication: high temperatures can break down 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 to heat (e.g. a higher risk of dehydration or heat stroke)

Both aspects are important and are covered in this guide. Especially with increasingly hot summers and for people who take medications long-term, it's worth knowing both dangers — and preventing them with simple measures.

2. How heat alters medications

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

• Breakdown of the active ingredient: some active ingredients break down faster in the heat and lose effect
• Altered 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 products (e.g. insulin, certain injections): especially sensitive, since protein structures can be destroyed by heat (and frost)
• Visible signs: discoloration, changed consistency, clumping — don't use such medications anymore

The tricky part: a heat-damaged medication often looks unchanged but has lost effect. This 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 may 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/biological products — very sensitive to heat (and frost) (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) — don't expose to great heat or direct sun
• Liquid medications, syrups, eye drops — often sensitive, some to be stored refrigerated once opened
• Certain patches (e.g. medicated patches) — heat can change the release of the active ingredient

For all of them: follow 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 apartments, cars and at the beach — so particular caution is needed here.

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)
• Insulin in use is usually good at room temperature (below 25–30 °C) for a few weeks — but protect it from heat
• Don't leave it in a hot car, at the beach or in direct sun — high temperatures destroy the protein structure and make the insulin ineffective
• When traveling: use a cool bag (with an ice pack, but don't place the insulin directly on the pack — risk of freezing); in your hand luggage, not in the hold
• Visual check: don't use discolored, flaky or clumpy insulin anymore

5. Thyroid hormones and other sensitive products

Other frequently used medications are sensitive too:

Thyroid hormones (levothyroxine)

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

Other sensitive products

• Suppositories: store in the fridge when it's hot — otherwise they melt
• Asthma sprays and other pressurized gas canisters: protect from heat and direct sun
• Liquid antibiotics and syrups: often to be stored cool once opened
• Eye drops: some require refrigeration, follow 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 notes in summer and choose a cool, dry, dark place to keep them — not the bathroom (humid) and not the sunny windowsill.

6. Which medications increase the heat risk

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

• Diuretics (water tablets): increase fluid loss — in the heat (extra sweating), risk of dehydration and electrolyte disturbances
• Blood pressure-lowering medications: in the heat the blood vessels widen anyway — together with blood pressure medications, blood pressure can drop too much (dizziness, risk of falls)
• Certain psychotropic medications (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 and other agents
• Medications that strain the kidneys (e.g. NSAIDs, especially in combination with diuretics and blood pressure medications) — an additional risk when fluid is lacking

7. Heat, fluids and electrolytes

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

• Drink enough: more than usual in the heat — water, unsweetened teas; pay attention to your own needs and medical instructions
• Caution with fluid restrictions: people with heart or kidney disease sometimes have a doctor-prescribed fluid limit — here, clarify with a 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 the kidneys: on certain blood pressure medications (e.g. valsartan, ACE inhibitors) plus a lack of fluid, kidney function can worsen

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 a doctor, especially with heart, kidney and blood pressure conditions.

8. Recognizing heat stroke and heat exhaustion

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

Heat exhaustion (the precursor)

Signs: heavy sweating, weakness, dizziness, headache, nausea, a fast pulse, paleness. What to do: go to a cool place, lie down, raise the legs, drink, cool down. If it doesn't improve or gets worse, seek medical help.

Heat stroke (emergency)

With heat stroke, temperature regulation fails — a life-threatening emergency. Signs: 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. Those who know the warning signs can take countermeasures early.

9. Correct storage at home and on the go

Here's how to store medications correctly in the heat:

• Cool, dry, dark — a cupboard in a cool room is ideal. NOT the humid bathroom and NOT the sunny windowsill.
• Follow the manufacturer's instructions: "below 25 °C", "below 30 °C" or "in the fridge" — it's in the package leaflet.
• The fridge for refrigerated products — but don't freeze them (e.g. insulin).
• Never leave them in the car: in summer a car heats up to extremes very quickly — even a short time is enough for damage.
• On the go: a cool bag for sensitive/refrigerated medications; don't leave medications lying in direct sun (e.g. at the beach).
• The original packaging with the leaflet (storage notes, shelf life).
• Check the shelf life and sort out visibly changed medications (discoloration, melting, clumping).

More on transport when traveling (airplane, cool bag, certificates) can be found in the guide Travel First-Aid Kit. When in doubt, the pharmacy can help with the question of whether a heat-exposed medication may still be used.

10. Tips for hot days while on medication

Anyone who takes medications long-term can get through heat waves more safely with these tips:

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

When unsure — for example whether the fluid amount or the medication dose should be adjusted during a heat wave — consulting a doctor is the right way. This caution is especially worthwhile with heart, kidney and blood pressure conditions and with diabetes.

11. People who are especially at risk

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

• Older people: 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 bedbound people

For these groups, prevention is especially important: drink enough (within the medical instructions), a cool environment, knowing the warning signs and seeking medical help earlier when in doubt. During heat waves, relatives should actively help and ask whether the medication should be reviewed during prolonged 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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