Medicines and extreme heat: what to check in summer
Let's be clear. When a heatwave arrives, many people immediately think of water, shade, or sun protection. But there's another very common question that sometimes goes unnoticed: can heat affect medicines?
The relationship between medicines and extreme heat
Not everything related to medicines and summer means the same thing.
On one hand, there's storage. Some medicines need to be kept between 2 and 8 °C, others should be stored below 25 or 30 °C, and some do not require special conditions. These instructions should always be checked in the patient information leaflet and on the packaging.
On the other hand, there's the effect of heat on the person taking the treatment. The AEMPS warns that, during a heatwave, certain medicines can worsen dehydration, affect kidney function, alter thermoregulation, or complicate heat exhaustion or heatstroke.
How to store medicines when temperatures rise sharply
The first rule remains the most useful: read the patient information leaflet. This is where the actual storage conditions are listed. The AEMPS insists on this point and reminds us that if a medicine requires a special temperature, that information also appears on the packaging.
At home, it's sensible to store them in a cool, dry place protected from heat. And during travel, it's advisable to avoid the car in the sun, as the AEMPS advises against leaving medicines in car boots or cabins exposed to very high temperatures.
When the medicine needs refrigeration
Here, stricter rules apply. Medicines that must be kept between 2 and 8 °C need to be stored in the fridge. And, if transported, the General Council recommends using a portable cooler until reaching home.
This is especially relevant for some injectable treatments, certain diabetes medications, and vaccines, which require more careful maintenance of the cold chain.
What signs might indicate that a medicine has been altered
Some pharmaceutical forms are more sensitive to heat. The AEMPS and the General Council specifically highlight creams, ointments, gels, ovules, and suppositories. If their appearance changes, if phases separate, if they soften or no longer look normal, they should not be used without prior consultation.
Which treatments might require more attention during a heatwave
In addition to storage, some treatments can make the body cope worse with a heatwave.
The AEMPS groups several scenarios here: medicines that promote hydration or electrolyte imbalances, treatments that can affect kidney function, drugs whose behaviour changes with dehydration, and others that alter thermoregulation.
Among the groups most frequently mentioned in official recommendations are diuretics, non-steroidal anti-inflammatory drugs, some antihistamines and drugs with anticholinergic effects, and some neurological or psychiatric treatments.
Who should take extra precautions in summer
Not everyone has the same risk. The AEMPS highlights elderly people, children, people with chronic conditions requiring medication, and dependent individuals as particularly vulnerable groups.
Therefore, for someone taking multiple medicines, with a history of cardiovascular issues, diabetes, kidney disease, or mobility problems, it makes even more sense to review their usual medication before a trip or a period of intense heat.
What to do if you have doubts
The most sensible approach is not to improvise, but to check four things: examine the patient information leaflet and packaging, confirm if it needs refrigeration or specific temperature limits, observe if the medicine's appearance has changed, and consult your pharmacist or doctor if you take several treatments or have been exposed to intense heat.
You may also be interested in reading about travel medicine kits and paracetamol.
