When heatwaves strike, it’s not just a matter of protecting your health from the heat: medicines can also be sensitive to high temperatures. Incorrect storage can alter the properties of a medicine and, in some cases, compromise its effectiveness and safety.
Knowing how to store medicines in summer, how to transport them while travelling and what to do if they have been left in a hot car is therefore important, especially for those on long-term treatment or using medicines that are particularly sensitive to temperature changes.
The guidelines from the Italian Medicines Agency (AIFA) and Italy’s Ministry of Health recommend always checking the patient information leaflet and following the specific storage temperature indicated for each medicine.
Medicines and heat: why can high temperatures be a problem?
Heat, direct exposure to the sun, humidity and sudden changes in temperature can affect the stability of certain medicines.
Not all medicines react in the same way: some are more sensitive to temperature, others to light or humidity. Even the dosage form can make a difference. In general, liquid formulations may be more sensitive to high temperatures than solid ones.
For this reason, there is no single temperature at which ‘all medicines become unusable’. It all depends on the specific medicine. Unless otherwise specified, AIFA recommends storing medicines in a cool, dry place, generally below 25 °C. In any case, the specific instructions provided in the patient information leaflet should be followed. ‘Some medicines have specific requirements and must be stored within very precise temperature ranges,’ says Professor Giovanna Petrucci, lecturer in Pharmacology at UniCamillus University. ‘It is incorrect to assume that medicines can be stored at any summer temperature without distinction. In the event of accidental exposure to heat, especially if prolonged, it is best not to make decisions on your own: you should check the product information leaflet and, if there are any doubts about the integrity of the medicine, seek advice from a pharmacist or a medical professional”.
How to store medicines in summer?
Following a few simple rules will help ensure medicines are stored correctly in hot weather:
- always check the temperature specified in the patient information leaflet;
- store medicines in a cool, dry place, away from sources of heat;
- avoid direct exposure to sunlight;
- keep medicines in their original packaging;
- avoid very damp environments, such as the bathroom;
- do not leave medicines in the car for long periods;
- do not mix different medicines in the same container;
- check the appearance of the medicine before use.
The Ministry of Health also emphasises the importance of the original packaging, which ensures that information such as the batch number, expiry date and package leaflet is always available.
Please note: not all medicines need to be kept in the fridge. “The fridge is not always the best way to protect medicines from heat. It should only be used when the packaging or patient information leaflet specifies that the medicine must be stored in the fridge or at a controlled temperature”, continues Professor Petrucci.
Heat-sensitive medicines: which ones are most sensitive to heat?
The term ‘heat-sensitive medicines’ refers to medicines that are particularly sensitive to temperature fluctuations and require specific storage conditions.
Depending on the product, the medicines and categories for which particular care is required include:
- insulin;
- certain antibiotics;
- certain biologics;
- medicines requiring refrigeration;
- certain hormonal products;
- certain liquid formulations;
- certain medicines in spray or pressurised containers.
However, it is not possible to determine heat sensitivity just from the category: the specific storage instructions provided in the patient information leaflet should always be followed.
You should also keep an eye on diagnostic test strips. “Test strips for certain diagnostic tests, such as those used to measure blood glucose levels, are not medicines but can be sensitive to temperature and humidity,” continues Petrucci. “It is therefore important to store them in accordance with the instructions provided by the pharmaceutical manufacturer, as inappropriate conditions can compromise the reliability of the result”.
Insulin and heat: how should it be stored?
Insulin is one of the medicines for which the storage temperature must be monitored with particular care.
“For insulins that require refrigeration, the AIFA guidelines provided with individual products generally specify a range of 2–8 °C,” emphasises Petrucci. “When travelling, it is advisable to use a transport system that allows the specified temperature to be maintained, whilst ensuring the product does not freeze.”
Thyroid medicines and heat
Some thyroid medicines and other hormone-based medicines may be sensitive to temperature changes. AIFA recommends storing them in a cool place at a constant temperature, always following the specific instructions given in the patient information leaflet.
The contraceptive pill in hot weather: can heat damage it?
Oral contraceptives must also be stored in accordance with the specific product instructions. Excessive heat can be a problem if the medicine is stored in conditions other than those specified. For this reason, it is important to avoid leaving the pack in direct sunlight, in a car or in other places where temperatures can rise very high.
Anticoagulants and high temperatures
Anticoagulants require special care during the summer, particularly when they form part of long-term treatment. “Storage conditions can vary between different medicines and, as with all other medicines, it is therefore important to follow the instructions in the patient information leaflet and avoid leaving packs in the car or exposed to direct sunlight”, warns the lecturer.
“Heat can also lead to dehydration and fluctuations in blood pressure, increasing the risk of complications in some people”, the expert continues. “This does not, however, mean that you should stop or alter your anticoagulant treatment on your own. If you have any doubts about how to store the medicine or about your treatment during the hottest days, please ask your physician or pharmacist”.
Suppositories, vaginal suppositories, creams and ointments: what happens in hot weather?
High temperatures can more easily alter the appearance of certain pharmaceutical products.
Suppositories and vaginal suppositories may soften or lose their shape; creams and ointments may change consistency. Syrups and drops may also be more sensitive to environmental conditions than solid formulations.
However, a change in appearance alone does not indicate whether the medicine is still safe.
The Ministry of Health lists changes in colour, consistency, smell or other characteristics of the product as possible signs of deterioration.
How to transport medicines when travelling in summer
Before setting off, it is advisable to put together a small travel first-aid kit, keeping the medicines in their original packaging.
For medicines that require a controlled temperature, it may be necessary to use a cool bag for medicines, following the specific instructions for the product and the medicine.
“It is important, however, to avoid direct contact between the medicine and cooling elements where this could cause it to freeze”, emphasises Professor Petrucci.
Medicines in the car in summer: where to store them?
Cars can reach very high temperatures in summer, especially when parked in the sun. For this reason, medicines should not be left for hours in the passenger compartment or in the boot.
AIFA recommends avoiding exposure to the sun whilst travelling and using insulated containers where necessary. In particular, the boot can be hotter than the passenger compartment.
The best solution is to plan your journey so as to avoid leaving the medicine in the car for any longer than necessary.
How should you carry medicines on a plane?
Essential medicines, particularly life-saving ones, should be carried in your hand luggage, together with your prescriptions where necessary.
AIFA and Italy’s Ministry of Health also recommend not leaving medicines in checked-in luggage if they might be needed during the journey.
For liquid medicines, it is also important to check the rules applicable to carrying liquids in the cabin and any procedures required by the airport or the airline.
High temperatures and medicines: how heat can affect the efficacy of certain medicines
During a heatwave, attention should not be focused only on how to store medicines: high temperatures can also affect the way the body reacts to certain medicines. Heat promotes vasodilation, sweating and the loss of fluids and salts, which in some cases can alter the effects of treatment. Consequently, certain medicines may have a more profound effect on blood pressure or fluid balance, increasing the risk of hypotension, dizziness, weakness and dehydration.
“This applies in particular to certain types of antihypertensives and diuretics, but other medicines may also require caution on very hot days,’ explains the expert. You should also be careful with certain diabetes medicines, particularly those that promote the excretion of sugar and water in the urine, as they can increase the risk of dehydration. Lithium, used to treat certain psychiatric conditions, can also reach excessively high concentrations in the blood in the event of dehydration, increasing the risk of toxic effects”.
Some medicines can also reduce sweating, making it harder for the body to dissipate heat and increasing the risk of overheating. This is the case with certain medicines used, for example, to treat gastrointestinal, urinary or neurological problems.
The risk may be higher in older people, in those with chronic conditions or in those taking several medicines at the same time.
Medicines and the sun: be aware of photosensitisation
Some medicines can increase the skin’s sensitivity to sunlight and cause photosensitisation reactions, such as redness, dermatitis or other skin reactions.
The categories listed by Italy’s Ministry of Health include, amongst others, certain antibiotics, sulphonamides, NSAIDs, oral contraceptives and other medicines.
Particular attention should also be paid to ketoprofen-based products for topical use, for which the patient information leaflet may include specific precautions regarding sun exposure.
If you are taking medication during the summer, it is therefore important to read the warnings regarding sun exposure and seek advice from your doctor or pharmacist if in doubt.
7 mistakes to avoid when storing medicines in summer
To protect your medicines during heatwaves, be sure to avoid these mistakes in particular:
- Leaving medicines in the car for long periods.
- Exposing them to direct sunlight, even for several hours.
- Putting all medicines in the fridge without checking the instructions.
- Transferring tablets to unsuitable containers, thereby losing the original packaging and important information.
- Storing medicines in the bathroom, where humidity and temperature can be high.
- Using a medicine that looks altered without seeking professional advice.
- Stopping or changing a course of treatment simply because it is very hot.
The last point is particularly important: heat can affect certain treatments, but any changes must be discussed with your doctor.