Heatwave medication warning: How high temperatures can affect weight-loss jabs, inhalers, insulin and creams… putting YOUR health at risk

The UK is in the midst of its third heatwave of the year, with temperatures consistently rising above 34C.

And while many Britons are focused on avoiding sunburn and staying hydrated, keeping medication at the correct temperature may be just as important.

Health chiefs at the General Pharmaceutical Council say storing medicines at the correct temperature is ‘crucial to maintaining their quality, effectiveness and safety’. 

They advise that medicines that require refrigeration should be kept between 2C and 8C, while most others that are recommended to be kept at room temperature should be stored at temperatures between 15C and 25C.

Once temperatures rise above 25C, some medicines – which people often store in humid areas like cars, kitchens and bathrooms – can become more ineffective. 

If the drugs become too hot their chemical structure may change, meaning creams can separate, liquids may evaporate and capsules can soften or melt.

Speaking earlier this year, Alison Cave, chief medical officer at the Medicines and Healthcare products Regulatory Agency, said: ‘Let’s face it – when there’s a heatwave, most of us are focused on getting outside and enjoying it while it lasts. 

‘But it’s easy to forget that medicines left in the heat – in cars, bags, or on sunny windowsills – might not work properly when you need them.’

Proper storage is important for medicines such as weight–loss injections, which should be stored in the refrigerator. 

Jabs such as Mounjaro and Wegovy can be kept at room temperature for up to 30 days, but during a heatwave they may break down when exposed to excessive heat – reducing their effectiveness. 

This is also the case for insulin, the hormone used to treat diabetes by lowering high blood sugar levels.

The UK Health Security Agency has an amber heat–health alert in place for most of England until 9pm on Sunday, meaning Britain is expected to continue sweltering until the end of the weekend.

Other medicines, including inhalers – used to treat asthma and chronic obstructive pulmonary disease – can also be affected by high temperatures, as the gases inside them can expand in the heat. 

The main ingredient in an inhaler for these conditions is hydrofluoroalkane gas, which helps deliver the medicine into lungs and helps patients with their breathing.

Experts also say that blood glucose monitors, used by people with diabetes to measure blood sugar levels, can become less reliable in hot and humid conditions. 

A 2014 study published in the Journal of Science and Technology found that humidity levels of 83 per cent can contribute to these monitors returning false readings.

Humidity levels inside UK homes can exceed that threshold during the summer. 

In July, indoor humidity can climb above 90 per cent in parts of England, including London and Bournemouth, while cities such as Manchester and Birmingham can also experience levels higher than the study’s threshold.

With research showing that many people store medicines in kitchens and bathrooms, where temperatures and humidity fluctuate, experts are urging the public to keep medicines in cool places and ensure they are stored within their recommended temperature range.

The good news is there are simple steps people can take to protect their medicines during hot weather.

As well as moving medicines away from warm areas and direct sunlight, keeping rooms cool by opening windows during cooler parts of the day and using fans to improve air circulation can help.  

If travelling, which can cause medicines to get hot in pockets and bags, experts say they should be packed in insulated pouches or cool bags – but not placed directly next to ice packs because freezing medicines can also damage them.

Anyone who has concerns about whether their medication has changed as a result of being exposed to excessive heat should seek advice from a healthcare professional.

It is crucial to follow the storage instructions for each medication.