MHRA says some medicines increase sun and heat risk
When we talk about summer health, most of us think about water bottles, shade and sun cream. The Medicines and Healthcare products Regulatory Agency, better known as the MHRA, says there is another part of the picture that many people miss: the medicines in your cupboard. In its 'Summer-proof your health' campaign, the agency is reminding people that some prescription and over-the-counter treatments can make it harder for the body to stay hydrated, regulate temperature or handle strong sun. That warning matters because the symptoms can look ordinary at first. Feeling wiped out, dizzy or more sunburned than usual may seem like typical hot-weather trouble, but the MHRA says medicines can sometimes be part of the reason.
Dr Alison Cave, the MHRA's Chief Safety Officer, says some common medicines change how the body responds when temperatures rise. Diuretics, often used for blood pressure or heart conditions, can increase fluid loss and make dehydration more likely. Some antidepressants and antipsychotics can affect temperature control, while beta blockers may reduce the body's response to heat stress. **What this means for you:** if you already know summer leaves you feeling drained, your medicine list is worth checking. The point is not to alarm you. It is to help you notice that heat and medicines can interact, and that ordinary safety steps may matter more than you realised.
The second issue is sunlight. The MHRA says some medicines can cause photosensitivity, which means your skin may burn faster or more severely than you expect. Antibiotics such as doxycycline and tetracycline are on that list, as are acne treatments including isotretinoin and topical retinoids, and the antifungal medicine voriconazole. The same warning applies to some disease-modifying antirheumatic drugs, or DMARDs, including methotrexate and azathioprine, which are used for conditions such as rheumatoid arthritis, psoriatic arthritis and lupus. The agency also notes a very low risk of a lupus-like skin reaction with proton pump inhibitors, or PPIs, after sun exposure, and says common painkillers such as ibuprofen and naproxen may also increase sun sensitivity.
**Plain English:** photosensitivity does not always mean hours in blazing sunshine. It can mean that the amount of sun that normally feels manageable for you suddenly is not. That is why the MHRA's advice is deliberately simple: drink enough water, avoid the strongest sun in the middle of the day, and use protective clothing and sunscreen to reduce the chance of a problem. There is also a good habit hidden in the small print. Every medicine comes with a patient information leaflet, and the MHRA says it is worth checking for advice on sun exposure and hydration. If you have lost the paper copy, the same information can be found online through the MHRA's medicines information service.
The signs to watch for are not complicated, but they are easy to brush off. The MHRA says dizziness, headaches, unusual fatigue, confusion or reduced urination can all be clues that your body is struggling in the heat. If your skin becomes red, sore, blistered or reacts much more strongly than usual after being in the sun, that may also point to medicine-related sensitivity. **What it means:** summer side effects do not always arrive with a dramatic warning. Sometimes they look like tiredness, thirst or 'a bit too much sun'. The value of this guidance is that it gives you a reason to take those signs seriously.
One point in the MHRA advice is especially important: do not stop taking prescribed medicines just because the weather is hot. If you are unsure whether your treatment affects hydration, temperature or sun exposure, speak to a pharmacist or GP before making changes. That applies even if the medicine is common or familiar. Everyday treatments can still have summer-specific risks. This is where clear health advice matters. The safest response is usually not guesswork, and it is not pushing through symptoms. It is checking the leaflet, lowering your heat and sun exposure where you can, and asking a professional if something does not feel right.
The MHRA is also asking people to report suspected side effects, because safety advice improves when more people share what they experience. You can raise concerns with a doctor, pharmacist or nurse, and you can also report a side effect directly through the MHRA Yellow Card scheme. The system now lets people create or access an account using NHS login. For readers, the wider lesson is a useful one. Summer health is not only about the weather forecast. It is also about how your body, your medicine and your daily routines meet on a hot day. The MHRA's message is straightforward: a quick check now can help you avoid a much harder afternoon later.