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23rd Jul 2021

Why people who take medication need to be extra careful in a heatwave

Laura Grainger

A number of common medications are associated with inhibiting the body’s ability to cope in heat.

We’ve had a stellar few days of cracking weather that we don’t often get on our lovely island.

But while everyone’s trying to make the most of fun in the sun, it’s important to remember a number of risks come with higher temperatures.

Met Éireann’s high temperature warning has been extended for another day and earlier this week, Chief Medical Officer Dr. Tony Holohan urged the public to exercise caution over the likes of sunburn, heat exhaustion and sun stroke.

But high temperatures can be even more dangerous for those who take medications to treat a wide variety of common conditions, disorders and health issues.

“We need to be mindful when medications mix with heat,” Aaron Bernstein, a paediatrician and interim director of the Harvard T.H. Chan School of Public Health’s Center for Climate, Health and the Global Environment, tells the Washington Post.

“Too much heat can make an otherwise safe and effective drug dangerous.”

Here are the conditions associated with drug treatments that may impair how the body copes with heat. If you take medication for any of these conditions, it’s important to be aware of how you’re feeling and take extra care of yourself in this weather.


By stimulating bowel movements, laxatives can cause diarrhoea and flush your body of too much water. The loss of fluids paired with excessive heat can quickly lead to dehydration.

Depression and/or anxiety

The side effects of antidepressants can include diarrhoea, vomiting and excessive sweating. These are generally worse when the medication is first started, but can continue to varying degrees. As a result, those who take anti-depressants are more prone to dehydration.

High blood pressure and/or fluid retention from heart failure

Diuretics make the body lose water, which makes us more prone to dehydration. Along with beta blockers and ACE inhibiters, they also lower blood pressure, making dizziness and fainting more likely in heat.

Migraines and headaches

Excedrin migraine relief tablets contain a mix of acetaminophen, aspirin, and caffeine. The caffeine is supposed to enhance the pain relief of acetaminophen, but can reportedly have a diuretic effect that could lead to dehydration.

Psoriasis and/or psoriatic arthritis

Another drug with a possible side effect of diarrhoea, those who take apremilast for psoriasis or psoriatic arthritis need to be aware of their body’s fluid loss and intake.

Polycystic ovary syndrome or Type 2 diabetes

A number of oral medication used to treat Type 2 diabetes can have a diuretic effect, but metformin, used to treat both Type 2 and PCOS, can cause dehydration in other ways. The drug is associated with side effects of gastro-intestinal upset and diarrhoea.


As cancer patients, survivors and their loved ones know, chemotherapy can come with a wide variety of side effects. Nausea and excessive vomiting are included, leading to a substantial loss of fluid. Those undergoing chemo in the summer should take particular care in staying hydrated and choosing water-rich foods.

Allergies, asthma, chronic obstructive pulmonary disease, Parkinson’s disease or other tremors

Those who take over-the-counter drugs for allergiesTiotropium bromide for asthma or COPD, or benztropine for Parkinson’s disease or other tremors should be aware that these drugs can reduce sweating. Where excessive sweating can dehydrate the body, reduced sweating can lead to overheating and heat stroke as sweat is the body’s natural way of cooling itself.

Disorders or psychological conditions such as ADHD, PTSD, OCD, BPD, schizophrenia, bipolar disorder, or Alzheimer’s disease

As antipsychotic drugs reduce or increase the levels of neurotransmitters in the brain, they can inhibit the brain’s ability to regulate body temperature. Those who take them are therefore more prone to overheating.

So what now?

If you take any of the listed medications, you can protect yourself by following the guidelines on preventing heat illness in general – though for you, it’s likely even more important to follow them than the average sunbather or beach-goer.

Keep an eye on forecasts, limit exercising to the morning or evening when temperatures are generally cooler, stay in the shade as much as possible and of course, drink lots and lots of water.

If you have to be outside for a prolonged period of time such as for work, let your doctor know in order to take precaution. They might adjust your dose based on your exposure to the heat or sun.

Whatever you do, don’t just stop taking your medications. You were obviously prescribed them for a reason, and quitting them cold turkey without medical advice could lead to a whole load of other issues.