Dripping in sweat, dehydrated and unable to cool down... Why these drugs taken by nine million of us could be the reason you struggle to cope in a heatwave - and how to beat it: ALICE SNAPE

I’ve only just stepped out of my front door and I’m already covered in a thick layer of sweat.My hair’s damp at the nape of my neck, and I can feel it trickling down my shoulder blades and back. I’ll be a puddle by the time I’ve got to the train station – let alone my destination.Good job I packed a few spare tops so I won’t have constant sweat patches.These relentless British heatwaves have hit me hard. I used to adore the hot weather, craving an intravenous drip of summer all winter. I was the type of woman with ice blocks for hands – ‘cold hands, warm heart’, I’d retort when someone recoiled at their sub-zero temperature – so I revelled in the heat.Oh, how I long for those days.Nowadays, you see, my bodily thermostat seems to be broken, cranked right up like a creaky old radiator.I get a prickly sensation on my skin and my mouth feels like it’s stuffed with cotton wool – yet weirdly I don’t feel thirsty, so I keep forgetting to drink. Sweat pours off me in buckets. My brain’s foggy and focusing on anything other than trying to stay cool has been all-consuming.Given I’m 43, you may wonder if perimenopause might be to blame. But that’s not the culprit. Alice Snape's medication has meant her bodily thermostat is 'cranked right up like a creaky old radiator' and sweat 'pours off [her] in buckets'Turns out, the medication that has pulled my mind out of a very dark place also means my body is struggling to function in these extreme temperatures.For the past two years, I’ve been taking the antidepressant Sertraline for depression, anxiety and Obsessive Compulsive Disorder (OCD). It’s not just saved my life, it’s made my life worth living again.When my GP first prescribed it to me, I was at breaking point. They listed various side effects but, to be honest, the only potential repercussions I really took note of were the likelihood my libido would plummet and that I shouldn’t drink grapefruit juice.Who drinks that? I thought, before, of course, immediately craving grapefruit juice.If they did mention an increased sensitivity to heat, I suspect my only – misguided – thought would have been that it might be useful for my chilly fingers.There’s over 8.7 million people in England prescribed at least one antidepressant. The most common are selective serotonin reuptake inhibitors (SSRIs), like sertraline, citalopram and fluoxetine. They work by increasing serotonin levels, the ‘happy hormone’ in the brain, then blocking the breakdown of it. In non-medical terms, filling your head with joy then putting in a plug to stop it draining away.All good, in theory, but SSRIs also impact the hypothalamus, the part of the brain that regulates body temperature, making it much harder to keep cool. They can also interfere with your natural sweating mechanisms.Not ideal when it’s hotter than season two of Rivals out there.It’s an issue that hits women harder (what doesn’t?), as hormonal fluctuations exacerbate heat intolerance. NHS GP Dr Helen Wall says this is why I’m now a Very Sweaty Person.However, some people actually sweat less than normal whenon SSRIs. ‘Both can be problematic,’ she tells me. ‘If you’re sweating excessively that increases your risk of dehydration, whereas if you’re not sweating like you should, then that’s limiting your body’s ability to cool down because that’s what we use sweating for.’SSRIs also interfere with saliva production, so users often experience a very dry mouth, which Dr Wall says can ‘confuse normal thirst signals meaning some people become more focused on nausea or feeling overheated rather than recognising thirst’.Even if you don’t feel thirsty you’re still losing fluid through sweating (sometimes up to a litre an hour if you’re active in hot weather), and you lose water every time you breathe, she warns, ‘so it’s easier to become dehydrated without realising it’.She recommends setting an alarm to remind me to drink even if I don’t feel like it. I’ve taken to putting a jug in the fridge and ensuring I glug the whole lot before the day is through.Dr Wall also suggests consuming drinks with electrolytes to replace the salts we lose in sweat; I’m a big fan of coconut water, which naturally hydrates the body more effectively than water. A bottle after the gym is already my go-to. Temperatures have been sweltering in Britain, which has experienced countless heatwaves throughout the summerSpeaking of which, Dr Wall recommends only exercising early in the morning and late at night when the temperature drops.She advises using a damp towel (I put a tea towel in the freezer) around your pulse points at your neck and wrists. ‘This can be really effective because it cools that blood flowing through the large vessels,’ she explains. She also suggests only opening your windows at night, when cool – rather than hot – air can circulate.Most importantly, Dr Wall warns not to skip a dose of medication even if it’s making the heat feel unbearable, as it can lead to withdrawal symptoms including dizziness, headaches, nausea, fatigue, brain fog – and a return of anxiety. The heatwave will only exacerbate this.If it’s becoming a real issue, contact your GP, as heat exhaustion can sometimes progress to heat stroke – a medical emergency.Usually I might pour myself a crisp cold glass of rose to cheer myself up, but Dr Wall advises to cut back on the alcohol (it’ll just dehydrate you).So here’s to an evening on the sofa with an icy glass of water with added electrolytes and a damp tea towel worn as a scarf.Cheers to that.@doctorhelenwall