Sweating after a workout is standard. But anxiety, food and hyperhidrosis-induced sweats can leave an emotional mark. Here, Lizzie Pook explores the science of sweating
‘I shower three times a day, wear only black clothes and avoid slip-on shoes, because my feet slide right out of them. Sometimes, even holding a pen is impossible,’ says Kate, 35, who has suffered from hyperhidrosis since she was a teenager. Thought to affect five per cent of the population, abnormally excessive sweating can make summer something to dread.
‘Work meetings are the worst. Even with air-con, I have to change several times a day and I avoid shaking hands with people because I feel self-conscious,’ adds Kate, an investment broker from Manchester, who has been prescribed glycopyrronium bromide tablets to tackle the problem. ‘They stop the sweating if you catch it in time, but they leave me with a dry mouth and eyes all day, so eating certain foods, like bread, and using my contact lenses is uncomfortable.’
What causes excessive sweating?
In extreme cases of hyperhidrosis – thought to be caused by a problem in the nervous system – electric-current therapy, surgery and even Botox can be effective. Botox paralyses the sweat glands so that nerve signals cannot be received and requires 20-40 injections per armpit, but the effects can last up to eight months, which is a game-changer for sufferers.
For the rest of us, who can lose up to 12 litres a day in anxiety-induced sweats or excessive perspiration caused by diet or hormones, summer can make for an uneasy few months. ‘Women experience a spike in body temperature during ovulation, due to an increase in progesterone levels, which leads to sweating,’ says Dr Joanna Gach, consultant dermatologist at Spire Parkway Hospital in Solihull. ‘Similarly, during pregnancy and just before menstruation, our body temperature rises, causing us to sweat more.’ One study by Charles University in Prague actually found that the sweat of a woman who is ovulating smells sweeter than that of a woman who is not.
Of course, the core function of sweating is not to embarrass us on first dates or in the boardroom, it’s to cool us down. ‘When our temperature rises due to environments, physical activity or hormones, our thermoregulatory centre, in the brain’s hypothalamus, responds by telling our body to secrete sweat to bring our temperature down,’ says Dr Riccardo Di Cuffa, director and GP at Your-doctor.co.uk. So why do some of us have an under-boob area as wet as a rainforest (or is that just me?), while others can remain bone-dry despite a heatwave? ‘Some people naturally have a higher distribution of sweat glands than others,’ explains Dr Adam Friedmann, consultant dermatologist at the Harley Street Dermatology Clinic. ‘We all sweat in different ways and in different places, according to the genetic distribution of autonomic nerve fibres.’
Why do I start sweating when I’m nervous?
Interestingly, where you sweat also matters. ‘Emotional sweating that is brought on by nervousness or anxiety is targeted to the palms and soles,’ says Dr Justine Kluk, a London-based consultant dermatologist. ‘Whereas sweating on larger body-surface areas, such as the lower back and underarms, is more likely to be a response to exercise, warm weather or claustrophobic environments.’ And those little beads on your nose after eating a chicken tikka masala? That’ll be the capsaicin – the primary spicy chemical in peppers and chillies that causes your body to react as if it were in a very hot environment.
‘Gustatory sweating – triggered by the food we eat – is indicated by perspiration on the forehead, upper lip, scalp and neck, occurring just moments after eating,’ says Dr Kluk. ‘This can be provoked by damage to the nerve that passes through the parotid (salivary) gland in people who have had surgery or trauma to the neck, but a degree of gustatory sweating can also be a normal response to eating hot or spicy food. Other triggers are citric acid, coffee, chocolate and, bizarrely, peanut butter –thought to cause a mild allergic reaction.’ Low blood-sugar levels will also kick-start a fight-or-flight response as your body senses a lack of fuel. You therefore produce more adrenaline, which causes excess sweating.
How to stop excessive sweating
If you want to keep sweat under control but it’s not bad enough to have you heading for the doctor, try avoiding garlic, anything with excess sodium (such as fast food) and high-fat milk. Smoking, alcohol and caffeine should be off-limits, too. Nicotine causes our bodies to release acetylcholine, a chemical that stimulates sweat glands. Caffeine triggers the central nervous system to send ‘go’ messages to the sweat glands, while alcohol leads to vasodilation, a widening of the blood vessels, which carries heat to the surface of the skin.
There is an upside to sweat, though: it’s sexy. Our pheromones – the chemical signals secreted through our sweat glands – are powerful things, and scientists from Utrecht University in the Netherlands have found evidence to suggest that humans communicate positive emotions, such as happiness, through the smell of our sweat. Similarly, research by Rice University in Texas suggests we can sense fear in other people’s sweat.
Androstadienone, which derives from the male hormone testosterone, can influence women’s moods and increase sexual arousal, according to studies by the University of California, Berkeley. Research also suggests we use subtle smell cues to help select our sexual partners (subconsciously we’re looking for a mate with a different set of immune system genes to ours), hence the recent trend for pheromone dating events where women choose their prospective partner by sniffing a T-shirt worn by each hopeful date. When it comes to love, it turns out you really should follow your nose.
What’s the difference between deodorant and antiperspirant?
Deodorant’s primary focus is to mask sweat so you smell fresher, whereas antiperspirants contain aluminium salt to actively prevent sweating.
Can antiperspirants cause cancer?
Antiperspirants that are aluminium based temporarily plug pores to stop sweating. That’s why they work better at night when sweat production is low and the active ingredient has time to be absorbed. Is this dangerous? Nothing has been proven, but some experts continue to research the risks, such as University of Reading’s Professor Philippa Darbre, who says, ‘If sweat can’t get out, there’s a build-up of toxins that can’t escape so the body retains chemicals.’ Is there truth in the myth linking antiperspirants to cancer? Despite studies into possible links between aluminium exposure and breast cancer, Alzheimer’s and Parkinson’s, the myths have been largely dubunked, and cancer charities aren’t concerned. Should we continue using antiperspirants? Our exposure to aluminium via antiperspirants is minimal so there’s no need to avoid them, though some – like Professor Darbre, who stopped using underarm products in 1995 – prefer to reduce their exposure to parabens. This may explain the trend for organic roll-on deodorants.
Best products to stop sweating
Neal’s Yard Remedies Peppermint & Lime Deodorant, £8 . The highly absorbent bamboo powder keeps you dry and antimicrobial shikimic acid neutralises odour for a two-pronged attack.
Wear layers, whatever the weather. Even a thin camisole can help absorb sweat from the skin’s surface.
Aurelia Botanical Cream Deodorant, £18 . This rich balm is packed with hydrating shea butter, antimicrobial arrowroot and kaolin to suck up sweat.
Breathing or relaxation techniques can reduce anxiety and decrease the stimulation of neurotransmitters that trigger sweat glands.
Soft & Gentle 0% Aluminium Dry Deodorant, £2.99 . An alcohol, paraben and aluminium-free spray formulated with naturally deodorising sage extract.
Avoid silk. Instead, wear breathable cotton or linen to keep you cool.