Sweating is one of those bodily functions we don’t tend to think much about until it starts causing problems.
Most of us expect to perspire after a workout or when we’re trapped on a packed train with the heating inexplicably set to tropical rainforest levels.
Or, of course, during a heatwave. At this time of year, but especially during the current heatwave, most people will sweat more as warmer temperatures trigger the body’s cooling mechanisms.
When our internal temperature rises, whether because of exercise, hot weather, fever, stress, spicy foods or hormonal changes, a part of the brain called the hypothalamus, which acts as the body’s thermostat, sends signals via the nervous system to sweat glands in the skin, causing them to release sweat.
As the sweat evaporates from the skin’s surface, it takes heat energy away with it, helping to cool the body down.
It’s an elegant system that has served humans remarkably well for thousands of years.
Although it does struggle when it’s humid. Because there is already more moisture in the air, sweat evaporates less efficiently from the skin. This makes it harder for the body to lose heat, leaving you feeling hotter and stickier. In these conditions, it can help to cool the body more directly by using cool water sprays, taking lukewarm showers, staying well hydrated, slowing down and avoiding direct sun during the hottest parts of the day.
Dr Raj Arora says she regularly meets patients who are embarrassed by excessive sweating
In some people, however, the body’s natural cooling system becomes a little overenthusiastic. It’s a bit like having a smoke alarm that sounds every time somebody makes toast. For them, sweating is a daily frustration, appearing at inconvenient moments and in quantities that seem entirely disproportionate to the situation. And this hot weather can make an already troublesome problem feel significantly worse because the body’s normal cooling response is being added to an already overactive sweating system.
It can have a major impact on people’s lives.
As a GP, I regularly meet patients who are embarrassed by excessive sweating.
Some avoid shaking hands because their palms are constantly damp. Others stick to black clothing year-round to disguise underarm patches. Many have spent years assuming they simply have to live with it. It’s often only when they start talking about it that they realise just how much it has affected them. They may avoid social events, worry constantly about visible sweat marks, decline opportunities involving public speaking or become anxious about close personal contact. Something as simple as signing a document can become stressful if the paper ends up damp by the time they’ve finished.
Understandably, this can take a toll on confidence and wellbeing.
Some fear their excessive sweating is caused by poor hygiene and become overly concerned about staying clean. Others see it as a sign of weakness or assume they are simply an anxious person.
The reality is that excessive sweating, known medically as hyperhidrosis, is a recognised condition, thought to result from overactivity in the nerve signals that stimulate sweat glands, and there are treatments available that can make a significant difference.
The key distinction between sweating and hyperhidrosis is that sweating serves a purpose.
Hyperhidrosis occurs when the body produces significantly more sweat than is necessary for temperature regulation. The sweating often occurs without any obvious trigger.
It is surprisingly common. Studies suggest that around 2 to 5 per cent of the population are affected, with men and women affected in broadly similar numbers, although women may be more likely to seek medical advice.
In many cases, the sweating is localised to specific areas such as the hands, feet, underarms or face. These areas contain particularly high concentrations of eccrine sweat glands, which are responsible for most of the body’s temperature-regulating sweat. The palms and soles are especially rich in these glands, which helps explain why they are commonly affected.
As a general rule, it’s worth speaking to your GP if sweating is affecting your quality of life or interfering with work or social situations
In others, excessive sweating affects much larger areas of the body.
It’s thought the problem lies not within the sweat glands themselves but with the nerve signals controlling them. Certain groups of sweat glands appear to receive disproportionately strong stimulation from the nervous system.
There is also a psychological component. Stress, anxiety and embarrassment naturally trigger sweating because the body’s fight-or-flight response activates sweat glands, particularly in the palms, soles and underarms. This response evolved to improve grip and prepare the body for action in stressful situations.
Unfortunately, this can create a vicious cycle. Someone becomes anxious about sweating. That anxiety causes more sweating. And so the cycle continues.
The most common form of the condition is known as primary hyperhidrosis. This usually begins during childhood or adolescence and affects otherwise healthy individuals, and often runs in families. This type appears to involve overactive nerve signals between the brain and the sweat glands.
With secondary hyperhidrosis, the excessive sweating is caused by another medical condition or medication and is often linked to underlying problems affecting temperature regulation or hormone levels.
Conditions such as an overactive thyroid gland, diabetes, infections, obesity, neurological disorders and hormonal changes associated with menopause can all contribute. Certain medications can also increase sweating. Common culprits include antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs), some painkillers such as opioids, medications used for diabetes and certain treatments for high blood pressure.
Unlike primary hyperhidrosis, secondary hyperhidrosis often causes more widespread sweating and may be particularly noticeable at night, as the underlying conditions responsible, such as infections, hormonal fluctuations or certain cancers, can affect temperature regulation during sleep.
Conditions such as an overactive thyroid gland, diabetes, infections, obesity, neurological disorders and hormonal changes associated with menopause can all contribute to sweating
This is why it’s important not to dismiss excessive sweating.
While the vast majority of cases are not caused by anything serious, a sudden change in sweating patterns, particularly if accompanied by symptoms such as weight loss, persistent fevers, palpitations or drenching night sweats, should be assessed by a healthcare professional.
As a general rule, it’s worth speaking to your GP if sweating is affecting your quality of life, interfering with work or social situations, waking you at night, or if it has developed suddenly later in life.
Many assume ordinary antiperspirants simply don’t work for hyperhidrosis. In reality, standard products are often not strong enough rather than being ineffective altogether.
Fortunately, treatment options have improved considerably.
For many people, the first step is using a prescription-strength antiperspirant containing aluminium chloride. These products work by temporarily blocking sweat ducts and can be highly effective, particularly for underarm sweating.
Certain medications known as anticholinergics can reduce sweating by blocking the nerve signals that stimulate sweat glands.
While effective for some, anticholinergic medications are not suitable for everyone, particularly people with certain types of glaucoma or urinary retention problems, as they can worsen these conditions. They can also cause side-effects including dry mouth, constipation, blurred vision and difficulty passing urine.
Iontophoresis sounds like something devised by a maverick Victorian scientist, but it has been used safely for decades
Some patients benefit from iontophoresis. This involves placing the hands or feet in shallow trays of water while a very mild electrical current passes through. It sounds like something devised by a maverick Victorian scientist, but it has been used safely for decades and can work remarkably well for sweaty hands and feet. It appears to temporarily disrupt the signals between nerves and sweat glands and may also reduce sweat production by altering sweat duct function.
The main drawback is that regular maintenance treatments are usually needed to sustain the benefits, often every one to two weeks, although this varies considerably between individuals.
Availability varies across the NHS and home devices typically cost several hundred pounds.
Botulinum toxin injections can also be highly effective, again temporarily blocking the nerve signals to the sweat glands.
For people with troublesome underarm hyperhidrosis, the results can be impressive. Many notice a significant reduction in sweating within a couple of weeks and the effects often last between four and 12 months before treatment needs repeating. In some parts of the UK, botulinum toxin treatment may be available through specialist NHS services.
Surgery may be an option for severe cases where symptoms significantly impair daily functioning.
The most common procedure, endoscopic thoracic sympathectomy, or ETS, involves interrupting specific nerves within the chest that stimulate sweating in the hands and sometimes the underarms. It can be highly effective, particularly for severe palmar hyperhidrosis, but it carries risks, including compensatory sweating, where excessive sweating develops elsewhere on the body after surgery.
This is why surgery is usually considered only when all other options have been exhausted.
In my experience, most patients find meaningful improvement long before surgery ever becomes necessary.
The most important message is that excessive sweating is absolutely nothing to be embarrassed about. It’s simply the result of sweat glands receiving signals they don’t necessarily need, and it’s something that can often be improved.
So if you find yourself carrying spare shirts, strategically choosing clothing colours based on sweat visibility, or greeting people with an apologetic warning about your handshake, speak to your GP.
Dr Arora is an NHS GP based in Surrey.
Instagram: @dr_rajarora; TikTok: @drrajarora
