Sweaty feet

What is hyperhidrosis, and how common is it?

Hyperhidrosis (excessive sweating) is sweating that goes beyond what your body needs to cool down¹. It happens at rest, whatever the temperature, and is unpredictable and uncontrollable²¹. It most often affects the armpits, palms, soles and face, though it can affect any part of the body¹. When it affects the soles, it's called plantar hyperhidrosis (sweating of the soles).

Around 3 in every 100 Australians experience excessive sweating, meaning heavy perspiration with no obvious cause, even when they are neither warm nor exerting themselves; estimates differ across countries and definitions, and none is specific to the feet³. The sweating can also take a toll on how you feel day to day².

It can help to note where you sweat, how often, and whether it happens at rest or at night.

What causes sweaty feet, and who gets it?

Most excessive sweating has no known cause³. Doctors call this primary (or idiopathic) hyperhidrosis, and it often affects the feet, on both sides³⁴. It often runs in families, and it commonly starts in childhood or the teens through to the mid-twenties³⁵⁶. Emotional stress is a common trigger, because the sweat glands on the soles respond mostly to emotion⁷. Hot weather can make it worse, and so can strain or tiredness of the foot⁷. Negative emotions and sweating may also feed each other, with negative feelings both following from sweating and making it worse⁸.

Secondary hyperhidrosis is sweating caused by another condition or a medicine⁴. Hormone conditions such as diabetes and an overactive thyroid may be among the more common conditions behind it⁹.

It can help to note when your sweating began and what seems to bring it on, such as emotion, heat or footwear.

What does it feel like, and how is it diagnosed?

Plantar hyperhidrosis (sweaty feet) affects both feet equally¹⁰. The sweating can range from mild to severe and constant, but it stops when you're asleep¹⁰.

Primary hyperhidrosis is usually diagnosed from your history and an examination, once symptoms have lasted at least 6 months¹¹. They'll ask where you sweat, what sets it off, when it began and how often it happens⁵.

Some features suggest another cause, sometimes a serious one¹. Features that can point to another cause include:

• night sweats, a fever or feeling unwell¹²¹³;
• sweating on one side only, or over larger areas of your body¹³¹⁰;
• a sudden change in your sweating, or sweating that started at 25 or older³¹³;
• palpitations (a racing or pounding heartbeat)⁵.

Sweaty feet shouldn't be assumed harmless without an assessment¹.

What helps first?

Self-care comes first. A strong aluminium chloride antiperspirant is usually the first treatment⁴¹⁴. Apply it at night to clean, dry skin and wash it off in the morning, following the directions¹². It often irritates the skin¹⁴; if yours does, stop or reduce it.

Rotate your shoes, choosing leather or non-occlusive pairs, and let them dry between wears⁷¹². Wear moisture-absorbing socks and change them at least twice a day¹²⁷.

Iontophoresis is another option a clinic can provide for the feet⁴¹⁵. Tell the clinic about any cuts, infection or skin conditions first¹⁶. Iontophoresis is not suitable for everyone, for example people with a pacemaker or implanted defibrillator, an arrhythmia, uncontrolled epilepsy, recent wounds at the site, or pregnancy.

These treatments may help, though it isn't clear how well they work on the feet².

What helps if that isn't enough?

Your GP may refer you to a dermatologist (a skin doctor)¹¹. Anxiety and depression are common in primary hyperhidrosis, and doctors should take them into account when treating it¹⁷.

Options a doctor can discuss include iontophoresis, botulinum toxin, anticholinergic tablets, other procedures¹⁸ and surgery, though it isn't clear yet how well most of these work². These are prescription treatments and procedures, so they aren't self-care. Anticholinergic tablets and surgery carry side-effect risks. Surgery on the nerves that control sweating often causes sweating elsewhere on the body¹⁹.

How long does it last, and how do I keep it under control?

Sweaty feet usually need ongoing management rather than a one-off fix. Antiperspirants often need long-term use¹¹, so check now and then that your routine is still working.

Keep up the shoe and sock habits above, such as rotating leather shoes and changing moisture-absorbing socks at least twice a day²⁰. Loose clothing, and avoiding tight clothes and synthetic fabrics such as nylon, may also help²⁰.

Sweating can lower your quality of life and mood¹⁴²¹. Stress and sweating can feed each other⁸, and anxiety and low mood are commonly reported¹⁷. Notice whether stress or low mood make your sweating worse, and mention it to a health professional.

You may need support for anxiety or low mood alongside sweating treatment¹⁷¹¹.

It isn't clear yet whether anything stops sweaty feet coming back.

What can make it serious?

• You have lost weight without trying.
• You suddenly become short of breath, have chest pain or cough up blood.