What Is Hyperhidrosis? Symptoms, Causes & When to Worry

Introduction

Most people sweat when they're hot or exercising. But for an estimated 4-5% of the world's population, sweating is unpredictable, excessive, and deeply disruptive. This condition is called hyperhidrosis — and understanding it is the first step toward managing it.

What Is Hyperhidrosis?

Hyperhidrosis is a medical condition characterised by sweating that far exceeds what the body needs for temperature regulation. The word itself comes from the Greek: 'hyper' meaning over, and 'hidrosis' meaning sweating. It can affect specific body parts (focal hyperhidrosis) or the entire body (generalised hyperhidrosis).

The Two Types of Hyperhidrosis

Primary Focal Hyperhidrosis

This is the most common type. It affects specific areas — most commonly the palms, underarms, soles of the feet, and face/scalp. It typically begins in adolescence and is not caused by any underlying medical condition. The exact cause is thought to be an overactive sympathetic nervous system that signals sweat glands to produce more than necessary.

Key characteristics: symmetric (both hands or both underarms), occurs at least once a week, stops during sleep.

Secondary Generalised Hyperhidrosis

This type is caused by an underlying medical condition or medication. It tends to affect the entire body, can occur during sleep (night sweats), and typically begins in adulthood. Causes include thyroid disorders, diabetes, infections, menopause, obesity, and certain medications.

Common Symptoms of Hyperhidrosis

Visible soaking of clothing even in cool conditions

Wet, clammy handshakes

Difficulty holding pens, phones, or steering wheels due to slippery palms

Foot odour from constant moisture

Skin maceration (softening and breaking down) in affected areas

Avoiding social situations, physical contact, or activities due to sweating

What Causes Hyperhidrosis?

For primary hyperhidrosis, the sweat glands themselves are normal — it's the signals from the nervous system that are turned up too high. A strong genetic component exists: approximately 30-50% of people with primary hyperhidrosis have a family history of the condition.

Secondary hyperhidrosis triggers include: hyperthyroidism, menopause, diabetes mellitus, obesity, Parkinson's disease, lymphoma, and medications such as antidepressants and beta-blockers.

How Is It Diagnosed?

Doctors typically diagnose hyperhidrosis based on medical history and physical examination. A useful test is the starch-iodine test, where a starch-iodine solution is applied to the skin — it turns dark blue wherever sweating is excessive, visually mapping the affected areas.

Blood tests may be ordered to rule out secondary causes.

When Should You Be Worried?

Seek medical attention if: excessive sweating began suddenly in adulthood, it's accompanied by unexplained weight loss, you experience night sweats that disrupt sleep, or sweating is generalised (whole body) rather than focal.

The Good News: It's Treatable

Hyperhidrosis is one of the most under-diagnosed and under-treated conditions — not because it's hard to treat, but because many sufferers feel embarrassed and never seek help. Effective treatments range from clinical-strength antiperspirants to prescription medications, iontophoresis, Botox injections, and surgery in severe cases.