Hyperhidrosis

What is hyperhidrosis?

Hyperhidrosis is the medical term for sweating that exceeds what the body needs for temperature control. It comes in two broad forms. Focal hyperhidrosis targets specific areas like hands and underarms, while generalized hyperhidrosis affects the whole body and is more often linked to another cause.

In focal hyperhidrosis, the nerves supplying sweat glands in particular regions are overactive, producing sweat unrelated to heat or effort.

Last updated Jul 11, 20262 min read

Quick answer

The short answer

In focal hyperhidrosis, the nerves supplying sweat glands in particular regions are overactive, producing sweat unrelated to heat or effort.

This form typically starts in childhood or the teenage years and often runs in families.

Generalized hyperhidrosis, by contrast, involves widespread sweating and may accompany infections, hormonal changes, or medications.

The distinction matters because focal sweating is usually a standalone trait, while generalized sweating more often points to an underlying trigger worth investigating.

The glands themselves are normal in number and structure; the problem lies in the nerve signals telling them to fire.

Focal sweating tends to be symmetric, affecting both hands or both underarms rather than a single side.

Because the sweating strikes visible, high-contact areas, its burden is often more social and practical than it is physical.

A little more detail

The word can sound alarming, but for most people with the focal form it describes a long-standing, benign pattern rather than a new disease.

Confusing the two forms leads to unnecessary worry, so the location and history of the sweating are key details.

As a rule of thumb, focal sweating you have had since youth is usually its own trait. Sweating that is new, generalized, or one-sided deserves a closer look.

Sweating that occurs during sleep points away from primary focal hyperhidrosis, which typically pauses when you rest, and toward a possible underlying cause.

When to check with a clinician

Sweating that is generalized, newly developed, or paired with fever, weight change, or night sweats warrants a clinician's evaluation for an underlying cause.

Key takeaways

Sweat beyond cooling needs
Focal targets specific areas
Generalized may signal a cause

Frequently asked questions

At what age does hyperhidrosis usually start?

The focal type commonly appears in childhood or adolescence, while generalized sweating that begins later in life more often has an identifiable trigger.

Is hyperhidrosis common?

It is more common than many assume, though it often goes unmentioned because people treat it as a personal quirk rather than a recognized condition.

Does hyperhidrosis happen during sleep?

Primary focal hyperhidrosis usually stops during sleep, so sweating that soaks you at night points more toward a generalized cause worth investigating.

Sources & further reading

Reputable organizations with more on sweating and related topics. Offered for further reading and general education, not as citations for any specific claim on this page.

General educational information about sweating. Not medical advice, and not a substitute for diagnosis or treatment by a qualified healthcare professional.