Excessive Sweating (Primary Focal Hyperhidrosis)

Primary focal hyperhidrosis is excessive sweating localized to the palms, soles of the feet, head, face, and armpits without any underlying conditions such as neurological diseases or drugs that prompt excessive sweating.
If the excessive sweating is localized to the palms or soles of the feet, the condition is referred to as ‘primary palmoplantar hyperhidrosis.’ In the same way, if the sweating is prominent only on the head and face, then the term ‘primary craniofacial hyperhidrosis’ applies. Whereas if the sweating is prominent only on the armpits, the condition is referred to as ‘primary axillary hyperhidrosis.’
Therefore primary focal hyperhidrosis is excessive sweating localized on the palms, soles of the feet, head, face, or armpits, or it can also occur on several of these areas simultaneously.

Although there is no clearly known cause to primary focal hyperhidrosis, the condition is thought to be a result of hyperactivity of sweat glands in the area.

By contrast, focal hyperhidrosis that has obvious causes, such as neurological diseases or certain drug administrations, is referred to as ‘secondary hyperhidrosis’.
When excessive sweating is not localized on the palms, soles of the feet, head, face, or armpits, then the condition is referred to as ‘generalized hyperhidrosis’.

It is estimated that the prevalence of primary focal hyperhidrosis is about 5% of the population worldwide (it depends on the statistics) and less than 50% of the hyperhidrotic patients seek medical attention.

People sweat in a hot summer day or because of exercise. This occurs in order to cool the body, i.e. to prevent it from overheating. This type of sweating is caused by thermal stimuli (thermal sweating) and is a normal physiological response. People may sweat when they feel anxious, stressed, or excited (emotional/psychological sweating), or when they eat hot/spicy food (gustatory sweating).

Sweat comes out from sweat glands called ‘eccrine sweat glands.’ Sweating occurs once the receptors receive a substance called ‘acetylcholine,’ which is released from nearby sympathetic nerves after the brain perceives thermal or psychological stimuli (Figure 1).

The affected area is influenced by the type of stimuli that provoke sweating. Psychological stimuli appear to mainly provoke sweating on the palms and soles of the feet. This sweat is caused by emotional stress such as fear, anxiety or excitement as seen when you have ‘sweaty hands.’ On the other hand, both thermal and psychological stimuli can cause sweating in the armpits. For example, one could break into a cold sweat without thermal stimuli indicating that a cold sweat is caused by psychological stimuli. Gustatory stimuli, in addition to thermal and psychological stimuli can cause sweating on the head and face.

In primary focal hyperhidrosis, these sweating processes occur at the level where they may interfere with one’s daily activity (Figure 2).

Several diagnostic approaches or criteria have been reported to date. The following is an example of the aforementioned criteria.

A diagnosis can occur if excessive sweating continues for six months or longer, along with four or more of the following seven items*:


1. Sweating occurs in the axillary (under the armpits), soles of the feet, palms, face, or head
2. Sweating is not isolated to one side of the body
3. Sweating is absent at night
4. Sweating occurs at least once a week
5. Sweating begins at 25 years of age or younger
6. There is a family history of hyperhidrosis
7. Symptoms cause impairment in daily activities


Some examples of an impairment in daily activities, according to our patients diagnosed with hyperhidrosis, are the following:
・pieces of paper given at school get blotchy with sweat
・pencils become slippery due to sweat
・noticeable sweating on the head occurs when others are not sweating

As an assessment method of the extent of sweating, various methods have been reported. We, at the clinic, use a special sheet that turns black as it gets into contact with water. Photo 1 was taken 1 minute after a patient with severe primary palmoplantar hyperhidrosis placed his palms on the sheet. In the case of primary palmoplantar hyperhidrosis, the degree of sweating varies depending on the timing of the measurement and other factors, but we believe it is useful as a reference.

An index of the severity of primary focal hyperhidrosis, HDSS (Hyperhidrosis disease severity scale) is the frequently used index that divides levels of severity of sweating into four degrees according to the degree to which sweating interferes with daily activities. Item 3, and 4 are considered as severe.


How would you rate the severity of your hyperhidrosis?

1. My sweating is never noticeable and never interferes with my daily activities.
2. My sweating is tolerable but sometimes interferes with my daily activities.
3. My sweating is barely tolerable and frequently interferes with my daily activities.
4. My sweating is intolerable and always interferes with my daily activities.

In addition to the conventional treatment of primary focal hyperhidrosis with topical aluminum chloride (thought to be effective by occluding eccrine sweat glands: not covered by national health insurance), topical anticholinergic agents such as Ecclock gel® and Rapifort Wipes® for axillary hyperhidrosis are now covered by insurance, which broadened the therapeutic options.
We also offer treatment with ‘tap water iontophoresis’ at the clinic for patients with palmoplantar hyperhidrosis (palms and soles), which is covered by national health insurance.