Causes Of Excessive Underarm Perspiration

The International Hyperhidrosis Society estimates that millions of people, or about 3 percent of the world's population, suffer from excessive sweating. Hyperhidrosis, or excessive sweating, causes a person to sweat as much as four or five times more than the body needs to keep itself cool. There are two types of hyperhidrosis, primary focal hyperhidrosis and secondary general hyperhidrosis.

Genetics

Primary focal hyperhidrosis is excessive sweating where sweating itself is the medical condition and is not caused by secondary factors. It is focal, meaning that it occurs in specific areas of the body, such as in the armpits, and symmetric, meaning that it occurs in the same areas on both sides of the body.
Excessive sweating in the armpits, when not caused by another underlying medical condition, by medication or in response to an emotional trigger, is an example of primary focal hyperhidrosis.
Often, focal hyperhidrosis begins in adolescence, according to the Mayo Clinic. Generally speaking, the sweating occurs at least once a week and only when the person is awake, possibly because the body's resting temperature is highest during the daytime hours, according to Nikos Drakos in his paper, "Regulation and Control of Body Temperature." The International Hyperhidrosis Society points out that research indicates that primary focal hyperhidrosis has a genetic link and that different members of the same family suffer from it, so if one family member sweats excessively in the underarm region, the likelihood is that other family members will, too. The Center for Excessive Sweating reports that 15 percent to 50 percent of individuals with hyperhidrosis have a family history of the disease.

Underlying Causes

Secondary general hyperhidrosis is caused by an underlying factor, often as a side effect of medication or as a symptom of another medical condition. This type of perspiration occurs wherever there are sweat glands, including in the underarm regions. If a person has inherited an excess of sweat glands in the axillary (underarm) region, the excessive sweating will occur there. Medical conditions that can cause excessive perspiration include puberty, when the body begins to produce high levels of androgens; menopause, when a woman's hormones fluctuate; and diabetes, because poor glucose maintenance can damage the nerves that "turn on and off" sweat gland production.
Excessive underarm perspiration can also result from surgical treatment of palmar (hands) or plantar (feet) hyperhidrosis. Endoscopic thoracic sympathectomy severs the nerves that cause an overproduction of palmar and/or plantar sweat. The International Hyperhidrosis Society indicates that a high number of people--up to 80 percent in one study--who undergo this surgery begin compensatory sweating in another area of the body, such as the underarm area.
If the underlying condition is treated or, if caused by medication, when the medication is stopped, the excessive sweating ceases.

Emotional Sweating

The Hyperhidrosis Center reports that emotional sweating usually occurs on the palms and soles, called palmar/plantar hyperhidrosis, or in the underarms, called axillae hyperhidrosis. Emotional sweating occurs when a person is in a state of high arousal. Fear, embarrassment and anger are examples of high arousal. In their book, "Neonatal Skin," authors Steven Hoath and Howard Maibach call emotional sweating a "vestigial" response of the body's fight-or-flight reflex.