Sweating is controlled by parts of the brain, which sends signals along nerves to the small sweat glands in the skin. These nerves are part of the “autonomic nervous system” that controls many unconscious body functions. Some of these functions, including sweating, are called “sympathetic”, which is different from the everyday use of the word and does not suggest any emotional meaning.
Increased sweating is a normal response to a rise in body temperature, and to emotions like anxiety.
Antiperspirants reduce sweating and are different from deodorants, which reduce odour, usually through an antibacterial effect. The two are often combined in the same product.
Visible sweat, wet clothes and a clammy handshake can be embarrassing, and can interfere with work and personal relationships.
Hyperhidrosis affects the water-producing (“eccrine”) sweat glands, and not the “apocrine” sweat glands that produce the more oily type of sweat that causes odour, especially under the arms. Therefore odour is not a direct result of hyperhidrosis. However, if sweaty feet get soggy inside shoes, overgrowth of skin bacteria can cause a bad smell.
Your doctor will assess which kind of hyperhidrosis you have. Depending on the type, you might have tests for an infection, diabetes, thyroid overactivity or other conditions.
When there is an underlying cause that can be treated, the hyperhidrosis can be cured. Surgical treatment can cure some people, but is often associated with side effects and is therefore considered only if other modalities have failed. Otherwise, the aim is to control the condition.
Botulinum toxin derived from bacteria can be injected into the skin in very small carefully controlled doses to block the action of the nerves which activate the sweat glands. This treatment usually works very well and usually lasts between two and six months, although some patients may continue to benefit for 12 months and the treatment can be repeated. Botulinum toxin is most commonly used for underarm sweating, and it is not suitable for large areas. The skin can be numbed with an anesthetic cream or injection, but underarm skin is not very sensitive and many people do not need this. Botulinum toxin is less commonly used in the palms and soles because it can cause temporary weakness of the hand and foot muscles and is painful to have administered.