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Excessive Sweating (Hyperhidrosis)

What is Hyperhidrosis?

Hyperhidrosis means excessive sweating. Sweating is one of the most important ways in which the body loses heat; however, people with hyperhidrosis produce sweat in amounts far greater than needed to control their temperature.

There are two main types of hyperhidrosis:

Focal Hyperhidrosis is the more common type involving excessive sweating of the feet, hands and, in about 30% – 40% of cases, the armpits. The face may also be affected but less often. Even less common is gustatory Hyperhidrosis, when sweating on the face is triggered by hot or spicy food. Botox® is recommended for the treatment of focal Hyperhidrosis affecting the armpits (axillary Hyperhidrosis) when other treatments have not worked.

Generalised Hyperhidrosis affects the whole body. It is much less common and is usually cause
by another illness such as an infection, diabetes or when the thyroid gland is overactive. The
excessive sweating usually stops when the illness is treated.

How common is hyperhidrosis?
It has been estimated that up to 1% of the population has some form of Hyperhidrosis. It usually starts during the teens and twenties.

What are the causes of hyperhidrosis?

It is not known why some people are affected and others are not. About one third to half of people with Hyperhidrosis have a relative with a similar problem, suggesting that there might be a genetic cause.

Hyperhidrosis is caused by overactivity of one type of sweat gland, the eccrine gland. These glands are found all over the body surface but they are concentrated on the palms of the hands, the soles of the feet and in the armpits.

Many things can trigger normal sweating and this is also true for Hyperhidrosis – it is just the amount of sweating that varies. Examples of triggers include:

  • Exercise

  • Heat or cold

  • Alcohol, coffee or tea, smoking, hot or spicy food

  • Stress, anxiety or strong emotions

  • Certain times of the day

People with hyperhidrosis can produce a large volume of sweat. This means that the hands, feet, chest or armpits (depending on which part of the body is affected) may be constantly damp. This makes normal everyday activities more difficult to carry out and it can cause embarrassment at work or socially. However, it is not true that Hyperhidrosis causes body odour: the smell that some people think is due to sweating is in fact caused by bacteria if sweat remains there for a long time.

What can I do about hyperhidrosis?


  • Simple self-help measures you can take include:

  • Choose clothing that will keep you cool. Natural fibres are cool as they absorb sweat and can remain damp; some synthetic fibres are warm but they draw sweat away from the body and feel dry. Consider having a change of clothing available during the day.

  • Keep your environment cool and well aired.

  • Avoid the food and drinks that trigger sweating. This will be different for everyone but you will probably know what causes problems for you.

  • Reduce stress, tension and anxiety. These are common problems for everyone, though people with Hyperhidrosis have the extra difficulties of coping with sweating. Think about how you can reduce stress during the day, plan your activities carefully and make time to relax.

  • Pay attention to your personal hygiene. Odour can be reduced by taking frequent showers. Although this will not be convenient for people who constantly sweat it is an effective and simple measure to take.

What is Botox® and how does it work?

Botox® is a treatment given by injection into the skin. It is recommended for the treatment of hyperhidrosis in the armpits (axillae) and it has also been used for many years to treat muscle spasm affecting the eyes, face and neck. Botox® is also used to relieve muscle spasm in children with cerebral palsy.
Botox® is a very pure preparation of a protein, botulinum toxin type A, obtained from the bacteria Clostridium botulinum grown under modern methods of cultivation. When small doses are injected into the skin, Botox® blocks the actions of nerves that supply the eccrine glands; this prevents the glands from producing sweat. This means that the effects of treatment last on average for 6 months but eventually they will wear off.

What happens during a course of treatment with Botox® ?

Using a very fine needle, your doctor will inject a small amount (0.1ml – 0.2ml) of a solution of Botox® into 10 – 15 places about 1cm apart and spread evenly in each armpit. Sometimes a dye is used to show up the areas where sweating is greatest and where the injections should be placed.

Does it hurt?

The needles used are very fine so most people experience only mild discomfort. It is uncommon for pain relief to be required.

How quickly does it work and how long will the effects last?

You should notice some change for the better within a week of your treatment.
Different people have different responses to treatment. In a clinical trial, sweat production was reduced by 83% one week after treatment. Furthermore, sweating was reduced by at least half in 95% of patients. Your next treatment can be given when the effects of the first course wear off, this usually happens after 6 to 9 months.
Your doctor will advise you about when to return for further treatment.

What happens if I decide to stop treatment?

The effects of Botox® wear off over a period of 6 to 12 months. If you decide not to have any further treatment there will be no lasting change in the areas treated. Sweating will gradually return to the level it was before you started treatment.

Are there any side effects?

Every treatment has side effects in at least some patients. About 4.5% of patients experienced an increase in sweating in another part of the body.
Since the injection is made only into the skin, the effects of Botox® will be limited to the nerves supplying the sweat glands. Occasionally, a very small amount of Botox® may spread out from the injection site and affect a nearby nerve that supplies a muscle. In clinical trials, about 0.7% of patients experienced mild weakness of the arms; this did not last and got better without any treatment.
Because Botox® is a protein, there is a small chance that ‘flu-like’ symptoms (tiredness, mild fever, muscle aches) may occur; these will disappear within a few days. You may also feel a little discomfort at the injection sites.

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