Excessive Sweating/Hyperhidrosis

Why do we sweat?

Dr Shreya Andric Sweating Hyperhidrosis Dermatology Treatment Northern Sydney Derm.

In humans, sweating is essential for what is called thermoregulatory homeostasis, which is a process that allows your body to maintain its core internal temperature. There are two main mechanisms for cooling the body – radiative cooling where the blood vessels in the skin dilate (become wider) so that blood can flow away from your core to your skin where it is cooler, and evaporative cooling via sweat. Sweat, which is produced by the eccrine glands in the skin, results in loss of heat as it evaporates. Few mammals except humans and horses produce sweat in enough quantities for it to be effective in cooling the body.

There are 2-5 million eccrine glands distributed within the skin – importantly, none are found on the clitoris, glans penis, labia minora, external part of the ear, or lips. Apocrine sweat glands are concentrated in the hair follicles of the scalp, armpits and groin. These glands release a heavier, fat-laden sweat that carries a distinct odour, referred to as body odour. This smell occurs when apocrine sweat breaks down and mixes with the bacteria on the skin.

The average healthy adult can produce over 500mL of sweat per hour, 99% of which is water. Athletes or those acclimatised to hot environments can produce up to 3-4 litres per hour. Physically fit or acclimatised people begin sweating sooner and conserve sodium, chloride, and other electrolytes more efficiently. Thermoregulatory control is similar in men and women and only slightly reduces with age.

The most common areas of sweating on the body include:

  • Armpits

  • Face

  • Palms of the hands

  • Soles of the feet 

What triggers sweating?

Sweating is very normal and occurs regularly as part of life. There are, however, a variety of causes that can stimulate increased sweating:

  • High body or environmental temperatures

  • Emotions and stress – anger, fear, embarrassment, anxiety, emotional stress

  • Foods – especially spicy foods, caffeinated drinks, alcoholic beverages

  • Medications and illness

  • Menopause

A normal amount of sweating does not need specific medical treatment. In order to make yourself more comfortable and minimise your sweating:

  • Wear light layers of clothing that allow your skin to breathe

  • Remove layers as you heat up

  • Wash dried sweat off your face and body for optimum comfort

  • Change out of sweaty clothes to reduce the risk of bacterial or yeast infections and minimise the chances of developing back-ne!

  • Drink water to replace fluids and electrolytes lost through sweating

  • Apply underarm antiperspirant or deodorant to reduce odour and control sweating

  • Avoid foods that may increase your sweating.

Not sweating enough and sweating too much can both cause problems. The absence of sweat can be dangerous because your risk of overheating increases. Excessive sweating may be more psychologically damaging than physically damaging.

Hyperhidrosis is a condition of excessive sweating from the underarms, hands, and feet. This can be embarrassing and may stop people from going about their daily routines. Primary hyperhidrosis is the most common type and is not associated with a systemic disorder. Men and women are affected equally and most will have a family history.

Management of primary hyperhidrosis starts with topical antiperspirants. The main active ingredient in these is aluminium salts, which deposit within and temporarily block the sweat duct. There is a myth that has been circulating around aluminium in antiperspirants being absorbed into the skin and stopping toxins from leaving the body, resulting in breast cancer. A scientific review in 2016 found there was no link between antiperspirant/deodorant use and the risk of getting breast cancer.1

Other treatment options for hyperhidrosis include prescription tablets, iontophoresis, botulinum toxin injections, and surgery.

Botulinum toxin injections are a safe, quick, and effective way to manage hyperhidrosis affecting the underarms. Tiny needles are used to inject the substance into a grid on each armpit. Most patients remain sweat free for approx. 3-6 months post-treatment.

1.     Allam, M. Breast cancer and deodorants/antiperspirants: a systematic review. Central European Journal of Public Health. 2016; 24(3), 245-7.