Itching, also known as pruritus, can be one of the most distressing physical sensations we experience. It is also very hard to describe. The best definition of itch is probably ‘a sensation that makes you want to scratch’.
Most of the time, itching is a short-term problem and its cause will be obvious. The red swelling of a mosquito bite, or other insect bite or sting, is easy to see and may cause intense itching for a limited time.
People whose itch is due to eczema or allergic contact dermatitis usually have an easily recognisable rash in the affected area. They will experience recurrent attacks of itching when their problem flares up, but will usually have learnt how to control it with the use of creams or ointments.
When the sensation of itching is present without a rash or other visible cause it can sometimes be hard to find the reason. In turn, this may make treatment difficult.
Causes of itching
There are a number of possible causes for an ‘unexplainable’ itch. These include the following.
- Age. Roughly half of those over the age of 70 will experience itching, and may damage their skin by excessive scratching. With age, our skin becomes much drier and regular use of moisturisers will usually solve the problem.
- Hormonal changes after the menopause. Many women at this stage of their lives experience itching, often associated with hot flushes, which are worse at night. Hormone replacement can produce a rapid improvement.
- Changes in body chemistry. Most people having dialysis (artificial kidney) treatment get pruritus, although the reason for this is not certain. People with jaundice, in which the amount of bile salts in the circulation is abnormally high, usually get itching.
- Reaction to water. Some people seem to develop an itch when their skin is in contact with water, regardless of its temperature. This is difficult to treat but may respond to treatment with ultraviolet (UV) light.
- Illness. Certain illnesses such as thyroid disease and some blood disorders may cause generalised itching. Some types of cancer may also produce itching.
- Psychological causes. Stress and anxiety may produce itching. Sometimes people with delusions (false beliefs) may think they have parasites on their bodies and be convinced that they are making them itch.
If you get recurring feelings of itching and can't see a cause, discuss it with your doctor. It is possibly a warning of some other problem and can usually be relieved.
Last Reviewed: 02 December 2009
- 1. Itch without rash [revised February 2009]. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited; 2009 Nov (Accessed 2009 Dec 4.) http://www.tg.org.au/