ITCHING - Full extract 

Itching or pruritus is a common problem. Having a slight itch is of little concern, but being very itchy is another matter altogether. Severe itching and scratching is an extremely distressing symptom for people of any age. 

Between the upper two layers of the skin are nerve endings that are sensitive to various chemical substances like histamine. With an insect bite or some plant rubbing against the skin, histamine is released from mast-cells in the skin and the local nerve endings are stimulated. Impulses pass along sensory nerves to the spinal cord and then up to the brain; the person's level of consciousness is reached and the itch is felt. The sensation may be modified to some extent depending on how we feel; if we are relaxed the sensation may be dampened, if we are stressed it may be greatly amplified. 

Localized itching can be due to many causes. Bites and hives can cause intense local reaction in the skin, at times so severe that welts may appear. These might appear on areas like the forearms after gardening. Contact dermatitis on the hands often occurs when working with soil or cement. Similar irritations may occur from contact with nickel-containing jewellery. Vulval itch occurs with vaginal infections like thrush and requires specific treatment. Anal itching is also common and can be equally distracting; it may be due to haemorrhoids but usually no specific cause is found. Eczema and psoriasis are complex conditions that can cause local or generalized itching with distinctive rashes. 

Generalized itching can also be due to a variety of causes and may be more upsetting for the patient than a local itch. Allergies are always high on the list and the offending stimulus can be anything animal, vegetable or mineral. It may even be due to a medication that the person is taking. Infections can cause a generalized itch, especially conditions like chickenpox. Parasitic infections like scabies should also be considered. A number of underlying medical conditions can get people scratching. Liver and kidney disease, and certain blood disorders can all cause generalized itching. Sometimes even pregnancy will do it. 

The treatment of itching depends on the actual cause. A history dealing with general health and possible exposure to irritating agents is important. A careful physical examination is performed, often including a test of the urine. Occasionally blood tests and other investigations are also required. 

Anything that could be making the skin more itchy should be avoided, especially rough woollen materials against the skin. 

Repeated scratching should also be resisted as it frequently sets off a scratch-itch cycle. A variety of topical preparations like calamine lotion are available, but these can sometimes cause excessive drying of the skin. If an itching skin condition is being aggravated by emotional stress, this may require treatment as well. 

If the skin is dry, bath oils and other emollients can help by putting moisture back into the skin; this often produces great improvement in older patients with itchy skin. When the skin is acutely inflamed, cortisone creams are often very effective. However, they should only be used on the advice of your doctor, usually on a decreasing scale and for a specified period. When itching is very distressing, a course of oral medications such as non-sedating antihistamines may be necessary. Sometimes itches that do not settle require referral to a dermatologist. 

Health tips: 
* Avoid mixing and matching creams; what has been prescribed for one condition may make another condition worse. 

* The cause of itching may not always be obvious. Any persistent itch is worth discussing with your doctor.

Dr. Andrew Pattison: Common Consultations
North East Valley Division General Practice, Melbourne, Australia.   Disclaimer
  - Last modified: August 18, 2001