Health Information and Self Care Advice for Scotland

Nettle rash

Introduction

Nettle rash (also known as hives or urticaria) is characterised by a lumpy, itchy rash with red spots. It is the rash you get when you have been stung by nettles. However, it can also be caused by a reaction to certain foods and occasionally, by a viral infection.

If the rash lasts less than six weeks it is called acute urticaria. Acute urticaria usually clears up within 24 hours. Very occasionally, a persistent form called chronic urticaria, develops which lasts for several months or even years and the rash keeps coming and going on most days for more than six weeks.

Acute urticaria is common. Approximately 20% of people will have at least one attack of urticaria in their lifetime. Chronic urticaria is much less common; approximately 1 in 1000 people develops chronic urticaria in their lifetime.

 Sometimes, urticaria occurs at the same time as the more serious condition called angioedema. Angioedema involves swelling in the deeper layers of the skin. The swelling causes a burning sensation and often occurs on the neck and face, the fingers and toes, and, in men, the genitals.

The lining or the mouth and windpipe may swell and breathing may become difficult. Angioedema occurs in approximately half of people with chronic urticaria, it also occurs without urticaria and with acute urticaria. Angioedema commonly lasts 1-2 days and occurs from time to time. Occasionally the tongue or throat swells, this is rarely life-threatening unless it is associated with a serious food allergy.

Acute urticaria is also one of the symptoms of a serious allergic reaction affecting the whole body. This is called anaphylaxis and can happen within minutes to hours of exposure to the substance that the person is allergic to. Other symptoms of anaphylaxis include shock, swelling all over the body, wheezing and abdominal cramps. Anaphalaxis can be life threatening so should be treated as a medical emergency.
.

Incidence rates for acute urticaria are similar for men and women; chronic urticaria occurs more frequently in women.

Last updated on 27 June 2007 04:48 PM