Itchy rashes

By on June 8, 2011
One sometimes hears of people suffering from ‘hives’.  This is a colloquial word for urticaria, an itchy rash in the form of blotches or wheals which can appear on any  part of the body and disappear after a few hours, only to recur later. It is also known as ‘nettle rash’, since stinging nettles produce a similar eruption.  The rash consists of raised smooth areas, variable in size and shape.  They are red at the edges and pale in the centre, and very itchy.  

What is the cause?  It may be an allergic reaction to certain foods: typically nuts, strawberries, shellfish, or eggs.  However, many foods may be implicated, or dyes or other additives. Each time the person consumes an item containing the offending substance the rash appears and the connection is usually obvious.  Treatment, therefore, consists in avoidance.  Medical drugs may produce a similar reaction, especially penicillin and other antibiotics, as well as aspirin and codeine, but many different drugs may be responsible for this and other types of rashes.  Contact with the latex in rubber gloves may cause a similar reaction.  

There is also a ‘chronic’ form of the disorder, in which the rash comes and goes for  many weeks or months, often for no obvious reason.  It is more likely to happen in people with a personal or family history of atopy or who suffer from eczema, asthma, or hay fever.  It is frustrating to deal with since the cause is usually undiscoverable.  Blood tests and skin patch tests in general are not helpful. The  mainstay of treatment is to take antihistamines regularly to suppress the rash.  This may need to be continued for weeks or months. Modern antihistamines do not usually cause drowsiness, which was a problem with the older type.  

Another common cause of an itchy rash, especially in the humid summer moths, is the so-called heat rash, also known as prickly heat or by the medical word miliaria (Latin for millet).  This is due to blockage of the sweat glands from excessive sweating.  The rash shows many tiny raised bumps or blisters which are said to look like millet seeds, hence the name.  They are intensely itchy but otherwise not harmful.  Treatment consists in cooling the skin by staying in an air-conditioned environment.  Applying talcum powder is soothing for the rash and vitamin C has been said to be helpful. 

Dr Gabriel Symonds is the founder and director of the Tokyo British Clinic which  offers comprehensive medical services including treatment of skin disorders.
Tel: 03-5458-6099.

About Dr. Gabriel Symonds

Dr. Gabriel Symonds was the director of the Tokyo British Clinic. The clinic closed down in May 2014 after serving the expatriate community for 20+ years. Dr. Symonds has retired and the Tokyo British Clinic is now closed. Dr Symonds will continue to live in Tokyo and may be contacted by e-mail over any questions concerning medical records or related matters: He will be available from another address for: smoking cessation psychotherapy/counselling circumcision information Tel: (03) 5458-6099