BMJ Group Medical Reference
This information is for people who have eczema. It tells you about antihistamines, a treatment used for eczema.
Do they work?
We haven't looked at the research on antihistamines in the same detail we have the other treatments for eczema. (For more information, see Our method.) But we've included some information because you may be interested in this treatment.
What are they?
Your doctor may prescribe a drug called an antihistamine for you or your child, if the itching is making it very hard for you to sleep. But doctors are advised only to use antihistamines for a short time. The idea is that antihistamines may relieve the itching caused by eczema.  Antihistamines are often used to treat allergic skin rashes, insect bites, and stings. But doctors don't know for sure how well antihistamines relieve the itching in eczema.
How can they help?
There are two types of antihistamine: one kind makes you sleepy (sedating antihistamines) and the other doesn't. Some doctors think only the kind that makes you sleepy can help with eczema. They say it only works because it helps patients get a good night's rest. Plus, when you're asleep, you don't scratch, and that keeps the symptoms from getting worse. 
We found one big summary of research that looked at more than 20 studies where people with eczema took antihistamines.  None of the studies showed clear evidence that the antihistamines that make you sleepy help relieve the symptoms of eczema. In fact, the review found that there is very little evidence that any kind of antihistamine works in eczema.
Doctors who treat eczema are interested in a group of drugs called 'mast cell stabilisers'. Like antihistamines, mast cell stabilisers are used to treat allergies like hay fever. An example of this kind of drug is sodium cromoglicate (the brand name for the capsule form is Nalcrom). Doctors thought that sodium cromoglicate might help relieve the symptoms of eczema. But so far, the research hasn't shown any clear evidence that cromoglicate is a good treatment for eczema. 
Can they be harmful?
The review didn't talk about the side effects that people got when they took antihistamines for eczema. But we know that antihistamines can cause side effects when you take them for other conditions, especially drowsiness. You shouldn't drive or operate machinery if you are taking an antihistamine that makes you drowsy.  An antihistamine called promethazine can cause dangerous breathing problems in very young children.  It isn't recommended for children under 2. 
For references related to Eczema click here