Overview
In Fixed Drug Eruption (FDE), single or multiple round to oval-shaped dark reddish patches develop in the same site or sites each time a particular drug is taken.
Sometimes, there may be swelling, blistering or erosions in the affected areas. The lips or genitalia can occasionally be the only site of involvement in FDE. FDE usually occurs between 30 minutes to 8 hours after ingesting the culprit drug.
Causes
There are many medications which can cause FDE, eg. tetracycline antibiotics.
Prevention
What is a drug provocation test?
A drug provocation test is the controlled administration of a drug to diagnose an immune-mediated and non–immune-mediated drug reaction. It is usually done under medical supervision. Drug provocation test has the potential risk of inducing a more severe and uncontrollable relapse of the original reaction. It is therefore a test which should be reserved for specific situations and when the benefits outweigh the risks.
Detection & Treatment
Evaluating drug allergies/ cutaneous adverse drug reactions can be challenging. An accurate, detailed history and clinical examination will help to establish the type of CADR and to identify the culprit drug. Blood tests, skin biopsies and skin tests (eg. Skin prick tests, intradermal tests and patch tests) are sometimes needed in the evaluation, but the usefulness of these tests is dependent on the type of the reaction and the drugs involved.
Not all cases of drug allergies/ cutaneous adverse drug reactions require specific drug allergy testing and not every medication or type of CADR has a blood test or skin test to help in the diagnosis.
The redness in FDE subsides with cessation of the culprit drug, but the dark patches can be persistent.
Specialties & Services
