Author: Dr Mark Duffill, Hamilton, New Zealand, 2008. Reviewed and updated by Chief Editor, Hon A/Prof Amanda Oakley, July 2015.
Symmetrical drug related intertriginous and flexural exanthema (SDRIFE) describes a distinctive erythematous rash which occurs in skin folds after systemic exposure to a food or drug.
The substance may be taken orally, given by injection, or absorbed by some other route resulting in a general exposure of the body,
It is also called baboon syndrome when the predominantly affected area is the buttocks, as was the case in the first patients to be described with the reaction.
The clinical picture of SDRIFE is of a well-defined redness of the buttocks, natal cleft and / or upper inner thighs resembling the red bottom of baboons. The redness often forms a V-shape. The neck, armpits and other skin folds may be involved, usually symmetrically but sometimes only on one side. The affected person is not unwell and the rash is not accompanied by any other symptoms.
In classical SDRIFE, the initial sensitization is by skin contact with the causative agent then a rash with the particular appearance of the baboon syndrome is brought out by taking the agent by mouth (systemic contact dermatitis). It is not fully understood why the rash should occur in these particular areas.
Classical baboon syndrome was originally observed with mercury, nickel and ampicillin.
Since then over 100 cases of SDRIFE have been described, most of them without known prior sensitisation to the causative agent. At least 50 causative medications have been reported to cause SDRIFE, including prescribed and over-the-counter products. Amoxicillin and other beta lactam antibiotics account for about half of cases. Diverse other causative drugs have included pseudoephedrine, codeine, allopurinol, cimetidine and nystatin.
Patch tests may be performed several weeks after the patient has recovered from SDRIFE, and may show a positive reaction to the suspected causative agent. An oral “challenge” to the suspect may be given.
Skin biopsy of affected skin may reveal mixed superficial perivascular inflammation.
The most important treatment in SDRIFE is to identify and stop the causative agent. The patient should be advised to avoid the causative medication lifelong. Topical steroids may reduce the redness while the reaction resolves.
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