Erythema Multiforme

Erythema multiforme causes bull's-eye-like red patches on the skin. Often there is a mild fever, fatigue, and joint aches. It usually lasts about 1-4 weeks with a gradual recovery. Severe cases may require hospitalization to treat dehydration or internal bleeding. The cause of this condition may be an allergic or drug reaction, an infection, a bite or sting, pregnancy, or other medical condition. The most common cause is a herpes simplex (fever blister, cold sore) on the lips, groin or the buttocks.

Erythema multiforme is not a skin infection. Like hives, it is a reaction to something internal. In most cases the rash disappears after one week. The treatment includes avoiding the drug or substance that caused this allergic reaction. Antihistamines can be used to reduce itching and pain. In severe cases, oral cortisone medicine may be needed. If your erythema multiforme is triggered by a herpes infection, an anti-viral medicine taken by mouth will help.


  • Your rash worsens.

  • A high fever develops.

  • The rash starts to blister.

  • You have sores in your mouth.

  • You vomit repeatedly.

  • You pass bloody or dark stool.