Are there official recommendations for treating erythema multiforme?

Try these: Find british guidelines here: http://bestpractice.Bmj.Com/best-practice/monograph/367.Html. I'm not certain that their official guidelines. Not aware of american guidelines for treating this self-limited disease.

Evaluate cause: Ruling out possible immunologic causes, including autoimmune, infection, or allergic reactions is first step, before initiating therapy such as prednisone.

See a dermatologist: Most em is erythema multiforme minor due to herpes. Every time you get a recurrence of a cold sore or other herpes you take a dose of Acyclovir pills or valacyclovir. This will prevent em. Erythema major can be serious , is most often an allergy to sulfonamide (smz/tmp) but may have numerous other causes. Treatment can be difficult , especially regarding the eyes.