A drug rash may be either a side effect of a drug or an allergic reaction to a medication. While any medication may cause a drug rash, common culprits include antibiotics, anti-seizure medications and water pills (diuretics). Some drugs are more likely to produce a rash if the skin is exposed to sunlight.
A drug rash, which usually starts within the first week of taking a new medication, often begins as discrete red spots that spread, covering large areas of the body. The rash usually resolves in days to weeks after discontinuing the medication.
A drug rash can rarely be part of a more serious, potentially life-threatening allergic reaction that affects the respiratory system and other organs. These severe reactions require emergency care.