The outlook for most rashes is excellent, especially after the cause has been identified accurately.
In severe allergic reactions, a patient can die within minutes without immediate medical treatment. With proper treatment, recovery usually is complete. However, the patient remains at risk of future severe reactions if he or she is exposed to the same allergy-producing agent. For this reason, a prescription for a self-injection pen containing epinephrine for emergencies usually is recommended for people with severe allergies.
For long-term autoimmune conditions, rash is only one of a wide variety of symptoms. The prognosis depends on the type and severity of the autoimmune disease.