Drug Allergy

The more serious allergic reaction is called anaphylaxis, which can lead to anaphylactic shock and be fatal if left untreated. Milder allergic reactions may be treated with antihistamines, bronchodilators or corticosteriods. Anaphylaxis often requires an injection of epinephrine.

This is not to be confused with an adverse reaction to a drug that does not involve the immune system, such as "side effects," tolerance issues, over- or under-dosing, and contraindications with other medications. Up to 95% of drug reactions are not allergic reactions.