Final answer:
Allergic reactions to injected medications may occur immediately and are potentially life-threatening, with anaphylaxis being one of the most severe reactions. Epinephrine is typically used to treat such reactions, and desensitization therapy can help to prevent them.
Step-by-step explanation:
Allergic reactions to injected medications may occur immediately and may be quite severe. Among the most dangerous reactions is anaphylaxis, a rapid systemic response that can lead to life-threatening symptoms such as swelling of the throat, severe reduction in blood pressure, and a blocked airway, which can be fatal if untreated. The standard emergency treatment for anaphylaxis is the administration of epinephrine, which can quickly counteract these effects by raising blood pressure and relaxing bronchial smooth muscle to improve breathing. Patients known to have severe allergies often carry an auto-injector of epinephrine (e.g., EpiPen®) for self-administration in case of an allergic emergency, ensuring they can manage the reaction until they are able to reach medical support.
While mild allergic reactions are commonly treated with antihistamines, desensitization therapy is also a preventative measure that can be applied over a long term. This involves the injection of gradually increasing doses of the allergen, with the aim of reducing the severity of the immune response; however, this treatment must be administered with caution as it can still trigger a severe reaction.