What is a common allergic reaction associated with penicillin use?

A common allergic reaction associated with penicillin use is an itchy rash. This reaction is typically characterized by hives or urticaria, which can appear as red, raised, and itchy spots on the skin. The itchiness is a symptom of the body’s immune response to the penicillin, which is mistaken for a harmful substance. This type of skin reaction can be quite common and is usually not severe, though it may indicate a penicillin allergy.

While other reactions such as facial swelling can also occur and may indicate a more severe allergic response, the itchy rash is often the first sign of a penicillin allergy and is more commonly reported. Nausea is not an allergic reaction; rather, it may be a side effect of the medication or an unrelated gastrointestinal issue. Additionally, an arm rash specifically is not a typical designation for penicillin reactions; the rash can occur on various parts of the body and is not localized to just one area. Thus, the itchy rash is the best representation of a common allergic reaction to penicillin.