Final answer:
The most commonly reported adverse effects of penicillin are hypersensitivity reactions, including contact dermatitis and life-threatening anaphylaxis.
Step-by-step explanation:
The most commonly reported adverse effects of penicillin are hypersensitivity reactions. Hypersensitivity to penicillin can manifest in several ways, with Type I hypersensitivity being the most severe. The allergic reactions to penicillin can range from mild skin rashes, such as contact dermatitis, to more severe systemic responses like anaphylaxis, which is life-threatening.
Type I hypersensitivity reactions can be either localized, including symptoms like hay fever rhinitis, hives, and asthma, or systemic, known as anaphylaxis or anaphylactic shock. Anaphylaxis is characterized by sudden swelling of the tongue and trachea, blockage of airways, dangerous drops in blood pressure, and potential shock, leading to death in minutes if untreated. Due to the risk of anaphylaxis, caution is always advised when administering penicillin, and alternative antibiotics should be used for individuals with known allergies.