Penicillin group of antibiotics are still a popular choice for various infections. These antibiotics are relatively non-toxic except for the fact that risk of hypersensivity exists. Penicillin on degradation produces penicilloic acid and others which serve as antigenic determinants either themselves or after being bound to host proteins.

Allergic reactions after penicillin administration:



Joint Swelling

Angioneurotic edema

Intense pruritus

Breathing difficulty

Skin rashes

Oral lesion

Interstitial nephritis


Hemolytic anaemia


Anaphylactic shock

Adverse effects to specific forms of penicillin:

In patients with renal failure, high doses of penicillin causes seizures. Nafcillin is associated with Neutropenia, Oxacillin with neutropenia, methicillin with interstitial hepatitis

High oral dosage leads to gastrointestinal upset, pseudomembranous colitis. Prolonged usage can predispose to secondary opportunistic infections like candidiasis – vaginal or oral.

Ampicillin and amoxicillin, the most commonly used preparations are notable in causing skin rashes as adverse effects. Contradictory to popular belief, these reactions are non allergic in nature.

Penicillin Images: