The following adverse reactions have been reported with parenteral penicillin G (the active moiety in Penicillin G Procaine)
Penicillin is a substance of low toxicity but does possess a significant index of sensitization. The following hypersensitivity reactions associated with use of penicillin have been reported: Skin rashes, ranging from maculopapular eruptions to exfoliative dermatitis; urticaria; serum-sickness like reactions, including chills, fever, edema, arthralgia, and prostration. Severe and often fatal anaphylaxis has been reported: severe cutaneous adverse reactions (SCAR), such as toxic epidermal necrolysis (TEN) and acute generalized exanthematous pustulosis (AGEP) (see WARNINGS). As with other treatments for syphilis, the Jarisch-Herxheimer reaction has been reported.
The following adverse events have been temporally associated with parenteral administration of Penicillin G Procaine (a component of Penicillin G Procaine)
Pseudomembranous colitis has been reported with the use of penicillin G. Onset of pseudomembranous colitis symptoms may occur during or after antibiotic treatment (see WARNINGS).