Before starting therapy with Ampicillin, caution should be taken on previous hypersensitivity reactions to beta-lactam antibiotics. Serious and even fatal hypersensitivity reactions can occur in individuals with a history of beta-lactam hypersensitivity.

Ampicillin should be avoided if there is suspicion of infectious mononucleosis and/or acute or chronic leukaemia of lymphoid origin. The occurrence of a skin rash can occur with these conditions following the administration of Ampicillin. Prolonged use may occasionally result in overgrowth of non-susceptible organisms.