Relatively infrequent and generally mild and transient. The most frequent are local reactions following IM or IV injection. IV injection may cause phlebitis; this can be avoided by slow injection (3-5 min). IM injection may cause transient pain at the site of injection, especially with higher doses; this can be avoided by addition of lignocaine.
Next in frequency are hypersensitivity reactions (rash, pruritus, fever) and gastrointestinal (colitis, diarrhea, nausea, vomiting).
Less frequent adverse reactions include transient leukopenia, eosinophilia and neutropenia; transient elevations in SGOT, SGPT, serum alkaline phosphatase and BUN; headache; moniliasis and vaginitis.
Anaphylactic shock is extremely rare, but it is a conceivable risk. If it occurs, generally within 30 min of drug administration.