These drugs include: aspirin, phenylbutazone, sulfonamides, indomethacin, thiazide diuretics, furosemide and ethacrynic acid.
Source: FDA drug label - penicillin g sodium
Penicillin G Sodium Interactions
Brand names: Penicillin G Sodium
2 interactions on record
Drug Interactions Bacteriostatic antibacterials (i.e., chloramphenicol, erythromycins, sulfonamides or tetracyclines) may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided. Penicillin blood levels may be prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins. Other drugs may compete with Penicillin G for renal tubular secretion and thus prolong the serum half-life of penicillin.
Source: FDA drug label - penicillin g sodium