Penicillin G Interactions

These drugs include: aspirin, phenylbutazone, sulfonamides, indomethacin, thiazide diuretics, furosemide and ethacrynic acid.

Source: FDA drug label - penicillin g

, 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

Bacteriostatic antibiotics: Bacteriostatic antibiotics, such as tetracycline, erythromycin and chloramphenicol, may antagonize the bactericidal effect of benzylpenicillin by interfering with active bacterial growth necessary to benzylpenicillin’s effect. Oral contraceptives: The efficacy of oral contraceptives may be impaired in case of concomitant therapy with benzylpenicillin, which may result in an unwanted pregnancy. Probenecid: Probenecid decreases the renal tubular secretion of benzylpenicillin.

Source: FDA drug label - penicillin g benzathin