Increases potential for ampicillin-induced skin rash. If a skin rash develops, consider discontinuing one or both drugs.
May reduce efficacy of oral contraceptives. Use of alternative methods of contraception is advisable.
Ampicillin/sulbactam may decrease the effectiveness of live vaccines. Use of live vaccines with ampicillin/sulbactam is not recommended.
Methotrexate plasma concentrations may be elevated, increasing the risk of toxicity. Monitor patients for methotrexate toxicity and measure methotrexate concentrations. The dose and duration of leucovorin rescue may need to be increased. Consider use of alternative antibiotic treatment.
Renal tubular secretion of ampicillin and sulbactam may be decreased, resulting in increased and prolonged levels of ampicillin and sulbactam. It may be necessary to administer ampicillin/sulbactam less frequently when probenecid is coadministered.
May impair bactericidal effects of ampicillin/sulbactam. If possible, avoid coadministration of these agents.
The risk of bleeding may be increased, especially with large IV doses of ampicillin. Monitor coagulation status and adjust the warfarin dose as needed.