4 known interactions • 1 major • 1 moderate • 2 minor
Always disclose all medications to your healthcare providers — prescription medicines, OTC medications, vitamins, and herbal supplements. This list may not include every possible interaction. Use our Medicine Interaction Checker to screen your complete medication list.
Potentially life-threatening or causing permanent damage. Avoid combination.
May worsen condition or require dose adjustment. Monitor closely.
Usually limited clinical effect. Manage with routine monitoring.
Methotrexate
Penicillins reduce renal tubular secretion of methotrexate, potentially causing methotrexate toxicity.
Management: Avoid combination; monitor methotrexate levels closely if concomitant use necessary.
Warfarin
Antibiotics can alter gut flora that produces vitamin K, potentially increasing INR. Also direct interaction reported.
Management: Monitor INR closely when starting or stopping amoxicillin in patients on warfarin.
Oral contraceptives
Theoretical reduction in contraceptive efficacy via gut flora alteration. Evidence is very weak.
Allopurinol
Concurrent use with allopurinol increases the frequency of rash (ampicillin/amoxicillin rash).
Always ask your pharmacist about potential interactions with food, alcohol, and supplements specific to Amoxicillin. Some medicines have significant interactions with grapefruit juice, high-fat meals, dairy products, or vitamin K-rich foods.