Interactions of Cranberry Juice & Amoxicillin

Cranberry juice is frequently recommended in cases of urinary tract infection 1. But case reports indicate that the juice may alter the metabolism of certain medications. The popular antibiotic amoxicillin, however, is not one of them 2. Research indicates cranberry juice does not hamper the effectiveness of amoxicillin 12.


Amoxicillin is a synthetic penicillin 2. It is used to treat various bacterial infections such as ear infections, bladder infections, pneumonia, gonorrhea or E. coli. You should not take amoxicillin if you are allergic to penicillin or other penicillin-based antibiotics 2. Like other antibiotics, it is important that you take the entire dose as prescribed by your doctor to clear up the infection. Amoxicillin may cause diarrhea 2. If your diarrhea is bloody, stop taking your amoxicillin and contact your doctor immediately 2.

Cranberry Juice

Cranberry juice is an antioxidant-rich juice that may help prevent urinary tract infections 1. It also may help lower your risk of heart disease and aid in cancer treatment. A 1-cup serving of unsweetened cranberry juice contains 116 calories, 1 g of protein, 0 g of fat and 30 g of carbohydrates 15. It also contains 24 mg of vitamin C, 114 IU of vitamin A and 3 mg of vitamin E. These substances protect your cells against oxidation.

Amoxicillin and Cranberry Juice

Because cranberry juice is recommended as part of the treatment plan for a urinary tract infection, researchers investigated whether cranberry juice interacts negatively with amoxicillin 12. In a 2008 study, scientists at the University of Washington tested the effects of cranberry juice on amoxicillin metabolism in 18 women volunteers 12. The subjects were given two doses of amoxicillin -- 500 mg and 2 g -- with or without an 8 oz 2. serving of cranberry juice 135. At the conclusion of the study, the researchers saw no change in absorption or renal clearance of the amoxicillin in the participants given the cranberry juice 12.


Although it does not appear to hamper amoxicillin, cranberry juice is highly acidic 12. Such foods can interfere with the absorption of some medications, and physicians have recommended that patients avoid acidic foods at the time they take their drugs. As a rule, always talk to your doctor or pharmacist about potential drug and food interactions.