<p>Prolongation of bleeding time and prothrombin time have been reported in some patients receiving Co-amoxiclav. In common with other broad-spectrum antibiotics, Co-amoxiclav may reduce the efficacy of oral contraceptives and patients should be warned accordingly. Concomitant use of allopurinol during treatment with amoxicillin can increase the likelihood of allergic skin reactions. There are no data on the concomitant use of Co-amoxiclav and allopurinol.</p>