RCT to Investigate if Prophylactic Antibiotics Prevent Further Episodes of Cellulitis (Erysipelas) of the Leg

Inclusion Criteria: * Diagnosis of cellulitis of either leg AND a history of at least one previous episode of cellulitis of either leg within the three Exclusion Criteria: Any doubt about the certainty of the diagnosis of either the index episode or the previous episode (if applicable), will be grounds for exclusion. Additionally, patients with any of the following will be excluded: * Taken antibiotic prophylaxis (defined as more than 3 months usage) for the prevention of cellulitis within 6 months prior to index episode. * A time lapse of longer than 12 weeks since the start of treatment for the index episode to the date of potential randomisation into the trial. * Known allergy to penicillin. * Preceding leg ulceration, surgery or penetrating trauma, as these cases are more likely to be caused by staphylococcal infection. (NB: this does not exclude patients with toeweb maceration/tinea pedis or other minor/blunt wounds). * Treating physician or principal investigator unwilling to randomise patient. This includes, but is not limited to: * The treating physician and/or patient feels that prophylactic antibiotics are not in the patient's best interests and therefore entry to this study would be inappropriate. * The treating physician and/or patient feels it would not be ethical or appropriate for the patient to receive placebo and so they are not willing/able to accept randomisation * Concomitant medication that would mean that long-term penicillin is inappropriate …