Antibiotics do not help patients with an uncomplicated common cold. Antibiotics can have side effects for the individual taking them that range from unpleasant to serious, even lethal. Antibiotic use also contributes to communal harm by encouraging antibiotic resistance. If there can be no benefit, but there can be harm, why is the common cold the commonest reason for doctors to prescribe antibiotics? We note that antibiotics are also overused in other conditions and other medical disciplines, as well as in agriculture and the food industry. The harm caused by antibiotics ranges from mild gastrointestinal disturbance to death. Reasons for overuse of antibiotics to treat the common cold include patient expectations, patient and doctor uncertainty around diagnosing complications of the common cold, and the pressure on the doctor to ‘do something doctor — anything’. Strategies to limit inappropriate antibiotic use are explored, particularly the use of ‘delayed prescriptions’, and evidence is presented that with education of doctors and patients the overuse can be reduced.