The use of adrenaline autoinjectors is generally contraindicated in children weighing less than 15kg. However, their use may be beneficial in life-threatening situations. Here we report the case of a 2-year-old boy who weighed less than 15kg and had a history of 3 episodes of milk-induced anaphylaxis. He was prescribed an adrenaline autoinjector following parental consent. The boy experienced coughing, hives, dyspnea, hoarseness, and reduced consciousness after accidentally consuming dairy products during a family trip. His mother used the adrenaline autoinjector because the family was far from an emergency hospital. The patient’s condition was resolved and he was subsequently transported by ambulance to an emergency center and hospitalized. An antihistamine and a corticosteroid were administered to treat a persistent localized hives. No biphasic reaction was observed, and he was discharged the next day in good condition. An adrenaline autoinjector was effective for the emergency treatment of anaphylaxis in a child weighing less than 15kg. It is important to report such cases to accumulate and provide more information on the utility of adrenaline autoinjectors in children.