In this review, we discuss anaphylaxis, which is a severe allergic condition with potentially life-threatening symptoms from airways or circulation and often associated with skin symptoms. First-line treatment is intramuscular adrenaline given by autoinjector for rapid administration. Initial dose for children less than 25 kg is 0.15 mg and for children ≥ 25 kg and adults 0.3 mg. Repeated smaller doses of adrenaline is to be preferred. Patients with severe anaphylaxis will need an IV access for fluid replacement and supplementary oxygen. Antihistamines and steroids are only second-line treatment after adrenaline administration.