Anaphylactic shock is a life-threatening condition that occurs due to systemic vasodilation caused by mediators released from mast cells. Peripheral resistance is lowered and the arteriovenous pressure difference is lost. Generally, it is an IgE-mediated reaction, but there are other immunological and non-immunological mechanisms that can lead to anaphylaxis. Allergens that cause an anaphylactic reaction are most often food, drugs and insect venoms. Signs and symptoms of anaphylaxis usually appear within one to two hours after exposure to the allergen. In up to two thirds of cases the cause is unknown and anaphylaxis is idiopathic. Diagnosis is made using guidelines based on clinical criteria. Severe grade of allergic reaction is considered anaphylaxis. In the acute treatment of a patient with anaphylaxis and anaphylactic shock, it is necessary to manage the airway, administer intravenous saline solution and administer adrenaline. Adrenaline is the first line of therapy for anaphylaxis and it is given by intramuscular injection in the thigh muscle. It is administered in a dose of 0.3-0.5 mL and in a concentration of 1:1000. The use of an adrenaline auto-injector is recommended, and patients with a history of anaphylaxis must always carry an adrenaline auto-injector with them and know how to apply it. After an acute anaphylactic reaction, patients should be observed, as a biphasic reaction may occur. Patients are advised to avoid allergens. Allergen-specific immunotherapy is a treatment for allergies. The goal of immunotherapy is allergen tolerance.