Allergic reactions are the responses of the immune system to an allergen, normally a harmless substance from the environment, that causes cell damage. Allergic reactions have specific and easily recognizable symptoms. They can sometimes be life-threatening and should be prevented from further progression. This is where emergency medicine plays a major role. Treating an acute allergic reaction or an anaphylactic shock is challenging for the prehospital emergency medical service. A generalized allergic reaction which progresses to an anaphylactic shock is a severe condition that requires an experienced team that will be able to treat it promptly and successfully. Anyone can have an allergic reaction at any time. The most common causes are insect stings or the inhalation of an allergen. The treatment depends on the individual patient and the severity of the reaction. The role of nurses in the treatment of allergic reactions is very important. The nurses that take part in the treatment of patients with allergic reactions should be competent to quickly respond in symptom management and have excellent manual skills in finding and obtaining venous access. The importance of a well established team of the prehospital emergency medical service should also be emphasized.