10 February 2020 What is anaphylaxis and what are its signs and symptoms? Anaphylaxis is the most serious form of an allergic reaction . It can be presented by breathing difficulties, loss of consciousness or even death if it is not treated immediately. Anaphylaxis requires immediate medical treatment and requires further evaluation by an immunoallergology specialist. Anaphylaxis symptoms progress quickly, usually in a few minutes, and may include: Skin and mucous membranes : itching, erythema (redness), papules, edema (swelling); Eyes : itching, watery eyes, erythema; Nose and mouth : sneezing, nose discharge, nasal obstruction, tongue edema; Throat and lungs : breathing difficulty, coughing, tightness in the chest, wheezing, voice changes and choking sensation; Heart and circulatory system : dizziness, weakness, low blood pressure, irregular heart rhythm; Digestive system : nausea, vomiting, diarrhea and abdominal pain; Nervous system : anxiety, confusion, fainting. Who can have anaphylaxis? Anaphylaxis is unpredictable . It can occur in people with a previous diagnosis of allergy, but it can also be the first manifestation of allergy. Anaphylaxis can occur in anyone exposed to a substance to which they are allergic. The form of contact with this substance is diverse, as the causal agent can be: Injected , for example as with bee or wasp bites or medicines; Ingested , for example with medicines and food; Inhaled , for example with proteins evaporated during the cooking of some foods; Direct contact , for example with latex and some foods. The severity of an anaphylactic reaction can be minimized : By its quick recognition; By the use of appropriate drugs; By resorting to urgent medical care. What is the cause of anaphylaxis? Anaphylaxis can have several causes. The most frequent are: Food : cow milk, egg, fish, seafood, nuts, peanuts, fresh fruits (peach and other stone fruits) and seeds, including sesame; Drugs : antibiotics, especially beta-lactams (penicillins and cephalosporins), and non-steroidal anti-inflammatories (NSAID) are the drugs that most often can cause anaphylaxis. In this group radiological contrasts and drugs administered in a surgical context (for example, anesthetics, relaxants) are also included; Hymenoptera poison (bee, wasp): in most cases, the resulting sting is painful and only causes discomfort that can last for a few hours. However, in some people very serious reactions can occur; Latex and other occupational allergens : in latex allergy, severe reactions usually occur during surgery or when there is contact with the latex through the mucous membranes. In some people, anaphylaxis may occur following the ingestion of fruits (nuts, bananas, avocados, among others) and vegetables with cross reactivity with latex (latex-fruit syndrome); Physical agents : cold and physical exercise. In some cases, exercise can lead to anaphylaxis; sometimes, this situation only occurs if there is a previous intake of certain foods before exercise (food-dependent exercise-induced anaphylaxis). Some patients with cold urticaria can have severe manifestations, depending on the water temperature and the increased body surface area (for example, with diving in the sea or river); Idiopathic anaphylaxis : when it is not possible, after an exhaustive study, to identify any cause for an episode of anaphylaxis, it is called idiopathic anaphylaxis, which is thus an exclusion diagnosis. How is anaphylaxis diagnosed? The diagnosis of anaphylaxis is essentially clinical and based on: a detailed medical history ; in the pattern of symptoms that occur immediately (between minutes to approximately one hour) after exposure to the potential causative agent. Once the anaphylaxis has been resolved with immediate medical treatment, patients should go to an immunoallergology consultation . As part of this consultation, after a thorough clinical evaluation, complementary diagnostic tests may be requested, such as: skin tests; laboratory tests; provocation test with the agent involved to identify or confirm the cause of anaphylaxis. What should be done in case of anaphylaxis? If you have severe allergic symptoms you should be observed immediately by a doctor or go to an emergency service , where you can receive treatment with drugs used in these serious forms of disease, eg: adrenaline, antihistamines, corticosteroids, bronchodilators and oxygen. The anaphylactic reactions must be treated quickly. Early treatment is associated with less severe reactions. The treatment can be started at home (if there is a previous diagnosis), but the patient should be always evaluated in the hospital. If you have had an anaphylactic reaction, you should be observed by an immunoallergologist for correct guidance and determination of the exact cause of anaphylaxis. You must have an identification device (card, medical report, bracelet) that indicates your allergies, as well as a written emergency plan including an adrenaline self-injecting device (“pen”). The patient and their caregivers must learn to handle it correctly (intramuscular administration on the antero-lateral region of the thigh) and pay attention to the expiration date of the device. The authors of this text are the following allergologists from the Hospital da Luz network: Luís Miguel Borrego, Ana Morais Mendes, Ana Reis Ferreira, Andreia Ferrão, Carlos Braga, Cristina Lopes, Diana Pereira da Silva, Filipa Semedo, Isabel Costa Silva, João Gaspar Marques, Pedro Carreiro Martins, Marta Salgado, Nuno Sousa, Rosa Anita Fernandes, Susana Piedade The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
