What are the symptoms of allergic reaction?

Allergy, the common symptom of allergic diseases, is also called allergic reaction, which is a pathological process that is unfavorable to the body caused by abnormal immune mechanism. Common allergic diseases include allergic rhinitis, bronchial asthma, eczema, urticaria, food allergy, drug allergy, insect bite allergy and anaphylactic shock. Babies with allergic rhinitis often rub their noses, shed tears, sneeze, and have a stuffy nose, which affects their sleep. Severe cases may be complicated with acute and chronic sinusitis, recurrent otitis media with hearing loss, eustachian tube dysfunction, language retardation, nasal polyps, sleep apnea, and may develop into asthma. Asthma Asthma is the most common chronic disease in children, and more than 80% of children's asthma is caused by allergies. Nearly12 asthmatic children have symptoms such as cough, asthma and dyspnea before the age of 3. Allergic cough, a variant of asthma, is characterized by chronic cough, which is often regarded by parents as respiratory infection. Eczema, commonly known as tinea lactis, usually occurs about 40 days after birth. The typical rash of acute attack is erythema and itching, and the epidermis falls off after scratching. In severe cases, blisters may appear with serous exudation, and the secondary infection is pustule. If it is not controlled, it will become chronic: the skin becomes thicker, moss grows, and pigmentation occurs. It may also be complicated with recurrent keratoconjunctivitis, otitis externa and skin infection. Anaphylactic shock is often caused by drug allergy, food allergy or insect bite. It is caused by the sudden release of a large number of mediators by mast cells under the attack of allergens, the most important of which is histamine, which can cause a sudden drop in blood pressure and insufficient blood supply to various organs, thus affecting the functions of various organs. If not rescued in time, it will lead to death. Food allergy is an abnormal reaction of the immune system caused by eating certain foods. In addition to anaphylactic shock, asthma, urticaria and eczema, babies with food allergies often have symptoms such as nausea, vomiting, diarrhea, abdominal pain, dysphagia and weight loss. The health of allergic babies has a development process, that is, with the growth of the baby's age, the manifestations of allergic diseases will change in stages and different allergic symptoms will appear. Generally speaking, within one year old, the baby is mainly manifested as food allergy; Asthma can occur around the age of three; /kloc-After 0/0 years old, allergic rhinitis and asthma are the main manifestations. Therefore, early detection of allergies and active measures can reduce the risk of other allergic diseases in the future. Scientific diagnosis and treatment to control the disease must first carry out allergen testing for babies suspected of allergic diseases.