Allergy is an abnormal immune response that is related to genetic constitution and influenced by environmental factors What are the common clinical manifestations of allergy? One of the most common allergic diseases is allergic rhinitis, with an incidence of 20-40%, which is characterized by paroxysmal sneezing, runny nose, nasal itching and nasal congestion. Allergic rhinitis is divided into seasonal and perennial. Seasonal allergic rhinitis is often caused by spring tree pollen such as poplar, willow and elm and autumn pollen such as artemisia, grass and ragweed; the most common allergens of perennial allergic rhinitis are house dust and dust mites. Untreated allergic rhinitis can cause sinusitis, otitis media and other comorbidities, and half of the rhinitis patients with summer and fall pollen allergy are likely to develop allergic asthma within 9 years. Allergic rhinitis is often accompanied by conjunctivitis symptoms such as itchy eyes, red eyes and tearing, also known as allergic rhinoconjunctivitis; when allergy involves the tracheobronchial tubes, patients experience recurrent dry cough and even life-threatening wheezing; when skin and mucous membranes are involved, hives and angioedema appear; when the digestive system is involved, abdominal pain, diarrhea and large amounts of fluid in the abdominal cavity are easily misdiagnosed as acute abdomen; when the cardiovascular system is involved, patients experience blood pressure When the cardiovascular system is involved, the patient may experience a drop in blood pressure, loss of consciousness to anaphylaxis or even death. Allergy can also cause vertigo, and our department has found several cases of facial paralysis related to allergy. What are the common characteristics of allergic diseases? Most of them have a clear cause or trigger. For example, drug allergy has a history of drug application, and hair dye allergic dermatitis has a clear history of hair dye application. Symptoms come and go quickly. Allergic reactions often occur rapidly and progress rapidly to a peak within a few minutes to a few hours, and resolve quickly after the cause is removed. In addition, it should be noted that allergic diseases often have atypical manifestations, such as chronic dry cough, diarrhea, dizziness, mouth ulcers and other symptoms that persist and recur despite symptomatic treatment in the relevant departments, which can be checked for food or other allergic factors.