Patients with cold have dryness and burning sensation in the nose or foreign body sensation and itchiness for a few hours or 1-2 days before the onset of cold, sometimes with chills and general discomfort. After that, nasal congestion appears in about 2-7 days, which gradually worsens, with frequent sneezing, clear watery nose, reduced sense of smell, occlusive nasal sound when speaking, and possible rhinorrhea; at the same time, systemic symptoms reach their peak, such as fever (mostly low fever), lethargy, loss of appetite, headache, etc. The nasal mucosa is diffusely congested and swollen, and the total nasal passage or nasal cavity floor is filled with watery or mucus-like secretions. Finally, clear nasal discharge decreases and gradually becomes mucopurulent, and systemic symptoms gradually decrease. If there is no complication, it will be cured in 7~10 days. In contrast, allergic rhinitis has no systemic symptoms such as fever, and is mainly characterized by nasal itching, paroxysmal sneezing, profuse watery nasal discharge and nasal congestion. Most patients feel itchy inside the nose. Some patients may have itchy eyes and conjunctival congestion, and itching in the external ear canal and soft palate. Sneezing, a reflex action. Several paroxysmal episodes of more than 3 or even 10 or more in a row occur several times a day. Mostly in the morning or at night or immediately after contact with allergens. Runny nose, with a large amount of clear watery nasal discharge, sometimes dripping unconsciously from the nostrils. Nasal congestion, varying in severity, intermittent or persistent, alternating unilaterally, bilaterally or bilaterally, with different manifestations. In allergic rhinitis, nasal congestion is often obvious due to the obvious edema of the nasal mucosa. In addition, due to the obvious edema of nasal mucosa, some patients still have hyposmia. Examination of the nasal mucosa is pale and edematous, and the nasal discharge is like clear water; it may also be combined with other type I allergic diseases such as bronchial asthma. Cytological examination of nasal secretions, skin test, excitation test and specific IgE antibody assay can help to identify. Currently, most of the cold medicine products on the domestic market are a combination of oral antihistamines and decongestants, which can relieve nasal congestion while controlling allergic symptoms. Clinically, we can see many patients complaining that they have had a cold for more than a month, and that they get better when they take cold medicine, but they get worse when they don’t. It is very easy to confuse the two. Since cold is a self-limiting disease, if the patient’s “cold” symptoms do not heal in 7-10 days, he should go to the hospital for specialist examination to exclude allergic rhinitis.