You can breathe through your mouth, but you can’t breathe through your mouth for a long time, so you need to find out the cause of nose breathing and treat it. 1. Common cold: common cold will have symptoms of nasal congestion, sneezing, runny nose and other symptoms, you can use topical pseudoephedrine hydrochloride to relieve nasal congestion, taking antihistamines such as loratadine to relieve the symptoms of sneezing and runny nose. 2. Allergic rhinitis: it is necessary to stay away from allergens as far as possible, keep the air fresh, and use glucocorticosteroids (such as budesonide) and antihistamines (such as cetirizine) reasonably. 3. Nasal polyps: in addition to poor breathing, nasal polyps can also be manifested as increased nasal secretions, olfactory disorders and so on. Topical or oral glucocorticosteroids (e.g. fluticasone propionate nasal spray) or oral leukotriene receptor antagonists (e.g. montelukast sodium) can be used, and surgery can be taken if necessary. 4. Deviated septum: For patients with deviated septum that seriously affects normal life, surgical treatment is the mainstay. When the nose is not breathing well, it is recommended to actively seek medical treatment to find the cause of the disease for targeted medication and treatment.