Left deviation of the nasal septum may have no effect in mild cases, but in serious cases, nasal congestion, nosebleed, headache and even sinusitis may occur. 1. Nasal congestion: When the left deviation of the nasal septum is more serious, the left side of the nasal cavity is narrower, which often causes nasal congestion on the left side. The right inferior turbinate may be compensatory hypertrophy over time, which may cause right-sided nasal congestion, and eventually lead to bilateral nasal congestion. 2. Nosebleed: when the deviated nasal septum is protruding into the left nasal cavity in the way of bone spine or bone ridge, the mucous membrane there is often thin and tense, which stimulates the mucous membrane when the airflow comes in and out, thus easily causing nosebleed. 3. Headache: When the deviated bone presses the submucosal nerve of the inferior turbinate or middle turbinate, it can cause recurrent rhinogenic headache. 4. Sinusitis: When the deviated nasal septum affects the drainage of the sinuses, the secretions in the sinuses are not excreted properly, which in turn causes inflammation and leads to the occurrence of sinusitis. If you have a deviated nasal septum, it is recommended that you consult a hospital as soon as possible and follow the doctor’s instructions according to the specific situation.