Sequelae are very rare in patients with mild gas poisoning in clinical practice. The sequelae of gas poisoning are mostly closely related to moderate or severe gas poisoning. Patients with mild gas poisoning often experience dizziness, headache, ringing in the ears, blurred vision, nausea, vomiting, generalized weakness and other symptoms. Often mild gas poisoning patients, timely transfer to a well-ventilated place, away from the environment of gas poisoning, and give symptomatic, supportive treatment, most patients have no sequelae. For patients with moderate or severe poisoning, there are often sequelae. Patients with severe gas poisoning may have cerebral edema, pulmonary edema, cardiac arrhythmia, and some may even have delayed encephalopathy, limb paralysis and so on.