Recently, we have received a lot of patients or online consultation or telephone consultation who had a history of carbon monoxide poisoning, and after the symptoms of headache, panic, nausea and vomiting were more obvious at the time with or without coma, they all went through hospital treatment in the acute stage, and most of them did hyperbaric oxygen therapy. In a few days or months after the headache, panic, insomnia, abdominal pain, memory loss and other symptoms, and even some people feel unstable walking, or walking to the side to lean. At this time, they often suspect that they have carbon monoxide poisoning late onset encephalopathy, fearful of the end of the day, around to see a doctor, affecting normal life, some took a brain MRI, some lesions on the report, more convinced that the late onset encephalopathy. In some cases, the MRI report shows some lesions, so they believe it is late-onset encephalopathy. Whether it is late-onset encephalopathy sometimes requires clinical observation. Generally speaking, late-onset encephalopathy is likely to occur 2-4 weeks after acute carbon monoxide poisoning, with dementia, hypertonia, unsteadiness in walking, incontinence as common manifestations, and of course various other atypical manifestations. Generally, the chance of late onset encephalopathy occurring more than 4 weeks later is very small. I have seen few cases of late onset encephalopathy, but I have experienced several patients who had been diagnosed with late onset encephalopathy and were finally denied after clinical observation, which is reported in the literature. The Chinese Medical Journal of Emergency Medicine defines the time of onset of delayed onset encephalopathy as 2-8 weeks after carbon monoxide poisoning. Of course, there are individual patients diagnosed with cerebral infarction and vascular dementia who were diagnosed with carbon monoxide poisoning late onset encephalopathy after clinical observation and treatment were cured by treatment. The incidence of late onset encephalopathy in carbon monoxide poisoning has increased in the last decade, and the analysis is related to the increase in the incidence of underlying diseases (hypertension, diabetes, coronary heart disease, hyperlipidemia) in the population, and also to the increase in the level of resuscitation, as some patients may not have been saved in the past, but now the success rate of resuscitation has increased. Clinicians in neurology, emergency medicine, and internal medicine have a clear understanding of late-onset encephalopathy and will explain the possibility of late-onset encephalopathy to patients or their families so that they can pay attention to it. It is important to pay attention to and prevent late-onset encephalopathy, but do not let it affect your life for many years afterwards. Some patients think about late-onset encephalopathy for many years after carbon monoxide poisoning, and the slightest movement of wind will make them think about late-onset encephalopathy, affecting their mood, sleep and quality of life. This is the time to see an experienced doctor for diagnosis and identification, not self-diagnosis. Online consultation is also available for guidance. At this time, you should describe the condition in detail and upload relevant imaging studies.