Thumb numbness is considered to be caused by physiological factors such as cold and pressure, but also may be caused by peripheral neuritis, carpal tunnel syndrome and other diseases. 1. Physiological factors: If the weather is cold and you don’t do a good job of keeping warm, resulting in a cold thumb, or sleeping in an improper position to compress the nerves in the hand, it may lead to numbness of the thumb. 2. Peripheral neuritis: Peripheral neuritis is a disease of motor, sensory and autonomic disorders of the distal limbs, which can be caused by infection, endocrine disorders, nutritional disorders, etc. Patients will experience sensory, motor and autonomic dysfunction and other symptoms, which can be manifested as numbness of the thumb. 3. Carpal tunnel syndrome: Carpal tunnel syndrome is a disease caused by the compression of the median nerve in the carpal tunnel, the causes of which include exogenous compression, small lumen of the carpal tunnel, increased contents of the lumen, etc., which is mainly manifested as pain in the anterior part of the wrist, numbness and weakness of the hand, which will lead to numbness of the thumb of the patient. There are more causes of numbness of the thumb, and patients are advised to seek medical examination for a clear diagnosis.