Occasionally, normal people bite their lips or tongues when eating, which is a normal physiological condition. If you bite your lips or tongue frequently, you need to rule out the presence of chronic fatigue. If you are too tired or work for a long period of time, this condition may also occur frequently. For example, peripheral facial palsy may also cause relaxation of one side of the facial muscles, retention of food in one side of the mouth, drooling and lip biting. In addition, it is more common for some elderly people with hypertension and diabetes to suddenly bite their lips during the process of eating, so attention should be paid to rule out the presence of a distorted mouth and eyes. This is because elderly people with hypertension and diabetes usually have risk factors for stroke. Many patients have strokes during eating, so look in the mirror to see if there is a slanted mouth and eyes, an asymmetrical nasolabial fold, or drooling. If there is a combination of weakness in one side of the arm and leg, the diagnosis becomes clearer and it is recommended to go to the neurology department of the local hospital to avoid delaying treatment.