Hepatitis B can cause symptoms of fatigue and dry heaving, but the sudden appearance of fatigue and dry heaving in patients with hepatitis B may also be caused by the combination of other diseases, such as electrolyte disorders, vestibular dysfunction and so on. 1. Hepatitis B: Hepatitis B can lead to symptoms of fatigue and dry heaving, which is caused by loss of appetite and disturbance of sugar metabolism by liver, and patients can have other symptoms such as abdominal distension, jaundice and pain in liver area. 2. Electrolyte disorders: if patients with hepatitis B have ascites and take diuretics such as hydrochlorothiazide, electrolyte disorders may occur, which may lead to symptoms of fatigue, dry heaving, and patients may also have symptoms such as dizziness and panic. 3. Vestibular dysfunction: Hepatitis B patients who also suffer from vestibular neuronitis and other diseases can also lead to sudden weakness, dry heaving symptoms, in addition, the patient will also have dizziness, nystagmus and other symptoms. In addition to the above factors, other reasons can also lead to the symptoms of sudden weakness, dry heaving symptoms of the patient, it is recommended to consult a doctor in time to identify the causes and ask the doctor to deal with it.