An overdose of isoniazid, depending on body weight, can affect liver function impairment, most commonly an increase in the liver’s transaminases or a decrease in the ability to metabolize the drug. Because of individual differences in body composition, different patients will experience different liver damage at the same dose. When the dose is too high, close monitoring, according to the needs of the disease, the doctor and the patient timely communication, and need to monitor the liver function, plus vitamin B6 to avoid the occurrence of peripheral neuritis. Specific medication should be combined with clinical, by the doctor’s face-to-face guidance shall prevail.