Isoniazid tablets are available over the counter with a prescription order from a doctor, or in a hospital or CDC. Isoniazid tablets are antimicrobial drugs with bactericidal effect, which can inhibit the synthesis of mycolic acid of sensitive bacteria, thus causing the destruction of the pathogenic bacterial cell wall, and play an antibacterial activity. Clinically, it is commonly used in the treatment of tuberculosis, tuberculous meningitis and other tuberculous diseases. Common adverse reactions to isoniazid tablets include unsteady gait or numbness pinprick sensation, burning sensation or peripheral neuritis, dark urine, yellowing of the eyes or skin, loss of appetite, fatigue, nausea, and skin rash. It is contraindicated in patients with abnormal liver function, psychosis and epilepsy. It is recommended that patients consult a doctor before using the drug to avoid adverse effects, and if there is any discomfort in the process of using the drug, please consult a doctor for examination in time for treatment.