Isoniazid can be taken after meals, taking the drug after meals can reduce the irritation of the drug on the gastrointestinal tract. Isoniazid is an anti-tuberculosis drug that may irritate the mucous membranes of the gastrointestinal tract and cause nausea, vomiting, and stomach discomfort when taken on an empty stomach. Taking it after meals can reduce the irritation of the drug to the gastrointestinal tract and minimize nausea, vomiting and other gastrointestinal adverse reactions. Therefore, isoniazid can be taken after meals. Isoniazid is contraindicated in patients with allergy, acute liver disease, psychosis, etc. Isoniazid may cause peripheral neuropathy, hepatitis, jaundice, nausea, vomiting, fatigue, rash, impotence and other adverse reactions in some patients. The above drugs should be taken in strict compliance with the doctor’s instructions, and if any uncomfortable symptoms occur after taking the drugs, they should go to the hospital in time for timely treatment.