Isoniazid is used to treat tuberculosis (TB). TB is a bacterial infection which mostly affects the lungs, but which can affect any part of your body. It is treatable with a course of medicines which usually lasts for six months in total. You will need to take several medicines to treat TB - isoniazid is just one of the medicines prescribed.
This is a companion discussion topic for the original article at https://patient.info/medicine/isoniazid-for-tuberculosis