What reactions can overuse (very long duration) use of inh (isoniazid) cause in the body? does it do the opposite like cause fungal overgrowth?

INH: An infectious disease specialist who works a lot with INH for tb patients is best qualified to answer your question, but I'm not aware that long term use causes fungal overgrowth. Liver function is monitored when it is prescribed however.

INH is fairly safe d: It is a relatively safe drug. Its one toxicity of concern is a mild hepatitis which, fortunately is relatively uncommon. There is no risk of fungal infections. You should not take it for any more than one year maximum. If you have taken it for one year, you should be able to stop it after speaking with your treating physician.