<s>[INST] I have been taking Isoniazid 300mg 1x day (this is the first month of of a nine month treatment) and am concerned about the med s effect on my liver ( toxicity ). 1)Is there anything that can reduce the toxic side effect? 2) Would fiber psylium supplement be beneficial or not a good idea to help rid the body of waste (acetylisoniazid)? [/INST] The question is why are you taking Isoniazid ? Is it for prophylaxis or is it part of tuberculosis regimen ? Yes Isoniazid has liver toxicity but not in all patients . Only some patients develop raised liver enzymes because of isoniazid.  Do have an underlying liver disease ? If not there is nothing to worry. Go for a baseline Liver function test and repeat it after three months, if the ALT and AST has not increased by > 3 times the upper limit of normal then there is nothing to worry. You don't need to take any other medications to prevent liver toxicity. </s>