I have copd,,,just started having slight breathing problems, I also have inactive TB i got this over 35 yrs ago,but was never offered treatment until now,,,my doctor wants me to take medicine for it ISONIAZID 300 1 a day for 9 months ,,,does anyone know anything about this drug,, doc ,says hard on the liver,,,r there any other side effects? ??? Appreciate any replies. ..