No. Isoniazid-rifampin has not been formally assigned to a pregnancy categoy by the fda. Isoniazid-rifampin is only recommended for use during pregnancy when benefit outweighs risk. Both of them have been assigned to a pregnancy category c by the fda. There are no controlled data in human pregnancy; however, both of them known to cross the placental barrier and appear in a cord blood. No bf recommen.
No. Both drugs are category c, which means there are no direct human harm shown, but animal studies show adverse effects on the fetus. The benefits may outweigh the risks, under certain circumstances, this should be discussed with your doctor. Rifampin is considered safe with breast feeding while Isoniazid is not and may decrease flow and quality of milk.
Depends. Isoniazid is a category c medication (not enough data to show baby harming risks in humans and/or limited studies to show baby harming risks in animals) and considered "possibly unsafe" in lactation/breastfeeding. The decision to use any medication must be informed and made after a careful evaluation of the risks and benefits. Only you and your doctor can answer this question.
Yes. If in doubt, call your local pharmacist.