Monadox Doxycycline Rifampicin + Isoniazid
ModerateRifampicin + Isoniazid and doxycycline are listed together as medicines that interact. The text does not say what the effect is or what to do about it.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.