Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
When these two medicines are taken together, your body may not process isoniazid properly.
What might happen:
This medication combination is often used together. However, there is a small risk that they could damage to your liver. Drinking alcohol while you are taking these medications may further increase the risk for liver damage.
What you should do about this interaction:
Let your healthcare professional (e.g. doctor or pharmacist) know that you are taking these two medications together. Your doctor may want to do tests to be sure your liver is working normally.Do not drink alcoholic beverages while you are taking these medicines.Contact your doctor if you experience persistent nausea, unusual fatigue, yellowing of the skin or eyes, or dark urine or pale stools.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Venho VM, Koskinen R. The effect of pyrazinamide, rifampicin and cycloserine on the blood levels and urinary excretion of isoniazid. Ann Clin Res 1971 Oct;3(5):277-80.
2.Llorens J, Serrano RJ, Sanchez R. Pharmacodynamic interference between rifampicin and isoniazid. Chemotherapy 1978;24(2):97-103.