How the interaction occurs:
Rifampin may speed up how quickly your body processes efavirenz.
What might happen:
The amount of efavirenz in your blood may decrease and it may not work as well.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together or if you have taken rifampin in the previous two weeks. Your doctor may want to change the amount of efavirenz you are taking, especially if you weigh 50 kg (110 lbs) or more. Your doctor also may want to check how your efavirenz is working.Your healthcare professionals 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.Reference:1.Sustiva (efavirenz) US prescribing information. Bristol-Myers Squibb Company March, 2015.