Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Efavirenz and carbamazepine may speed up how quickly your liver processes each other.
What might happen:
The amount of these medicines may decrease. Your efavirenz may not work as well against your HIV infection and your carbamazepine may not control your seizures.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know right away that you are taking these medicines together. Your doctor may want to check the amount of medicine in your blood or change your medicine.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.
1.Sustiva (efavirenz) US prescribing information. Bristol-Myers Squibb Company May 23, 2014.
2.Ji P, Damle B, Xie J, Unger SE, Grasela DM, Kaul S. Pharmacokinetic interaction between efavirenz and carbamazepine after multiple-dose administration in healthy subjects. J Clin Pharmacol 2008 Aug; 48(8):948-56.