Drug Interactions between atazanavir / cobicistat and ritonavir

Using atazanavir together with ritonavir may increase the effects of atazanavir. Contact your doctor if you experience increased urination or extreme thirst, severe pain in your side or lower back, painful urination, blood in your urine, easy bruising or bleeding, signs of a new infection, such as fever or chills, cough, or flu symptoms, or jaundice (yellowing of the skin or eyes). If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Cobicistat is a medication used to boost the effects of some medications that treat HIV infection. However, using cobicistat together with other HIV medications, such as ritonavir, may alter the blood levels and effects of both medications. Using ritonavir with cobicistat may reduce or increase blood levels of cobicistat. Reduced blood levels of cobicistat may make cobicistat less effective and may cause overall HIV treatment to be less effective. Cobicistat may increase blood levels of ritonavir which may increase the risk of side effects. Talk to your doctor or pharmacist if you have any questions on how to use these medications properly. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. Contact your doctor if your condition changes or you experience increased side effects. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.