The Food and Drug Administration authorized Pfizer’s Paxlovid for mild to moderate Covid in people as young as 12 who have underlying conditions that raise the risk of hospitalization and death from the coronavirus, such as heart disease or diabetes. However, one of the two drugs in the antiviral cocktail could cause severe or life-threatening interactions with widely used medications, including statins, blood thinners and some antidepressants. And the FDA does not recommend Paxlovid for people with severe kidney or liver disease…

The Paxlovid cocktail consists of two tablets of the antiviral nirmatrelvir and one tablet of ritonavir, a drug that has long been used as what is known as a boosting agent in HIV regimens. Ritonavir suppresses a key liver enzyme called CYP3A, which metabolizes many medications, including nirmatrelvir. In the case of Paxlovid treatment, ritonavir slows the body’s breakdown of the active antiviral and helps it remain at a therapeutic level for longer.