Since Paxlovid is cleared by the kidneys, dose adjustments may be required for patients with mild-to-moderate kidney disease, explains Dr. Topal. “For patients with severe kidney disease—or who are on dialysis—or those with severe liver disease, Paxlovid is not recommended; the levels of the drug can become too high and could cause increased side effects,” he says.

The FDA says that anyone who takes Paxlovid should contact their health provider right away if they have any signs and symptoms of liver problems: loss of appetite, yellowing of the skin and whites of the eyes (jaundice), dark-colored urine, pale-colored stools and itchy skin, or stomach-area (abdominal) pain.

It’s worth noting that because Paxlovid is still being monitored in the real world, it is possible that all of the risks are not yet known. (The FDA has provided a fact sheet on Paxlovid with a full list of known side effects.)

Do not take PAXLOVID if: You are allergic to nirmatrelvir, ritonavir, or any of the ingredients in PAXLOVID.

You are taking any of the following medicines:
​​​​​​​
o alfuzosin
o lomitapide
o ranolazine
o amiodarone
o lovastatin
o rifampin
o apalutamide
o lumacaftor/ivacaftor
o St. John’s Wort
o carbamazepine
o lurasidone (hypericum perforatum)
o colchicine o methylergonovine
o sildenafil (Revatio®) for o dihydroergotamine
o midazolam (oral) pulmonary arterial
o dronedarone
o naloxegol hypertension
o eletriptan
o phenobarbital
o silodosin
o eplerenone
o phenytoin
o simvastatin
o ergotamine
o pimozide
o tolvaptan
o finerenone
o primidone
o triazolam
o flecainide
o propafenone
o ubrogepant
o flibanserin
o quinidine
o voclosporin
o ivabradine

Taking PAXLOVID with these medicines may cause serious or life-threatening side effects or affect how PAXLOVID works.