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KNOXVILLE, Tenn. (WATE) – On Wednesday, the U.S. Food and Drug Administration issued an emergency use authorization for Pfizer’s COVID-19 pill for home use. It is the first pill authorized against COVID-19 in the U.S.

Here are six things to know about the Pfizer antiviral pill and the next steps health regulators could take as the country faces what officials are calling another troubling surge in COVID-19 cases.

Anti-COVID pill name: Paxlovid

Pfizer’s anti-COVID pill is called Paxlovid, and is available by prescription only, according to the FDA. Paxlovid is given as three tablets, two nirmatrelvir tablets and one ritonavir tablet, co-packaged for oral use.

Who can take Paxlovid

The FDA says Paxlovid is for the treatment of mild-to-moderate coronavirus disease (COVID-19) in adults and pediatric patients (12 years of age and older weighing at least 88 pounds) with positive results of direct SARS-CoV-2 testing, and who are at high risk for progression to severe COVID-19, including hospitalization or death.

When to take Paxlovid

Paxlovid should be taken as soon as possible, the FDA says, after a diagnosis of COVID-19 and within five days of symptom onset.

Symptoms appear differently for different people, but the most commonly reported symptoms include:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea
  • Trouble breathing
  • Persistent pain or pressure in the chest
  • New confusion
  • Inability to wake or stay awake
  • Pale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone

What Paxlovid does

The FDA says Paxlovid consists of nirmatrelvir, which inhibits a SARS-CoV-2 protein to stop the virus from replicating, and ritonavir, which slows down nirmatrelvir’s breakdown to help it remain in the body for a longer period at higher concentrations.

Paxlovid is given as three tablets (two tablets of nirmatrelvir and one tablet of ritonavir) taken together orally twice daily for five days, for a total of 30 tablets. Paxlovid is not authorized for use for longer than five consecutive days. 

What Paxlovid is not

Health regulators also clarified Wednesday that Paxlovid is not authorized for pre-exposure or even post-exposure prevention to COVID-19, nor is it a substitute for treatment in those requiring hospitalization due to severe or critical COVID-19 infection.

Paxlovid is also not a substitute for vaccination.

Paxlovid is not recommended in patients with severe kidney or severe liver impairment.

Possible side effects

The FDA says possible side effects of Paxlovid include impaired sense of taste, diarrhea, high blood pressure and muscle aches. Using Paxlovid at the same time as certain other drugs may result in potentially significant drug interactions. Using Paxlovid in people with uncontrolled or undiagnosed HIV-1 infection may lead to HIV-1 drug resistance. Ritonavir may cause liver damage, so caution should be exercised when giving Paxlovid to patients with preexisting liver diseases, liver enzyme abnormalities or liver inflammation.  

More information about Paxlovid and the FDA’s full statement on the Pfizer anti-COVID pill is available on its website.