• Home
  • Latest
  • Fortune 500
  • Finance
  • Tech
  • Leadership
  • Lifestyle
  • Rankings
  • Multimedia
Health

What to know about Paxlovid: Side effects, drug interactions, and rebound infections

By
Alexa Mikhail
Alexa Mikhail
Senior Reporter, Fortune Well
Down Arrow Button Icon
By
Alexa Mikhail
Alexa Mikhail
Senior Reporter, Fortune Well
Down Arrow Button Icon
June 17, 2022, 3:35 PM ET
paxlovid medicine
Fabian Sommer—picture alliance/Getty Images

In December, the Food and Drug Administration authorized emergency use of Pfizer’s antiviral pill Paxlovid for people at high risk of developing severe COVID-19. The drug was 89% effective in reducing the risk of hospitalization and death when taken within three days of the onset of symptoms, and 88% effective for reducing hospitalization and death when taken within five days, according to a study performed by Pfizer. 

“This is kind of helping us transition from an epidemic phase into an endemic phase for COVID,” says Dr. Andrew Jameson, section chief of infectious diseases at Trinity Health Saint Mary’s Hospital. “These oral antivirals are really important tools to help us get to the point where we can live with COVID without it hurting as many people. That’s the whole goal right now.” 

This week, Pfizer halted a trial looking into the drug’s efficacy for those with a “standard risk” for developing severe COVID, citing a “non-significant” reduction in hospitalization and death for this group. Still, medical professionals tout Paxlovid’s impact for those in high-risk groups.

How does Paxlovid work?

Paxlovid is an antiviral therapy and a combination of two drugs (nirmatrelvir and ritonavir) that help prevent replication of the virus’s protein particles responsible for the spread of COVID in the body. 

Who should take Paxlovid?

Paxlovid is for people age 12 and older, with mild to moderate cases of COVID-19, who are at high risk for developing severe COVID. High-risk groups include those with certain underlying conditions, like diabetes, people who’ve had an organ transplant or who are over 65. The list of high-risk conditions is long and nuanced, so it’s best to talk to your doctor to determine whether you’re in this group.

When should I take Paxlovid? 

For Paxlovid to be effective, it needs to be taken within five days of developing symptoms. 

How do I get Paxlovid? 

“The message that I really would like to get out is, have a plan,” said Dr. Preeti Malani, professor of medicine in the division of infectious diseases at the University of Michigan. 

Malani says to contact a primary care doctor to prescribe the medication as soon as you test positive. An at-home rapid test is sufficient to get the prescription, so you don’t have to scramble to find further testing while contagious. Additionally, you can go to urgent care (some pharmacies have urgent care), where you can make an appointment online, take a test, meet with a provider, and get a prescription for the antiviral pill. 

What are the side effects of Paxlovid? 

The most common side effects include nausea, upset stomach, diarrhea, impaired taste, and muscle aches. 

Tell your doctor or health care professional about conditions you have or other drugs you’re taking. Those with severe kidney or liver disease should not take the medication, says Dr. Scott Roberts, associate medical director of infection prevention at Yale New Haven Hospital. Some medications, like those used for heart arrhythmias and to lower cholesterol, for example, can have an unsafe interaction.

“That doesn’t mean you can’t take it. It might mean it’ll be recommended that you hold a medication like a cholesterol pill, for example, but it’s really important that whoever’s prescribing medications to you knows what drugs you’re taking,” Malani says.

What is Paxlovid rebound? 

Recently, there have been reports about a “rebound effect” for those taking Paxlovid, a phenomenon where people’s symptoms improve, only to return two to eight days after their initial recovery.

Jameson suspects that because patients take the oral medication early in the disease’s progression, their immune system has not gone through its entire process of mitigating the virus. 

“Your immune system hasn’t really had a chance to catch up and really create enough antibodies to have a sustained response,” Jameson says. 

A study released this week from the Mayo Clinic found that out of the 483 qualified patients treated with Paxlvoid, only four reported rebound symptoms. 

“There’s no data to suggest that these people need extra treatment courses…but it’s a new finding, so there’s a lot of investigation going into this right now,” Roberts says.

Medical experts say further research is needed to understand the nuances in these cases but note that hospitalization remains reduced, and those at high risk for developing severe COVID-19 cases should still consider taking the drug. 

“At the start of this pandemic, I never would have imagined something so successful as a therapeutic that is oral that can be taken at home,” says Roberts. “I think this is really remarkable.”

Sign up for the Fortune Features email list so you don’t miss our biggest features, exclusive interviews, and investigations.

About the Author
By Alexa MikhailSenior Reporter, Fortune Well
LinkedIn iconTwitter icon

Alexa Mikhail is a former senior health and wellness reporter for Fortune Well, covering longevity, aging, caregiving, workplace wellness, and mental health.

See full bioRight Arrow Button Icon

Latest in Health

Best protein lead image
HealthDietary Supplements
The 8 Best Protein Powders of 2025: How to Choose, According to an RD
By Christina SnyderDecember 9, 2025
1 day ago
Transparent Labs Creatine HMB as best creatine
HealthDietary Supplements
The Best Creatine Supplements of 2025: Tested and Approved
By Christina SnyderDecember 9, 2025
1 day ago
Jon Rosemberg
CommentaryProductivity
The cult of productivity is killing us
By Jon RosembergDecember 9, 2025
2 days ago
Trump
CommentaryTariffs and trade
AI doctors will be good at science but bad at business, and big talk with little action means even higher drugs prices: 10 healthcare predictions for 2026 from top investors
By Bob Kocher, Bryan Roberts and Siobhan Nolan ManginiDecember 9, 2025
2 days ago
Kevin Kiley
PoliticsElections
‘It absolutely matters politically’: Swing-district Republicans alarmed at spiking health insurance premiums tipping midterms
By Marc Levy, Kevin Freking and The Associated PressDecember 8, 2025
2 days ago
HealthHealth
These toxic wild mushrooms have caused a deadly outbreak of poisoning in California
By The Associated PressDecember 7, 2025
3 days ago

Most Popular

placeholder alt text
Politics
Exclusive: U.S. businesses are getting throttled by the drop in tourism from Canada: ‘I can count the number of Canadian visitors on one hand’
By Dave SmithDecember 10, 2025
15 hours ago
placeholder alt text
Success
At 18, doctors gave him three hours to live. He played video games from his hospital bed—and now, he’s built a $10 million-a-year video game studio
By Preston ForeDecember 10, 2025
17 hours ago
placeholder alt text
Economy
‘Fodder for a recession’: Top economist Mark Zandi warns about so many Americans ‘already living on the financial edge’ in a K-shaped economy 
By Eva RoytburgDecember 9, 2025
1 day ago
placeholder alt text
Economy
‘Be careful what you wish for’: Top economist warns any additional interest rate cuts after today would signal the economy is slipping into danger
By Eva RoytburgDecember 10, 2025
9 hours ago
placeholder alt text
Uncategorized
Transforming customer support through intelligent AI operations
By Lauren ChomiukNovember 26, 2025
14 days ago
placeholder alt text
Economy
The 'forever layoffs' era hits a recession trigger as corporates sack 1.1 million workers through November
By Nick Lichtenberg and Eva RoytburgDecember 9, 2025
1 day ago
Rankings
  • 100 Best Companies
  • Fortune 500
  • Global 500
  • Fortune 500 Europe
  • Most Powerful Women
  • Future 50
  • World’s Most Admired Companies
  • See All Rankings
Sections
  • Finance
  • Leadership
  • Success
  • Tech
  • Asia
  • Europe
  • Environment
  • Fortune Crypto
  • Health
  • Retail
  • Lifestyle
  • Politics
  • Newsletters
  • Magazine
  • Features
  • Commentary
  • Mpw
  • CEO Initiative
  • Conferences
  • Personal Finance
  • Education
Customer Support
  • Frequently Asked Questions
  • Customer Service Portal
  • Privacy Policy
  • Terms Of Use
  • Single Issues For Purchase
  • International Print
Commercial Services
  • Advertising
  • Fortune Brand Studio
  • Fortune Analytics
  • Fortune Conferences
  • Business Development
About Us
  • About Us
  • Editorial Calendar
  • Press Center
  • Work At Fortune
  • Diversity And Inclusion
  • Terms And Conditions
  • Site Map

© 2025 Fortune Media IP Limited. All Rights Reserved. Use of this site constitutes acceptance of our Terms of Use and Privacy Policy | CA Notice at Collection and Privacy Notice | Do Not Sell/Share My Personal Information
FORTUNE is a trademark of Fortune Media IP Limited, registered in the U.S. and other countries. FORTUNE may receive compensation for some links to products and services on this website. Offers may be subject to change without notice.