nirmatrelvir/ritonavir Paxlovid is the top at-home treatment for moderate to severe cases of Covid-19, shown to reduce risk of hospitalization or death by 89% if taken within the first 5 days of symptoms. It comes in the form of oral antiviral tablets, taken twice a day over the course of 5 days. Read more about Covid-19.
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How to use this information
This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of a healthcare professional. If you have questions, go to your patient dashboard and request a medical provider callback for complete information about this product and your specific health needs.
Medication name
  • COMMON BRAND NAME(S): Paxlovid
What you should know about Paxlovid: 
  • The combination of Nirmatrelvir tablets and Ritonavir tablets is a product that the FDA is allowing to be given for emergency use to treat Covid-19. The product is also approved to be used in Canada to treat Covid-19. It is used by people who have recently tested positive for coronavirus, have had mild to moderate symptoms for no more than 5 days and are not hospitalized. 
  • To receive this product you must also be at high risk for Covid-19 complications due to older age, obesity, or ongoing medical conditions (such as lung or heart disease or diabetes, among others). Request a medical provider callback in your patient dashboard if you have questions about the risks and benefits of treatment with Nirmatrelvir and Ritonavir.
  • Nirmatrelvir is a SARS-CoV-2 main protease inhibitor. It works by preventing the growth of the virus that causes Covid-19. Ritonavir increases ("boosts") the levels of Nirmatrelvir. This helps Nirmatrelvir work better. More information about Nirmatrelvir and Ritonavir is available from the FDA Fact Sheet for Patients, Parents, and Caregivers for Emergency Use.
  • Study results show that Nirmatrelvir and Ritonavir may help people who are at high risk for developing complications of Covid-19 stay out of the hospital.
  • The information in this document reflects emerging data, which is evolving and subject to reassessment. Patients should be aware of these considerations in their review of Nirmatrelvir and Ritonavir.
How to take Paxlovid: 
  • Take this medication by mouth with or without food, usually once in the morning and once in the evening for 5 days. Swallow the tablets whole. Do not chew, break, or crush the tablets. The dosage is based on your medical condition and response to treatment.
  • Continue to take this medication for the full time prescribed.
  • Stopping the medication too early may allow the virus to continue to grow, which may result in a return of the infection or failure to protect you from the virus.
  • If you develop severe difficulty breathing, chest pain, lightheadedness or dizziness with minimal exertion, you should seek immediate in person care.
Potential side effects: 
  • Changes in taste, diarrhea, high blood pressure, or muscle pain may occur. If any of these effects last or get worse, request a medical provider callback or contact your primary care provider promptly.
  • Contact us right away if you have any serious side effects, including: signs of liver problems (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine).
  • A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
  • Information is limited and it is unknown at this time if Nirmatrelvir and Ritonavir cause other serious side effects. This is not necessarily a complete list of possible side effects.
What to know about Paxlovid rebound
  • According to the CDC, a small percentage of patients may experience “Paxlovid rebound” where Covid-19 symptoms briefly return 2-8 days after initial recovery. Researchers are still trying to understand why this is and whether it’s tied to Paxlovid or other factors. However the medication continues to be recommended as the most effective treatment for early-stage treatment of mild to moderate Covid-19 among high risk patients. 
  • For those that do experience rebound Covid-19, the symptoms are usually milder and there are no reports of progression to severe disease or a need for additional treatment. Patients may still be contagious and should continue isolating to avoid passing the virus to others. 
  • We will continue to update this information as new data and guidance becomes available.
Precautions to be aware of
  • Before taking this medication, contact us if you have any allergies. This product may contain inactive ingredients which can cause allergic reactions or other problems.
  • Limited information is known at this time about other medical conditions that may affect how Nirmatrelvir and Ritonavir work, or how Nirmatrelvir and Ritonavir may affect other medical conditions.
  • Before using this medication, contact us if you have a medical history of: kidney disease, liver disease, HIV infection.
  • To avoid spreading the virus, you should continue to take precautions such as self-isolation, wearing a mask, social distancing (physical distancing), washing hands, and not sharing personal items.
  • Request a callback from a medical provider if you are pregnant or think you are pregnant.
  • It is unknown if Nirmatrelvir passes into breast milk. Ritonavir does pass into breast milk. The risks of breast-feeding while infected with Covid-19 and while using this product should be discussed with a medical provider.
Drug interactions

Drug interactions may change how your medications work or increase your risk for serious side effects.This document does not contain all possible drug interactions.

Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with the medical provider or pharmacist if in doubt. Do not start, stop, or change the dosage of any medicines without speaking with a medical provider.

Ritonavir can slow down or speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include:

  • Alfuzosin, antiarrhythmics (such as amiodarone, flecainide, propafenone, quinidine)
  • Azole antifungals (such as voriconazole)
  • Certain benzodiazepines (midazolam, triazolam)
  • Certain "blood thinners" (such as rivaroxaban, warfarin)
  • Eletriptan
  • Drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as avanafil, sildenafil)
  • Ergot alkaloids (such as dihydroergotamine, DHE, Ergonovine, ergotamine, methylergonovine)
  • Lurasidone
  • Opioid pain medications (such as fentanyl, meperidine)
  • Pimozide
  • Ranolazine
  • Salmeterol
  • "Statin" cholesterol drugs (such as simvastatin, lovastatin), among others.

Other medications can affect the removal of Ritonavir from your body, which may affect how Ritonavir works. Examples include:

  • Apalutamide
  • Rifampin
  • St. John's wort
  • Drugs used to treat seizures (such as carbamazepine, phenobarbital, phenytoin), among others.

This medication may decrease the effectiveness of hormonal birth control (containing ethinyl estradiol) such as pills, patch, or ring. This could cause pregnancy. Request a callback from a medical provider to discuss using reliable backup birth control methods while using this medication. Also, contact us if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

What to do in the event of an overdose

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222.

Additional notes

Do not share this medication with others. Lab and/or medical tests (such as pregnancy tests or kidney and liver lab tests) may be done while you are taking this medication. Keep all medical and lab appointments.

What to do if you miss a dose
  • If you miss a dose, take it as soon as you remember if it is less than 8 hours after the time you would usually take it.
  • If more than 8 hours have passed, skip the missed dose. Take your next dose at the regular time.
  • Do not double the dose to catch up.
How to store this medication
  • Store at room temperature away from light and moisture.
  • Do not store in the bathroom. Keep all medications away from children and pets.
  • Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Treatment for
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