- COVID-19 treatment in high-risk adults
- Prevention of COVID-19 hospitalization
- Prevention of COVID-19 death
- Treatment of mild-to-moderate COVID-19 in eligible patients
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Paxlovid
Generic Name: Nirmatrelvir/Ritonavir
Brand Names: Paxlovid
Paxlovid is an oral antiviral for mild-to-moderate COVID-19 in patients at high risk for severe disease.
AntiviralCOVID-19
Drug Class
Protease Inhibitor Combination (SARS-CoV-2 3CLpro Inhibitor + CYP3A4 Inhibitor/Pharmacokinetic Booster)
Pregnancy
Not formally categorized; insufficient human data — use during pregnancy only if potential benefit justifies potential risk
Available Forms
Co-packaged tablets: nirmatrelvir 150 mg (2 tablets) + ritonavir 100 mg (1 tablet) per dose
What It's Used For
Dosage Quick Reference
These are general dosage guidelines. Your doctor will determine the appropriate dose for your specific situation.
| Condition | Starting Dose | Typical Maintenance Dose |
|---|---|---|
| Mild-to-moderate COVID-19 (normal renal function, eGFR ≥60) | Nirmatrelvir 300 mg + Ritonavir 100 mg every 12 hours | Same dose for 5 days total |
| Mild-to-moderate COVID-19 (moderate renal impairment, eGFR 30–59) | Nirmatrelvir 150 mg + Ritonavir 100 mg every 12 hours | Same dose for 5 days total |
| Severe renal impairment (eGFR <30) | Not recommended | Not recommended |
Side Effects
Common Side Effects:
- Altered taste (dysgeusia) - metallic or bitter taste
- Diarrhea
- High blood pressure
- Muscle aches
- Nausea
- Abdominal pain
Serious Side Effects (seek immediate medical attention):
- Severe allergic reactions (rash, swelling, difficulty breathing)
- Liver problems (yellowing of skin/eyes, dark urine)
- Drug interactions causing serious adverse effects
- Worsening COVID-19 symptoms
Drug Interactions
Major Drug & Food Interactions
- Ritonavir is a potent CYP3A4 inhibitor — Paxlovid interacts with a very large number of medications. The following are particularly critical:
- Statins (lovastatin, simvastatin): Contraindicated — ritonavir dramatically increases statin levels, risking rhabdomyolysis. Atorvastatin dose should be reduced; rosuvastatin may be preferred.
- Immunosuppressants (tacrolimus, cyclosporine, sirolimus): Life-threateningly elevated levels possible; requires therapeutic drug monitoring and major dose adjustments or temporary hold.
- Direct oral anticoagulants (rivaroxaban, apixaban): Contraindicated with rivaroxaban; apixaban requires significant dose reduction or avoidance.
- Hormonal contraceptives (ethinyl estradiol): Ritonavir may reduce efficacy of combined oral contraceptives; use backup contraception.
- Benzodiazepines (midazolam, triazolam, alprazolam): Contraindicated or require major dose reduction due to excessive sedation risk.
- Colchicine: Significantly increased colchicine levels; reduce dose or avoid in patients with renal or hepatic impairment.
Additional Information
Paxlovid is an oral antiviral medication for treatment of mild-to-moderate COVID-19 in adults at high risk for progression to severe disease. It contains two medications: nirmatrelvir, which inhibits viral replication, and ritonavir, which boosts nirmatrelvir levels.
How Paxlovid Works
Nirmatrelvir is a SARS-CoV-2 main protease (Mpro) inhibitor. This protease is essential for viral replication, and blocking it prevents the virus from making functional proteins needed to reproduce. Ritonavir inhibits CYP3A4, slowing nirmatrelvir metabolism and keeping blood levels elevated for longer.
Composition and Dosing
Each dose consists of two nirmatrelvir 150 mg tablets plus one ritonavir 100 mg tablet, taken together twice daily for 5 days. Treatment should begin within 5 days of symptom onset. The medication comes in convenient daily dose packs.
Eligibility and Indications
Paxlovid is indicated for adults with positive COVID-19 test results who are at high risk for progression to severe disease. Risk factors include age 65+, obesity, diabetes, heart disease, lung disease, immunocompromising conditions, and others. It is not authorized for pre-exposure or post-exposure prevention.
Efficacy
Clinical trials showed Paxlovid reduced risk of hospitalization and death by approximately 89% when started within 5 days of symptoms in high-risk unvaccinated patients. Real-world data suggests continued effectiveness, though benefit may be less pronounced in vaccinated individuals.
Important Drug Interactions
Ritonavir is a potent CYP3A4 inhibitor, causing numerous significant drug interactions. Many medications are contraindicated including certain statins (lovastatin, simvastatin), sedatives (midazolam, triazolam), certain heart medications, and others. A thorough medication review is essential before prescribing.
Rebound Phenomenon
Some patients experience COVID-19 symptom rebound after completing Paxlovid treatment, with return of symptoms and positive tests. This typically occurs 2-8 days after initial recovery. The clinical significance and management of rebound is still being studied.
Special Populations
Dose adjustment is required for moderate renal impairment (eGFR 30-60 mL/min): nirmatrelvir is reduced to 150 mg with ritonavir 100 mg twice daily. Paxlovid is not recommended for severe renal or hepatic impairment. Safety during pregnancy has not been established.
Contraindications
Paxlovid is contraindicated in patients taking medications highly dependent on CYP3A for clearance where elevated levels could cause serious reactions. This includes certain medications for arrhythmias, seizures, and psychiatric conditions. Complete medication reconciliation is essential.
Access and Availability
Paxlovid is available by prescription at pharmacies. It transitioned from emergency use authorization to full FDA approval in May 2023 for adults and remains under EUA for pediatric patients 12 years and older weighing at least 40 kg.
Learn more at MedlinePlus
Frequently Asked Questions
Paxlovid should be started as soon as possible and within 5 days of symptom onset. The earlier treatment begins, the more effective it is at reducing the risk of severe illness and hospitalization. It is prescribed for adults who are at high risk for progressing to severe COVID-19.
Some patients experience a return of COVID-19 symptoms or test positive again a few days after completing the 5-day Paxlovid course. This "rebound" is generally mild and self-limited. It does not mean the medication failed — studies show Paxlovid still significantly reduces hospitalization risk even in patients who experience rebound.
The ritonavir component is known to cause dysgeusia (altered taste), often described as a metallic or bitter taste in the mouth. This side effect is temporary and resolves after completing the 5-day course. Sucking on hard candy or mints may help mask the taste.
Possibly. Because ritonavir is a strong CYP3A4 inhibitor, it interacts with many medications. Your doctor or pharmacist must review all your medications before prescribing Paxlovid. Some drugs may need to be temporarily paused, dose-adjusted, or substituted during the 5-day treatment course.
Yes. Paxlovid is prescribed based on risk factors for severe disease (age 50+, obesity, diabetes, cardiovascular disease, immunocompromised status, etc.), regardless of vaccination status. Vaccination reduces your risk of severe COVID-19, and Paxlovid provides an additional layer of protection.
Questions to Ask Your Doctor
Consider discussing these topics at your next appointment:
- ✓Am I at high enough risk for severe COVID-19 to benefit from Paxlovid?
- ✓Which of my current medications need to be paused or adjusted during the 5-day course?
- ✓Should I be concerned about Paxlovid rebound, and what should I do if symptoms return?
Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.
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Questions About This Medication?
Talk to your doctor or pharmacist about whether Paxlovid is right for you.
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