Nirmatrelvir (Co Packaged With Ritonavir)
Pronunciation: (nir-MA-trel-veer in PAX-loh-vid).
- Generic name
- Nirmatrelvir (co-packaged with Ritonavir)
- Brand names
- Paxista, Paxlovid, Primovir, Nirmacom
- Drug class
- Antiviral (Protease Inhibitor)
Availability and supply rules vary by country
Trade names by country:
Australia: · Full directory
What Nirmatrelvir (co-packaged with Ritonavir) is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Nirmatrelvir (co-packaged with Ritonavir) works
Nirmatrelvir is a SARS-CoV-2 main protease (Mpro, also called 3CLpro) inhibitor. It blocks the activity of the viral protease enzyme required for processing polyproteins essential for viral replication. Ritonavir acts as a pharmacokinetic enhancer by inhibiting CYP3A-mediated metabolism, thereby increasing plasma concentrations of nirmatrelvir. (1) (2)
What Nirmatrelvir (co-packaged with Ritonavir) is used for
Treatment of mild-to-moderate COVID-19 in adults
Treatment of mild-to-moderate COVID-19 in adults
Treatment of mild-to-moderate COVID-19 in pediatric patients (12 years of age and older weighing at least 40 kg)
Treatment of mild-to-moderate COVID-19 in pediatric patients (12 years of age and older weighing at least 40 kg)
Reduction of risk of progression to severe COVID-19, including hospitalization or death
Reduction of risk of progression to severe COVID-19, including hospitalization or death
Before taking Nirmatrelvir (co-packaged with Ritonavir)
Do not take / not appropriate for
- Contraindicated in patients with severe renal (eGFR <30 mL/min) or hepatic impairment (Child-Pugh Class C), and in those taking drugs highly dependent on CYP3A for clearance. (Contraindication)
- Caution in patients with moderate renal impairment (dose adjustment required), liver disease, or those at risk for drug interactions. (Contraindication)
Tell your clinician about
How to take Nirmatrelvir (co-packaged with Ritonavir)
- General Instructions: Take Nirmatrelvir (in Paxlovid) exactly as prescribed by your healthcare provider. Start as soon as possible after diagnosis and within 5 days of symptom onset.. Adult Dosing: 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one tablet), taken together by mouth twice daily for 5 days.. Pediatric Dosing: For children 12 years and older and weighing at least 40 kg: same as adult dosing. Safety and efficacy have not been established in younger children.. Administration: Take with or without food. Swallow tablets whole; do not crush, chew, or split.. When To Stop: Complete the full 5-day course, even if you feel better. Do not stop early unless directed by your healthcare provider.. Storage: Store at room temperature (20°C to 25°C/68°F to 77°F), away from moisture and heat.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician.
Missed dose
If you miss a dose and it is within 8 hours of the scheduled time, take it as soon as you remember. If more than 8 hours have passed, skip the missed dose and take the next dose at the regular time. Do not double up doses.
Overdose
If you take too much Nirmatrelvir (in Paxlovid), seek emergency medical attention or call your local poison control center immediately. Supportive care is recommended as there is no specific antidote.
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Dysgeusia (altered taste)
Incidence: Reported in the clinician-authored database; frequency not established
Diarrhea
Incidence: Reported in the clinician-authored database; frequency not established
Nausea
Incidence: Reported in the clinician-authored database; frequency not established
Vomiting
Incidence: Reported in the clinician-authored database; frequency not established
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Increased liver enzymes
Incidence: Reported in the clinician-authored database; frequency not established
Rash
Incidence: Reported in the clinician-authored database; frequency not established
Signs of liver problems (yellowing of the skin/eyes, dark urine, severe stomach pain, unusual tiredness)
(1)Signs of a serious allergic reaction (rash, hives, swelling of the face/lips/tongue/throat, difficulty breathing)
(1)Serious warnings
Serious drug interactions are possible — serious
Symptoms: Serious drug interactions are possible; always review all medications with your provider. Not recommended for patients with severe kidney or liver impairment. May cause liver problems; monitor for signs of jaundice or dark urine. Use in pregnancy or breastfeeding only if clearly needed and after consulting your doctor. Not for use as pre- or post-exposure prophylaxis for COVID-19.
Action: Follow the urgency stated and seek prompt or emergency care when indicated.
UPDATED — the clinician database recorded severe renal impairment (eGFR <30 mL/min) as a contraindication — serious
Symptoms: UPDATED — the clinician database recorded severe renal impairment (eGFR <30 mL/min) as a contraindication; the current FDA label instead gives a specific reduced-dose regimen for severe renal impairment (see the renal dosing note below) rather than contraindicating use outright. Severe hepatic impairment (Child-Pugh Class C) remains not recommended because it has not been studied. Paxlovid is also contraindicated with drugs highly dependent on CYP3A for clearance where elevated concentrations are associated with serious/life-threatening reactions. Dose adjustment (not just caution) is required in moderate renal impairment.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (1) (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Nirmatrelvir (in Paxlovid) has significant drug-drug interactions, mainly due to ritonavir's inhibition of CYP3A4. It can increase levels of certain medications (e.g., antiarrhythmics, statins, immunosuppressants, sedatives), leading to serious or life-threatening reactions. Some drugs may reduce Paxlovid's effectiveness. Always provide your healthcare provider with a complete list of all medications, including over-the-counter drugs and supplements. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Paxlovid can be used in pregnancy; the FDA label states there are no available human data on nirmatrelvir use during pregnancy to evaluate drug-associated risk of major birth defects, miscarriage, or adverse maternal/fetal outcomes. COVID-19 in pregnancy carries its own risks of severe illness, so the decision to use Paxlovid during pregnancy should be made together with the treating obstetric/prescribing clinician, weighing the benefits of treating COVID-19 against the unknown drug-specific risk.
Breastfeeding
The FDA label reports that nirmatrelvir and ritonavir are present in human breast milk in small amounts (in a small lactation study, roughly 1.8% and 0.2% of the maternal weight-adjusted dose respectively). There are no data on effects on the breastfed infant or on milk production. Discuss breastfeeding during Paxlovid treatment with your doctor.
Children
Frequency: Not applicable.. Weight Based: Not recommended for pediatric use.. Max Daily Dose: Not applicable.. Max Single Dose: Not applicable.. Age Restrictions: Safety not established in children.
Renal_impairment
Current FDA labeling: mild renal impairment (eGFR 60 to <90 mL/min) needs no dose adjustment. Moderate renal impairment (eGFR 30 to <60 mL/min) requires a reduced dose (150 mg nirmatrelvir/100 mg ritonavir twice daily for 5 days). Severe renal impairment (eGFR <30 mL/min, including hemodialysis) uses a specific reduced regimen (see the renal dosing note below); on hemodialysis days, Paxlovid should be taken after dialysis. For hepatic impairment: no dose adjustment is needed in mild or moderate impairment (Child-Pugh Class A or B); Paxlovid is not recommended in severe hepatic impairment (Child-Pugh Class C) because it has not been studied there. This is more specific than, and updates, the clinician database's earlier 'contraindicated in severe renal impairment' framing.
Hepatic_impairment
Current FDA labeling: mild renal impairment (eGFR 60 to <90 mL/min) needs no dose adjustment. Moderate renal impairment (eGFR 30 to <60 mL/min) requires a reduced dose (150 mg nirmatrelvir/100 mg ritonavir twice daily for 5 days). Severe renal impairment (eGFR <30 mL/min, including hemodialysis) uses a specific reduced regimen (see the renal dosing note below); on hemodialysis days, Paxlovid should be taken after dialysis. For hepatic impairment: no dose adjustment is needed in mild or moderate impairment (Child-Pugh Class A or B); Paxlovid is not recommended in severe hepatic impairment (Child-Pugh Class C) because it has not been studied there. This is more specific than, and updates, the clinician database's earlier 'contraindicated in severe renal impairment' framing.
Monitoring
Storage
Store Paxlovid at room temperature (20°C to 25°C/68°F to 77°F), away from moisture and heat, in the original packaging.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Treatment of mild-to-moderate COVID-19 in adults
Dose summary: 300 mg of Nirmatrelvir (two 150 mg tablets) co-packaged with 100 mg of Ritonavir taken orally twice daily for 5 days.
Renal context: FDA label / Drugs.com dosage guide: mild renal impairment (eGFR >=60 to <90 mL/min) — no dosage adjustment. Moderate renal impairment (eGFR >=30 to <60 mL/min) — reduced dose: 150 mg nirmatrelvir with 100 mg ritonavir, twice daily for 5 days. Severe renal impairment (eGFR <30 mL/min, including hemodialysis) — 300 mg nirmatrelvir/100 mg ritonavir once on Day 1, then 150 mg nirmatrelvir/100 mg ritonavir once daily on Days 2-5; on hemodialysis days, dose after dialysis. This updates the clinician database's earlier framing of severe renal impairment as an outright contraindication. (1) (2)
Hepatic guidance
FDA label / Drugs.com dosage guide: no dosage adjustment is needed for mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment. Paxlovid is not recommended in patients with severe hepatic impairment (Child-Pugh Class C), because it has not been studied in that population.
Frequently asked questions
Who should take Nirmatrelvir (in Paxlovid)?
It is recommended for adults and children (12 years and older, weighing at least 40 kg) with mild-to-moderate COVID-19 who are at high risk for progression to severe disease.
How soon after COVID-19 symptoms should I start Paxlovid?
Start treatment as soon as possible after diagnosis and within 5 days of symptom onset for best effectiveness.
Can I take Paxlovid if I have kidney or liver problems?
Dose adjustments are needed for moderate kidney impairment. It is not recommended for severe kidney or liver impairment.
What should I do if I miss a dose?
Take the missed dose as soon as you remember if it is within 8 hours of the scheduled time. If more than 8 hours have passed, skip the missed dose and continue with your next dose.
Are there any foods or drinks I should avoid?
Avoid grapefruit and grapefruit juice, as they can increase the risk of side effects.
Can pregnant or breastfeeding women take Paxlovid?
Use during pregnancy or breastfeeding only if clearly needed and after consulting your healthcare provider.
Does Paxlovid cure COVID-19?
Paxlovid does not cure COVID-19 but reduces the risk of severe illness, hospitalization, and death when taken early in the course of infection.
What happens if I take too much Nirmatrelvir (in Paxlovid)?
Taking too much Nirmatrelvir (in Paxlovid) may lead to an increase in side effects such as diarrhea, nausea, and changes in taste. While severe overdose symptoms are not extensively documented, it is crucial to seek immediate emergency medical attention if an overdose is suspected or if you experience any unusual or severe symptoms.
Can I drink alcohol while taking Nirmatrelvir (in Paxlovid)?
It is generally advisable to limit or avoid alcohol consumption while taking Nirmatrelvir (in Paxlovid). Alcohol can potentially exacerbate certain side effects, such as gastrointestinal upset, and may also impact liver function, which is a consideration with protease inhibitors. Always consult your healthcare provider for personalized advice regarding alcohol and your medication.
Is Nirmatrelvir (in Paxlovid) safe during pregnancy?
Nirmatrelvir (in Paxlovid) is categorized as 'Consult doctor' for pregnancy. This means that the potential risks and benefits of using the medication during pregnancy need to be carefully evaluated by a healthcare professional. It is essential to inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding to discuss the safest treatment options for you.
What is the mechanism of action of Nirmatrelvir (co-packaged with Ritonavir)?
Nirmatrelvir is a SARS-CoV-2 main protease (Mpro, also called 3CLpro) inhibitor. It blocks the activity of the viral protease enzyme required for processing polyproteins essential for viral replication. Ritonavir acts as a pharmacokinetic enhancer by inhibiting CYP3A-mediated metabolism, thereby increasing plasma concentrations of nirmatrelvir. (1) (2)
What is the generic name of Nirmatrelvir (Co Packaged With Ritonavir)?
The generic name is Nirmatrelvir (co-packaged with Ritonavir). It is sold under brand names including Paxista, Paxlovid, Primovir, Nirmacom.
What class of drug is Nirmatrelvir (co-packaged with Ritonavir)?
Nirmatrelvir (Co Packaged With Ritonavir) is classed as: Antiviral (Protease Inhibitor).
References
- Clinician-authored medicine record for Nirmatrelvir (in Paxlovid) (MedGuideGlobal medicines database)MedGuideGlobal clinician-authored medicine record · null · accessed 2026-08-06 · source 1
- Paxlovid Dosage Guide — Drugs.comDrugs.com (reflecting current FDA-approved labeling) · United States · accessed 2026-08-07 · source 2
- PAXLOVID (NIRMATRELVIR AND RITONAVIR) KIT [PFIZER LABORATORIES DIV PFIZER INC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Nirmatrelvir and Ritonavir — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- Paxlovid — FDA approval record (Drugs@FDA NDA217188)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- Nirmatrelvir — RxNorm normalized drug concept (RXCUI 2587892)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient Nirmatrelvir (co-packaged with Ritonavir) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.