Prescription medication · Antiviral (Protease Inhibitor Combination)

nirmatrelvir/ritonavir

Name: nirmatrelvir/ritonavir - FDA Drug Safety & Adverse Event Data
Creator: PlainMeds
License: https://creativecommons.org/publicdomain/zero/1.0/

Also sold as Paxlovid. Paxlovid treats mild to moderate COVID-19 in adults.

Compiled by PlainMeds Editorial, Drug Information Editorial Team

Data updated 2026-05-15

66,080
FDA reports: 86
InteractionsMany interactions: $69.72
Brand price (NADAC)

What the data shows

nirmatrelvir/ritonavir (Paxlovid) is a prescription Antiviral (Protease Inhibitor Combination), with 66,080 FDA adverse-event reports on file, with 86 documented drug interactions.

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

nirmatrelvir/ritonavir (Paxlovid) is a prescription Antiviral (Protease Inhibitor Combination). Paxlovid treats mild to moderate COVID-19 in adults.

Paxlovid is a medicine used to treat mild to moderate COVID-19 in adults. It helps prevent severe illness, hospitalization, or death in people at high risk.

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Drug Pricing (NADAC)

Brand Price

$69.72/unit

Generic Available

PFIZER

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

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What it does

Paxlovid treats mild to moderate COVID-19 in adults.

Common side effects

Change in taste, Diarrhea

Key warnings

Paxlovid can interact with many other medicines, causing serious or life-threatening problems.

The sections below are summarized in plain English from nirmatrelvir/ritonavir's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Paxlovid contains two medicines, nirmatrelvir and ritonavir. Nirmatrelvir stops the virus from multiplying in your body. Ritonavir helps nirmatrelvir stay in your body longer so it can work better.

How to Take It

Start taking Paxlovid as soon as possible after you test positive for COVID-19, and within 5 days of your symptoms starting. Take the tablets by mouth, with or without food. Take Paxlovid at about the same time each day. The usual dose is two 150 mg nirmatrelvir tablets and one 100 mg ritonavir tablet, all taken together twice a day for 5 days.

This is a plain-language summary of nirmatrelvir/ritonavir's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.

Pregnancy & Breastfeeding

There is not enough information about nirmatrelvir's safety during pregnancy. Studies on ritonavir in pregnant women have not shown an increased risk of birth defects. Talk to your doctor about the risks and benefits of taking Paxlovid if you are pregnant or breastfeeding.

This is a plain-language summary of nirmatrelvir/ritonavir's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.

Missed Dose

If you miss a dose of Paxlovid, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.

This is a plain-language summary of nirmatrelvir/ritonavir's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.

Storage

Store Paxlovid at room temperature, between 68°F to 77°F.

Side Effects (from patient reports)

Based on 66,080 FDA adverse event reports.

COVID-19

22,774
COVID-19 coming back

20,089
Change in taste

7,316
Diarrhea

4,003
Feeling sick to your stomach

2,620
Headache

2,156
Cough

2,041
Feeling tired

2,006
Wrong dose given

1,691
Throwing up

1,384

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Serious Warnings

Paxlovid can interact with many other medicines, causing serious or life-threatening problems. Before taking Paxlovid, tell your doctor about all the medicines you take. Your doctor may need to adjust the dose of your other medicines or monitor you more closely.

Known Drug Interactions

major simvastatin

HMG-CoA reductase inhibitors lovastatin, simvastatin ↑ lovastatin ↑ simvastatin Co-administration contraindicated due to potential for myopathy including rhabdomyolysis [see Contraindications (4) ] . If treatment with PAXLOVID is considered medically necessary, discontinue use of lovastatin and simvastatin at least 12 hours prior to initiation of PAXLOVID, during the 5 days of PAXLOVID treatment, and for 5 days after completing PAXLOVID.

Mechanism: This medicine stops your body from breaking down simvastatin, which can lead to high levels that cause serious muscle damage.

What to do: Stop taking simvastatin at least 12 hours before starting Paxlovid and do not start it again until 5 days after you finish the treatment.

major lovastatin

Mechanism: This medicine blocks the way your body processes lovastatin, which can cause the drug to reach dangerous levels and hurt your muscles.

What to do: You should stop taking lovastatin 12 hours before starting Paxlovid and wait 5 days after finishing Paxlovid before taking it again.

major sildenafil

Pulmonary hypertension agents (PDE5 inhibitors) sildenafil (Revatio ® ) ↑ sildenafil Co-administration of sildenafil with PAXLOVID is contraindicated for use in pulmonary hypertension due to the potential for sildenafil associated adverse events, including visual abnormalities hypotension, prolonged erection, and syncope [see Contraindications (4) ] . sildenafil, tadalafil, vardenafil ↑ sildenafil ↑ tadalafil ↑ vardenafil Dosage adjustment is recommended for use of sildenafil, tadalafil or vardenafil with PAXLOVID when used for erectile dysfunction.

Mechanism: This combination makes sildenafil stay in your body longer and at higher levels, which can cause your blood pressure to drop too low.

What to do: Avoid this combination if you take sildenafil for high blood pressure in the lungs, or talk to your doctor about a dose change if using it for erectile dysfunction.

major carbamazepine

Anticonvulsants carbamazepine , phenobarbital, primidone, phenytoin ↓ nirmatrelvir/ritonavir Co-administration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4) ] .

Mechanism: Carbamazepine makes your body get rid of the antiviral medicine too quickly, which prevents it from working against the virus.

What to do: Do not take these medicines together because the antiviral treatment will not be able to fight the infection properly.

major rifampin

Antimycobacterial rifampin, rifapentine ↓ nirmatrelvir/ritonavir Co-administration contraindicated due to potential loss of virologic response and possible resistance.

Mechanism: Rifampin causes the body to break down nirmatrelvir/ritonavir too quickly, which lowers the amount of medicine in your blood. This can make the treatment less effective and may lead to the virus becoming resistant.

What to do: Do not take these two medications together.

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This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.

Common Questions

How long do I take Paxlovid?

You will take Paxlovid for 5 days.

Can I take Paxlovid if I have kidney problems?

Your doctor may need to adjust your dose if you have kidney problems.

Can I take Paxlovid if I have liver problems?

Paxlovid is not recommended if you have severe liver problems.

What should I do if I feel sick while taking Paxlovid?

Contact your doctor if you feel sick or have any new symptoms while taking Paxlovid.

Can Paxlovid prevent me from spreading COVID-19 to others?

Completing the full 5-day treatment and isolating yourself helps to stop the spread of the virus.

What if my COVID-19 symptoms get worse after starting Paxlovid?

Tell your doctor immediately if your symptoms worsen or if you need to be hospitalized.

Can I take Paxlovid to prevent COVID-19?

No, Paxlovid is not approved to prevent COVID-19.

Will Paxlovid interact with my other medications?

Paxlovid can interact with many medications. Review all your medications with your doctor before starting Paxlovid.

What do the Paxlovid pills look like?

The nirmatrelvir tablets are pink and oval-shaped. The ritonavir tablets are white and capsule-shaped or ovaloid.

How should I dispose of unused Paxlovid?

Ask your pharmacist about the best way to dispose of unused Paxlovid. You can also check for local drug take-back programs.

What are the common side effects of nirmatrelvir/ritonavir?

The most commonly reported side effects of nirmatrelvir/ritonavir include Change in taste, Diarrhea. Based on 66,080 FDA adverse event reports. Always consult your healthcare provider about potential side effects.

Does nirmatrelvir/ritonavir interact with other medications?

Yes, nirmatrelvir/ritonavir has 86 known drug interactions. Notable interactions include simvastatin, lovastatin, sildenafil. Always inform your doctor about all medications you are taking.

What drug class is nirmatrelvir/ritonavir?

nirmatrelvir/ritonavir belongs to the Antiviral (Protease Inhibitor Combination) drug class. It requires a prescription (Rx). Paxlovid treats mild to moderate COVID-19 in adults.

Is nirmatrelvir/ritonavir safe during pregnancy?

There is not enough information about nirmatrelvir's safety during pregnancy. Studies on ritonavir in pregnant women have not shown an increased risk of birth defects. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

Related Medications in Antiviral (Protease Inhibitor Combination)

Other drugs grouped near nirmatrelvir/ritonavir - same-class peers and common alternatives.

acyclovir

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Acyclovir is an antiviral medicine.