Nirmatrelvir; Ritonavir

What it is

Nirmatrelvir; ritonavir is a five-day course of tablets taken together for COVID-19. Nirmatrelvir is the active antiviral: it blocks the SARS-CoV-2 main protease, the enzyme the virus needs to cut its own proteins into working pieces. Ritonavir is not active against SARS-CoV-2 at all; it is included because it blocks the liver enzyme CYP3A that would otherwise destroy nirmatrelvir too quickly. That booster role is also the source of the drug's biggest practical problem, because CYP3A clears a very long list of other medicines.

What the research says

In the trial that led to approval, EPIC-HR, unvaccinated adults at high risk who started the drug within three days of symptoms had a 0.77% rate of COVID-19 hospitalisation or death by day 28 versus 7.01% on placebo - an absolute difference of 6.32 percentage points. That population no longer resembles most people today. In EPIC-SR, which enrolled vaccinated people with a risk factor and unvaccinated people at standard risk, the drug did not shorten symptoms at all (12 days versus 13, P = 0.60) and the difference in hospitalisation or death was not statistically significant. A meta-analysis of 47 Omicron-era cohort studies in 10.8 million patients still finds fewer hospitalisations and deaths, but puts the number needed to treat to prevent one COVID-19 hospitalisation at 20 for high-risk patients and 1,148 for low-risk ones. It does not help long COVID, and it failed as post-exposure prophylaxis.

Evidence grade: Well established.

How it works

Drug class: SARS-CoV-2 main protease (3CLpro/Mpro) inhibitor co-packaged with ritonavir, an HIV-1 protease inhibitor used as a CYP3A pharmacokinetic booster

Nirmatrelvir blocks the SARS-CoV-2 main protease, so the virus cannot process its own proteins and cannot replicate properly. Ritonavir has no activity against the coronavirus; it is there purely to block the CYP3A enzyme that would otherwise break nirmatrelvir down, which keeps nirmatrelvir blood levels high enough to work. Because ritonavir blocks CYP3A for everything else as well, levels of many other medicines rise during the course. (Source 1)

Boxed warning

WARNING: SIGNIFICANT DRUG INTERACTIONS WITH PAXLOVID See full prescribing information for complete boxed warning. • PAXLOVID includes ritonavir, a strong CYP3A inhibitor, which may lead to greater exposure of certain concomitant medications, resulting in potentially severe, life-threatening, or fatal events. ( 4 , 5.1 , 7 ) • Prior to prescribing PAXLOVID: 1) Review all medications taken by the patient to assess potential drug-drug interactions with a strong CYP3A inhibitor like PAXLOVID and 2) Determine if concomitant medications require a dose adjustment, interruption, and/or additional monitoring. ( 7 ) • Consider the benefit of PAXLOVID treatment in reducing hospitalization and death, and whether the risk of potential drug-drug interactions for an individual patient can be appropriately managed. ( 5.1 , 7 , 14 )

(Source 2)

What it is used for

• EPIC-HR, in unvaccinated high-risk adults, found 0.77% hospitalisation or death versus 7.01% on placebo, a 6.32 percentage point absolute reduction. Omicron-era observational data in vaccinated and previously infected populations still show a benefit, but a much smaller absolute one, concentrated in older and higher-risk people. Evidence: established. (Source 3)
• EPIC-SR, the manufacturer's own trial in this group, missed its primary endpoint: symptoms took 12 days to settle on the drug and 13 days on placebo, and the difference in hospitalisation or death was not statistically significant. The approved indication is limited to people at high risk. Evidence: not-supported. (Source 4)
• A randomised trial of 2,736 asymptomatic household contacts found 2.6% (5-day course) and 2.4% (10-day course) developed symptomatic infection versus 3.9% on placebo, with no statistically significant reduction. The labelling states the drug is not approved for this. Evidence: not-supported. (Source 5)
• In the STOP-PASC randomised trial, 15 days of nirmatrelvir-ritonavir in 155 mostly vaccinated people with symptoms lasting a median of 17.5 months produced no statistically significant improvement in pooled symptom severity at 10 weeks. Evidence: not-supported. (Source 6)

Interactions

• St John's wort (Hypericum perforatum) (label): St John's wort is a strong CYP3A inducer and is an outright contraindication: it can cut nirmatrelvir and ritonavir blood levels enough to lose antiviral effect and select for resistance. The labelling also says the drug cannot be started immediately after stopping it, because enzyme induction persists. (Source 7)
• St John's wort - the measured size of the effect on a protease inhibitor (pharmacokinetic study): The nearest direct measurement comes from HIV medicine: in healthy volunteers St John's wort cut exposure to the protease inhibitor indinavir by 57% on average and its trough level by 81%. Nirmatrelvir has not been studied with St John's wort, so this is the mechanism shown in a related drug rather than a direct measurement. (Source 8)
• Red yeast rice (theoretical): Red yeast rice supplements work because they contain monacolin K, an HMG-CoA reductase inhibitor - the same mechanism as a statin. The labelling contraindicates lovastatin and simvastatin with this drug and tells prescribers to stop them before and during the course. Red yeast rice is not named in the labelling, so the concern is inferred from the shared mechanism rather than measured. (Source 9)
• Lovastatin and simvastatin (and, less strictly, atorvastatin) (label): Ritonavir raises statin levels sharply, which raises the risk of muscle injury. The labelling says lovastatin and simvastatin must be stopped at least 12 hours before the course, through it, and for 5 days afterwards. (Source 10)
• Amlodipine and other calcium channel blockers (label): Blocking CYP3A raises amlodipine levels, so blood pressure can fall too far and ankle swelling worsen during the course. This matters for anyone taking the amlodipine-benazepril combination. (Source 11)
• Other strong CYP3A inducers (rifampin, carbamazepine, phenytoin, phenobarbital) (label): These drugs do the same thing as St John's wort and are also contraindicated, because they can reduce nirmatrelvir levels enough to lose the antiviral effect. (Source 7)

Stopping it

• This is a fixed five-day course with no taper and no dependence or withdrawal syndrome described in the labelling. What does happen after stopping is rebound: in a prospective cohort with daily proctored testing, rebound occurred in both treated and untreated people but was more common after treatment. (Source 12)
• Medicines that had to be held for the course are not all restarted immediately: for lovastatin and simvastatin the labelling says to keep them stopped for five days after the course finishes, because ritonavir's effect on CYP3A outlasts the last dose. (Source 10)

What goes wrong

Altered taste and diarrhoea are the characteristic adverse effects, and in the high-risk trial serious adverse events were actually less common on the drug than on placebo because the drug prevented severe COVID-19. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 1,120 on drug, 1,126 on placebo.
• Who: Unvaccinated high-risk adults with COVID-19.
• How long: 5 days of treatment, adverse events through the treatment period.
• Result: Dysgeusia 5.6% vs 0.3%; diarrhoea 3.1% vs 1.6%; any adverse event 22.6% vs 23.9%; serious adverse events 1.6% vs 6.6%; discontinuation for adverse events 2.1% vs 4.2%.
• Funding: industry-funded (supported by Pfizer)

Dysgeusia (5.6% vs. 0.3%) and diarrhea (3.1% vs. 1.6%) occurred more frequently with nirmatrelvir plus ritonavir than with placebo.

Viral and symptom rebound after the course happens in treated and untreated people, but was two to three times more common in treated people in a prospective cohort with scheduled daily testing. (Source 12)

• Cohort study, Low certainty.
• Size: 669 analysed (443 treated, 226 untreated)
• Who: US outpatients with COVID-19 who chose for themselves whether to take the drug, August 2022 to December 2023.
• How long: 15 days of proctored rapid antigen tests and symptom surveys.
• Result: 15-day cumulative incidence of viral rebound 15.8% (70/443) vs 5.3% (12/226); symptom rebound 16.5% (73/443) vs 8.4% (19/226); among those who cleared by day 15, viral rebound 19.1% vs 7% and symptom rebound 47.7% vs 16.9% (both P<.001)
• Funding: not stated in the abstract.

Overall, 15-day cumulative incidence was higher in the NPR group than the control group for both viral (70/443, 15.8% vs 12/226, 5.3%) and symptom (73/443, 16.5% vs 19/226, 8.4%) rebound.

The interaction burden is not theoretical: in a real-world London referral service almost every treated patient had at least one potential interaction and 8% could not be given the drug at all because of them. (Source 13)

• Cohort study, Low certainty.
• Size: 208 patients who received nirmatrelvir/ritonavir.
• Who: Adults referred for COVID-19 antiviral therapy across a London region of 2.2 million people.
• How long: Service evaluation over the referral period.
• Result: 184 potential drug-drug interactions identified; 8% precluded use; 53% required active management; of those requiring management, 56% had no documented advice to hold therapy.
• Funding: not stated in the abstract.

Among 208 who received NMV/r therapy, we identified 184 potential DDIs, 8% precluded nirmatrelvir/ritonavir use, 53% required management, but 56% of these did not have documented advice to hold therapy.

The labelling carries a boxed warning that interactions through ritonavir's blockade of CYP3A can be severe, life-threatening or fatal. (Source 2)

• Official position, Certainty not rated.
• Size: Not applicable.
• Who: Anyone taking medicines cleared by CYP3A.
• How long: The 5-day course and, for enzyme recovery, several days after.
• Result: Boxed warning requiring a full medication review before prescribing.
• Funding: manufacturer-generated labelling (position of the FDA-approved label, DailyMed version read 2026-10-01)

PAXLOVID includes ritonavir, a strong CYP3A inhibitor, which may lead to greater exposure of certain concomitant medications, resulting in potentially severe, life-threatening, or fatal events.

Liver injury has been reported with the ritonavir component, and the drug can select for HIV protease inhibitor resistance in someone with undiagnosed or uncontrolled HIV. (Source 14)

• Official position, Certainty not rated.
• Size: Not quantified in the labelling.
• Who: People receiving ritonavir; people with undiagnosed or uncontrolled HIV-1 infection.
• How long: Not stated.
• Result: Transaminase rises, clinical hepatitis and jaundice reported; risk of HIV-1 protease inhibitor resistance.
• Funding: manufacturer-generated labelling (position of the FDA-approved label)

Hepatic transaminase elevations, clinical hepatitis, and jaundice have occurred in patients receiving ritonavir. ( 5.3 ) • HIV-1 Drug Resistance: PAXLOVID use may lead to a risk of HIV-1 developing resistance to HIV protease inhibitors

Severe skin hypersensitivity reactions including toxic epidermal necrolysis and Stevens-Johnson syndrome make the drug absolutely contraindicated in anyone who has had them to either ingredient. (Source 15)

• Official position, Certainty not rated.
• Size: Not quantified in the labelling.
• Who: People with a history of clinically significant hypersensitivity to nirmatrelvir or ritonavir.
• How long: Not applicable.
• Result: Absolute contraindication.
• Funding: manufacturer-generated labelling (position of the FDA-approved label)

PAXLOVID is contraindicated in patients with a history of clinically significant hypersensitivity reactions [e.g., toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome] to its active ingredients (nirmatrelvir or ritonavir) or any other components of the product.

What the evidence supports

In unvaccinated adults at high risk treated within three days of symptom onset, nirmatrelvir-ritonavir reduced COVID-19 hospitalisation or death by 6.32 percentage points in absolute terms. (Source 3)

• Randomized trial, Moderate certainty.
• Size: 2,246 randomised; 774 in the interim modified intention-to-treat analysis, 1,379 in the final one.
• Who: Symptomatic, unvaccinated, non-hospitalised adults with at least one risk factor for severe COVID-19, during the Delta period.
• How long: 5 days of treatment, 28 days of follow-up.
• Result: 0.77% (3 of 389) vs 7.01% (27 of 385); absolute difference -6.32 percentage points (95% CI -9.04 to -3.59), relative risk reduction 89.1%; final analysis -5.81 points (95% CI -7.78 to -3.84); all 13 deaths in the placebo group.
• Funding: industry-funded (supported by Pfizer)

the incidence was 0.77% (3 of 389 patients) in the nirmatrelvir group, with 0 deaths, as compared with 7.01% (27 of 385 patients) in the placebo group, with 7 deaths.

Across 47 Omicron-era cohort studies, treatment was associated with fewer hospitalisations and deaths, but the absolute benefit depends heavily on baseline risk. (Source 16)

• Meta-analysis, Low certainty.
• Size: 10,791,211 patients across 47 cohort studies.
• Who: Outpatients with COVID-19 from December 2021 onward, largely vaccinated or previously infected.
• How long: Varies by study; adjusted multivariable analyses only.
• Result: Adjusted RR 0.54 (95% CI 0.43-0.68) for all-cause hospitalisation, 0.45 (0.36-0.56) for COVID-19 hospitalisation, 0.30 (0.23-0.39) for all-cause mortality; number needed to treat to prevent one COVID-19 hospitalisation 1,148 at low risk, 84 at moderate risk, 20 at high risk.
• Funding: not stated in the abstract.

The estimated NNT to prevent a COVID-19 hospitalization for patients at low risk (0.16%), moderate risk (2.2%), and high risk (8.9%) of hospitalization based on a validated risk score were 1148, 84, and 20 respectively.

What the evidence does not support

In vaccinated people with a risk factor and unvaccinated people at standard risk, the drug did not shorten COVID-19 symptoms. (Source 4)

• Randomized trial, Moderate certainty.
• Size: 1,296 randomised; 1,288 analysed.
• Who: Adults with confirmed COVID-19 within 5 days of symptom onset, either fully vaccinated with at least one risk factor or unvaccinated at standard risk.
• How long: 5 days of treatment, 28 days of symptom diaries.
• Result: Median time to sustained alleviation of all targeted signs and symptoms 12 days vs 13 days, P = 0.60; hospitalisation or death 0.8% vs 1.6% (difference -0.8 percentage points, 95% CI -2.0 to 0.4)
• Funding: industry-funded (supported by Pfizer)

The median time to sustained alleviation of all targeted signs and symptoms of Covid-19 was 12 days in the nirmatrelvir-ritonavir group and 13 days in the placebo group (P = 0.60).

As post-exposure prophylaxis in household contacts, neither a 5-day nor a 10-day course significantly reduced symptomatic infection. (Source 5)

• Randomized trial, Moderate certainty.
• Size: 2,736 subjects randomised 1:1:1.
• Who: Asymptomatic adults who tested negative for SARS-CoV-2 and lived with a recently diagnosed symptomatic household member.
• How long: 5 or 10 days of treatment, 14 days of follow-up.
• Result: Symptomatic confirmed infection through day 14 in 2.6% (5-day), 2.4% (10-day) and 3.9% (placebo); no statistically significant risk reduction.
• Funding: industry-funded (manufacturer trial reported in the FDA-approved labelling)

The proportion of subjects who had events through Day 14 was 2.6% for the 5-day PAXLOVID regimen, 2.4% for the 10-day PAXLOVID regimen, and 3.9% for placebo. There was not a statistically significant risk reduction versus placebo for either the 5-day or 10-day PAXLOVID regimen.

A 15-day course did not improve long COVID symptoms in a randomised placebo-controlled trial. (Source 6)

• Randomized trial, Moderate certainty.
• Size: 155 participants (102 drug, 53 placebo-ritonavir)
• Who: Adults with moderate to severe post-acute sequelae of SARS-CoV-2 infection lasting 3 months or longer; nearly all vaccinated, median 17.5 months since infection.
• How long: 15 days of treatment, 10-week primary endpoint, 15-week trial.
• Result: No statistically significant difference in pooled severity across fatigue, brain fog, breathlessness, body aches, gastrointestinal and cardiovascular symptoms at 10 weeks; no difference in global impression scores or PROMIS measures.
• Funding: not stated in the abstract.

There was no statistically significant difference in the model-derived severity outcome pooled across the 6 core symptoms at 10 weeks between the NMV/r and PBO/r groups.

Where the evidence is mixed

In a national Omicron-era cohort, the benefit was clear in people aged 65 and over and absent in adults aged 40 to 64. (Source 17)

• Cohort study, Low certainty.
• Size: 109,254 eligible patients, 3,902 (4%) treated.
• Who: Clalit Health Services members aged 40 or over assessed as eligible for nirmatrelvir during the Omicron surge in Israel.
• How long: Omicron surge period, time-dependent Cox model.
• Result: Aged 65+: hospitalisation 14.7 vs 58.9 per 100,000 person-days, adjusted hazard ratio 0.27 (95% CI 0.15 to 0.49); death adjusted HR 0.21 (0.05 to 0.82). Aged 40-64: 15.2 vs 15.8 per 100,000 person-days, adjusted HR 0.74 (0.35 to 1.58); death adjusted HR 1.32 (0.16 to 10.75)
• Funding: not stated in the abstract.

Among patients 65 years of age or older, the rates of hospitalization and death due to Covid-19 were significantly lower among those who received nirmatrelvir than among those who did not. No evidence of benefit was found in younger adults.

Where the research disagrees

Whether the drug helps people who are vaccinated or at standard risk

• EPIC-SR investigators (Pfizer-funded randomised trial), Randomised, double-blind, placebo-controlled trial in 1,296 participants: "The median time to sustained alleviation of all targeted signs and symptoms of Covid-19 was 12 days in the nirmatrelvir-ritonavir group and 13 days in the placebo group (P = 0.60)." - no symptom benefit, and the hospitalisation difference was not significant (Source 4)
• Meta-analysis of Omicron-era observational studies (2026), Meta-analysis of 47 adjusted cohort studies, 10.8 million patients - observational, so confounding by indication and by healthy-user effects cannot be excluded: "N-R is associated with reduced hospitalization and death. Absolute risk reductions of hospitalization are small in low-risk patients but clinically meaningful in moderate- and high-risk patients." (Source 16)

Whether the drug benefits younger high-risk adults as much as older ones

• EPIC-HR (median age 46, unvaccinated), Randomised controlled trial in an unvaccinated Delta-era population: "the incidence was 0.77% (3 of 389 patients) in the nirmatrelvir group, with 0 deaths, as compared with 7.01% (27 of 385 patients) in the placebo group, with 7 deaths." (Source 3)
• Clalit Health Services cohort during the Omicron surge, Observational cohort of 109,254 eligible patients with time-dependent adjustment: "No evidence of benefit was found in younger adults." (Source 17)

How much

• Reference intake: There is no reference intake for a prescription antiviral; the dose is fixed and set by a prescriber. The approved US labelling gives 300 mg nirmatrelvir with 100 mg ritonavir twice daily for 5 days (position of the FDA-approved label, DailyMed version read 2026-10-01). (Source 18)
• Upper limit: There is no titration and no higher dose: the labelled maximum is the same as the labelled dose, 300 mg nirmatrelvir plus 100 mg ritonavir twice daily for 5 days, with a reduced dose in moderate renal impairment (position of the FDA-approved label). (Source 18)
• Studied: EPIC-HR gave 300 mg nirmatrelvir plus 100 mg ritonavir every 12 hours for 5 days, started within 3 days of symptom onset. (Source 3)
• Studied: The post-exposure prophylaxis trial gave the same dose every 12 hours for either 5 or 10 days to asymptomatic household contacts. (Source 5)
• Studied: The long COVID trial (STOP-PASC) gave 300 mg nirmatrelvir with 100 mg ritonavir twice daily for 15 days, against placebo plus ritonavir. (Source 6)

A common belief, and what the research shows

The belief: Paxlovid causes COVID rebound, so taking it makes you worse off.

What the research shows: Rebound is not unique to the drug. The prospective cohort that tested people daily found it in both groups - "Time to initial viral and symptom clearance was similar between groups" - but still more often after treatment, with 15-day viral rebound of 15.8% versus 5.3%. Separately, in the trial of high-risk unvaccinated people serious adverse events were lower on the drug than on placebo (1.6% vs 6.6%), because the drug prevented severe COVID-19: "The incidence of adverse events that emerged during the treatment period was similar in the two groups". Rebound is real and more common with treatment; it is a different question from whether the drug reduces hospitalisation and death.

Questions and answers

What is it?

It is a five-day course of two different tablets taken together for COVID-19. Nirmatrelvir is the antiviral, blocking the enzyme SARS-CoV-2 uses to cut its own proteins into working units. Ritonavir is an old HIV drug included only to stop the liver destroying nirmatrelvir too fast. It is licensed for adults at high risk of severe COVID-19. (Source 19)

What does it do in the body?

Nirmatrelvir stops the virus copying itself by blocking its main protease, which is why viral load falls faster on treatment. Ritonavir does nothing to the coronavirus; it blocks the CYP3A enzyme so nirmatrelvir survives long enough in the blood to work. That same enzyme blockade is what raises levels of many other medicines during the course. (Source 1)

Is it good or bad for you?

It depends almost entirely on how likely you are to end up in hospital. In unvaccinated high-risk adults it prevented about 6 hospitalisations or deaths per 100 treated. In the Omicron era the pooled estimate is a number needed to treat of 20 at high risk but 1,148 at low risk. In standard-risk and vaccinated people the manufacturer's own randomised trial found no symptom benefit. Against that sit altered taste, diarrhoea, rebound and a substantial interaction burden. (Source 16)

How do you get more of it?

This does not apply as it would for a nutrient. No food, drink or behaviour supplies nirmatrelvir or ritonavir; the only source is a prescription, and the course is a fixed dose rather than something titrated upward. Timing is what changes the effect: in the pivotal trial treatment had to start within three to five days of symptoms beginning. (Source 18)

If it is harmful, what reduces it?

The course ends after five days and the drug clears on its own; there is nothing to reduce or wash out. The one situation where levels of something need bringing down is the other way round - medicines whose levels this drug raises. The labelling handles that by stopping or dose-reducing the other drug before and during the course, and for some statins for five days afterwards. (Source 2)

Why might someone be low in it or missing it?

People who might benefit often do not get it. In a real-world London service, interactions with existing medicines ruled the drug out for 8% of those referred and required active management in 53%. The treatment window is also narrow - it has to start within days of symptoms - and in the Omicron-era cohort only 4% of eligible patients actually received it. (Source 13)

Which whole foods contain it or feed it?

No whole food contains either drug, and the labelling allows the tablets with or without food. The food and supplement issues are interactions rather than sources: St John's wort is contraindicated because it induces the enzyme the drug depends on, and red yeast rice is a statin by another name through its monacolin K content, which overlaps with the statins the labelling says to stop. (Source 7)

What happens if you do not have it?

Not taking it means taking the natural course of the infection. In the unvaccinated high-risk population of EPIC-HR that meant a 7.01% risk of COVID-19 hospitalisation or death within 28 days, and all 13 deaths in the trial were in the placebo group. In today's largely vaccinated populations the untreated risk is much lower, which is why the absolute benefit is smaller. (Source 3)

How can you test for it?

There is no test for the drug itself; what gets tested is the infection, because treatment depends on a confirmed diagnosis within days of symptom onset. A Cochrane review of 152 studies found rapid antigen tests detect on average 73.0% of infections in people with symptoms and only 54.7% in people without, while almost never giving a false positive (specificity 99.1% and 99.7%). Sensitivity was highest in the first week of symptoms, at 80.9%. (Source 20)

References

1. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, sections 12.1 and 12.2. 2026. Read the source
2. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, boxed warning: WARNING: SIGNIFICANT DRUG INTERACTIONS WITH PAXLOVID. 2026. Read the source
3. The New England journal of medicine. Oral Nirmatrelvir for High-Risk, Nonhospitalized Adults with Covid-19.. 2022. PMID 35172054, DOI 10.1056/nejmoa2118542. Read the source
4. The New England journal of medicine. Nirmatrelvir for Vaccinated or Unvaccinated Adult Outpatients with Covid-19.. 2024. PMID 38598573, DOI 10.1056/nejmoa2309003. Read the source
5. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 14.3 Post-Exposure Prophylaxis Trial. 2026. Read the source
6. JAMA internal medicine. Nirmatrelvir-Ritonavir and Symptoms in Adults With Postacute Sequelae of SARS-CoV-2 Infection: The STOP-PASC Randomized Clinical Trial.. 2024. PMID 38848477, DOI 10.1001/jamainternmed.2024.2007. Read the source
7. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 4 Contraindications (strong CYP3A inducers). 2026. Read the source
8. Lancet (London, England). Indinavir concentrations and St John's wort.. 2000. PMID 10683007, DOI 10.1016/s0140-6736(99)05712-8. Read the source
9. World journal of clinical cases. Red yeast rice with monacolin K for the improvement of hyperlipidemia: A narrative review.. 2025. PMID 40881894, DOI 10.12998/wjcc.v13.i27.105415. Read the source
10. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 7.3 (HMG-CoA reductase inhibitors). 2026. Read the source
11. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 7.3 Established and Other Potentially Significant Drug Interactions. 2026. Read the source
12. Interactive journal of medical research. COVID-19 Rebound in Nirmatrelvir Plus Ritonavir Treatment and Control Groups: Prospective Cohort Study.. 2026. PMID 42228900, DOI 10.2196/80263. Read the source
13. Expert review of anti-infective therapy. Nirmatrelvir/ritonavir: real world drug-drug interaction management experience.. 2024. PMID 39109469, DOI 10.1080/14787210.2024.2389884. Read the source
14. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, sections 5.3 and 5.4 Warnings and Precautions. 2026. Read the source
15. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 4 Contraindications. 2026. Read the source
16. Journal of general internal medicine. Effectiveness of Nirmatrelvir/Ritonavir for Outpatients in the Era of Omicron, Vaccination, and Previous Infection: A Meta-analysis.. 2026. PMID 42118190, DOI 10.1007/s11606-026-10494-4. Read the source
17. The New England journal of medicine. Nirmatrelvir Use and Severe Covid-19 Outcomes during the Omicron Surge.. 2022. PMID 36001529, DOI 10.1056/nejmoa2204919. Read the source
18. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, sections 2.2 and 2.3. 2026. Read the source
19. DailyMed, U.S. National Library of Medicine (FDA-approved labeling). PAXLOVID (nirmatrelvir and ritonavir) - FDA prescribing information, section 1 Indications and Usage. 2026. Read the source
20. The Cochrane database of systematic reviews. Rapid, point-of-care antigen tests for diagnosis of SARS-CoV-2 infection.. 2022. PMID 35866452, DOI 10.1002/14651858.cd013705.pub3. Read the source