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Paxlovid is an oral antiviral medication developed by Pfizer for the treatment of symptomatic moderate to severe COVID-19.

Last Modified: 08 May 2024

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What is Paxlovid? 

Paxlovid is an oral antiviral medication developed by Pfizer for the treatment of symptomatic moderate to severe COVID-19. It contains the active ingredients nirmatrelvir and ritonavir, which work together to inhibit the virus's ability to replicate within the body. 

Quick breakdown of the drug’s structure: Paxlovid is made up of two antiviral drugs. Nirmatrelvir is a protease inhibitor specifically designed to target the SARS-CoV-2 virus, while ritonavir is a pharmacokinetic enhancer that increases the effectiveness of nirmatrelvir by slowing its breakdown in the body. 

Global Name

Generic name: Nirmatrelvir/Ritonavir 
Brand names: Paxlovid 


What is Paxlovid used for? 

Paxlovid is used to treat symptomatic COVID-19 in individuals who are at risk for developing severe illness. The drug helps to reduce the viral load, thereby mitigating the severity of the disease. It is not used as a substitute for vaccination against COVID-19. 

How do you use Paxlovid? 

Availability: Paxlovid is available in tablet form. 

Dosage information: 

  • Adults and adolescents (12 years and older weighing at least 40 kg): 300 mg of nirmatrelvir (two 150 mg tablets) with 100 mg of ritonavir (one 100 mg tablet) taken together orally twice daily for 5 days. 

Are the following suitable to take the drug: 

  • Children: Not recommended for children under 12 years or weighing less than 40 kg. 
  • Adults: Approved for adults who meet the criteria. 
  • Elderlies: Suitable for elderly patients, but with consideration for potential drug interactions and comorbidities. 
  • Pregnancy and Lactation: Should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Caution is advised when administering to breastfeeding mothers. 

Is there anyone who can’t take Paxlovid? 

  • Children under 12 years or weighing less than 40 kg 
  • Adults with severe renal or hepatic impairment without dose adjustment 
  • Elderlies with contraindicating conditions 
  • Patients with known allergies to the active ingredients or excipients 
  • Patients taking certain other medications that have serious interactions with Paxlovid 

Any warnings and precautions 

  • Paxlovid should can be taken with or without food. 
  • Avoid consuming grapefruit or grapefruit juice during treatment with Paxlovid, as it can increase medication levels in your blood and subsequent side-effects. 

Interactions and contraindications of the drug 

  • Paxlovid should not be taken with certain other medications, such as those metabolized by the enzyme CYP3A or those that prolong the QT interval. 
  • It is not recommended for patients being treated for Hepatitis C infection with glecaprivir/pivrentasvir. Monitor drug levels in HIV patients being treated with drug combinations containing ritonavir to mitigate adverse events. 

Side Effects

Common side effects include altered taste, diarrhea, high blood pressure, and muscle aches. Severe side effects are rare but can include allergic reactions. 

Pharmacist Tips

  • Store Paxlovid at room temperature, away from moisture and heat. 
  • Handle the medication with clean, dry hands, and follow the prescribed dosing schedule closely. 


Where is Paxlovid available in Hong Kong?

Paxlovid is a prescription medication that can be prescribed by healthcare providers then bought at pharmacies.


How to get Paxlovid in Hong Kong?

No, Paxlovid is not available over-the-counter. It requires a prescription from a healthcare provider.

How quickly should Paxlovid be taken after a positive COVID-19 test?

Paxlovid should be started as soon as possible after a positive COVID-19 test, if medically assessed to be at risk for development of severe illness, and within five days of symptom onset.

Can Paxlovid be taken by people with liver or kidney issues?

Paxlovid should be used with caution in people with renal or hepatic impairment, and dose adjustments may be necessary.

What should I do if I miss a dose of Paxlovid?

If you miss a dose of Paxlovid, take it as soon as you remember. If it is almost time for the next dose, skip the missed dose and continue with your regular dosing schedule. Do not take extra medicine to make up for the missed dose. 


This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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