Covid 19

Which Oral Medicine is Best for Treating COVID-19? Molnupiravir Or Paxlovid

  • January 15, 2023
  • 4 mins read

Key Highlights:

  • Molnupiravir (Lagevrio) and Paxlovid (consists of a couple of medications: nirmatrelvir and ritonavir) are 2 oral antiviral treatments that are authorized for the treatment of mild to moderate SARS-CoV-2 COVID-19. These COVID-19 oral pills are only authorized for those with an increased risk of developing severe disease.
  • Both these antivirals are for oral administration and are taken by mouth twice a day for five days. Treatment with Molnupiravir and Paxlovid should be started within five days of the onset of the first symptoms.
  • Diarrhea, nausea, and dizziness are the most commonly reported side effects of Molnupiravir.
  • Changes in taste, diarrhea, high blood pressure, and muscle aches are the most commonly reported side effects of Paxlovid.

Since 2020, the CORONAVIRUS outbreak has affected all segments of the population. But also in this time, health officials have made several medical breakthroughs in order to help combat SARS-CoV-2 infections.

At the end of December 2021, the federal agency the Department of Health and Human Services (FDA) authorized a couple of oral COVID-19 medications named: Molnupiravir (Lagevrio) and Paxlovid (nirmatrelvir/ritonavir). Both were the first oral treatment authorized to help prevent mild-moderate Coronavirus disease from worsening.

About Molnupiravir:

Molnupiravir is an oral antiviral medicine, formulated in the form of a pil and authorized to treat mild-moderate COVID-19. Manufactured by Merck, the drug Molnupiravir received emergency use authorization shortly after Paxlovid. This antiviral medicinal product is authorized for adults ages 18 years and older that are at an increased risk of developing severe COVID-19 infection. Although, health officials recommended taking this medicine only if other therapies are not available or appropriate.

Mechanism of Action of Molnupiravir for COVID-19:

Designated as a nucleoside analog antiviral, Molnupiravir inhibits the COVID-19 virus from making copies of itself, but it is a completely different way than medicine Paxlovid.

Molnupiravir medicine looks like the genetic building blocks that the  SARS-CoV-2 COVID-19 virus uses to copy itself. So when you are on treatment with this medication, the virus mistakenly inserts molnupiravir into its genetic material. During this time, the virus can’t make a copy of itself.

About Paxlovid:

Manufactured by Pfizer, Paxlovid is a combination of 2 antivirals: nirmatrelvir and ritonavir. It was the first oral medicinal product to receive EUA for treating mild to moderate COVID-19 infection.

This medicine is authorized for adults and children ages 12 years and older who weigh at least 40 kg. Paxlovid is currently only suggested for those at increased risk of developing serious COVID-19. Increased-risk individuals include older adults and all those with certain medical complications.

Mechanism of Action of Paxlovid for COVID-19:

Both drugs in Paxlovid, nirmatrelvir and ritonavir, worka in a combination to treat COVID-19. Both fall under the same class of drugs: Protease Inhibitors (PIs).

In Paxlovid, the first medicine Nirmatrelvir blocks the virus that causes COVID-19 infection from copying itself. The virus relies on a protein in bodies named protease to copy itself. For the nonce, Nirmatrelvir blocks this protein from functioning so the virus can’t use it to expand. 

On the other hand, second medicine named Ritonavir helps resist the breakdown of nirmatrelvir. This helps nirmatrelvir exist in the body at greater levels for a longer time span. In other words, ritonavir help make nirmatrelvir comparatively more effective against COVID-19 infection than it would be on its own.

Dosage of Molnupiravir and Paxlovid:

Both medicines have some similarities when it comes to how they are administered. The significant difference lies in how many pills you take at once.

Paxlovid is typically supplied as a prepackaged carton that contains 30 tablets. For each dose, 2 nirmatrelvir tablets and 1 ritonavir tablet are taken. These 3 tablets of nirmatrelvir and ritonavir should be taken orally twice daily for 5 consecutive days. Swallow these pills completely. It is not advisable to split, chew, or crush them.

Molnupiravir prescription is typically supplied with 40 capsules. Four capsules should be taken by mouth (orally) twice in a day (every 12 hours) for 5 consecutive days. The molnupiravir capsules should be swallowed whole. It is not advisable to open or crush the capsules.

Treatment with both medicines should be initiated within 5 days of when an individual first starts observing COVID-19 signs and symptoms. Both COVID-19 oral pills can be taken either with or without food. Health officials suggest to finish taking every single dose of the drug prescribed to you to help the treatment be as promising as possible.

Potency of Molnupiravir and Paxlovid for Treating COVID-19:

As per several clinical trials, molnupiravir reduced the risk of COVID-19 hospitalization or death by approximately 30% in an increased-risk population in initial studies. This significant difference in potency may be one of the reasons health officials suggest using molnupiravir medicine only if other treatments aren’t available or appropriate.

On the other hand, Paxlovid was approximately 90% promising at preventing hospitalization or death because of COVID-19 in increased-risk individuals. As per other studies, the benefits of Paxlovid are predominantly evident for older adults.

Please note that these levels of potency were noted when study participants started treatment with Molnupiravir or Paxlovid within 5 days of first experiencing signs and symptoms. The drugs’ effectiveness is lower if the drugs are initiated after this time span.

Side Effects of Molnupiravir and Paxlovid:

The probable side effects for both Molnupiravir and Paxlovid were mild for most individuals in clinical trials.

The most commonly reported molnupiravir side effects are: 

  • Diarrhea
  • Nausea
  • Dizziness

The most commonly reported paxlovid side effects include:

  • Changes in taste 
  • Diarrhea
  • High blood pressure
  • Muscle aches

Molnupiravir and Paxlovid Combination for COVID-19: 

The combination of Molnupiravir and Paxlovid hasn’t been evaluated for any indication, including treating SARS-CoV-2 COVID-19. An interaction between both these medicines isn’t listed by their manufacturer. But, because of the lack of research about whether it is safe or useful, this combination isn’t recommended.


Both Molnupiravir and Paxlovid are currently available oral COVID-19 medications, which are authorized for treating high-risk individuals with mild to moderate signs and symptoms. Treatment with both these medications should be started within 5 days of the first clinical symptoms of COVID-19. Medicines Paxlovid and molnupiravir have several similarities, but the significant difference lies in how potent these drugs are at treating the SARS-CoV-2 Virus (COVID-19). It’s feasible for symptoms to come back after completing either COVID-19 oral medicine. But rebound signs/symptoms are frequent when individuals consider or opt no treatment. In case you’ve recently tested positive for SARS-CoV-2 Virus (COVID-19), talk to your health specialist to see if either antiviral medicinal product is an option for you.