It’s been two years since COVID-19 first came on the scene, and most people believe that we still have a long way to go to fight it. In December of 2021, the FDA approved two new antiviral treatments that are able to treat mild to moderate cases of COVID-19.

Both of these pills are recommended only for people who have a high risk of developing severe illness due to COVID-19. They are known as molnupiravir and Paxlovid, and while they have a lot of similarities, there are also differences between the two. This article should help you when you’re trying to decide which of the two medications you should take.

What Is Molnupiravir?

Molnupiravir is an oral antiviral pill that is able to treat mild to moderate COVID-19. It is manufactured by Merck and is authorized for adults ages 18 and over who are at high risk of severe COVID-19. This being said, the FDA has recommended the molnupiravir be used only when no other COVID-19 treatments are available. Molnupiravir is a nucleoside analog that stops the COVID-19 virus from copying itself. However, it accomplishes this in a completely different way than Paxlovid does.

Molnupiravir looks like the genetic building blocks that the virus uses to copy itself. Once you take the medication, the virus then inserts molnupiravir into its genetic material. The result? The virus is then unable to copy itself. Molnupiravir can actually lower the risk of high-risk people getting COVID-19 by about 30%. You have to take the medication orally twice daily for five full days, and for the best results, it needs to be started within five days of when you first start feeling the COVID-19 symptoms.

What Is Paxlovid?

When deciding between molnupiravir vs. Paxlovid, it’s best to compare both the differences and the similarities between the two medications. As opposed to molnupiravir, Paxlovid is actually a combination of two different medications: nirmatrelvir and ritonavir. Just as with molnupiravir, Paxlovid must be taken by mouth twice daily for five days and should be started within five days of the first symptoms.

It is made by Pfizer and was the first oral medication to receive emergency use authorization (EUA) from the FDA, and it treats mild to moderate symptoms. Paxlovid can be used by anyone 12 years of age and older, as long as they weigh at least 88 pounds.

Currently, it is only recommended for people who are at high risk of developing severe COVID-19, which means that older adults and people with certain medical conditions are the ones for which it will do the most good. Both nirmatrelvir and ritonavir are protease inhibitors. The former stops the virus from copying itself, and the latter helps slow the breakdown of nirmatrelvir. So in essence, ritonavir helps make nirmatrelvir more effective against COVID-19.

What You Need to Know About Both Pills

To help you learn the similarities and differences between Paxlovid and molnupiravir, below are some additional facts that will help.

Doses and Packaging

Molnupiravir comes with a total of 40 capsules. You’ll take four capsules twice a day (every 12 hours) for five full days. You have to take them whole and you can take them with or without food. Just as with an antibiotic, you have to complete all five days of doses in order for the medication to be effective.

Paxlovid comes with a total of 30 tablets. You take three pills twice a day -- two nirmatrelvir tablets and one ritonavir tablet -- for a full five days. Again, they must be taken whole and taken for a total of five days in order to do their job. They can be taken with or without food.

Their Effectiveness

Both Paxlovid and molnupiravir are most effective when taken within five days of showing symptoms of COVID-19. In fact, this factor was proven in clinical trials, and the effectiveness of each of these medications is lower if they are taken after the five-day timeframe.

When tested in clinical trials, Paxlovid was 90% effective in preventing hospitalization or death due to COVID-19, at least when it comes to high-risk people. If you have a standard risk of severe illness, Paxlovid has shown an effective rate of around 70%.

Molnupiravir, on the other hand, lowered the risks of COVID-19-related death or hospitalizations by about 30% in high-risk people. This could be one of the reasons why the FDA recommends taking this particular medication only if you do not have access to other COVID-19 treatments. Still, both medications significantly lower the risks of death or hospitalization due to COVID-19, especially when compared to taking no medication at all.

Possible Interactions

All prescription and over-the-counter medications have possible interactions with other medications, and Paxlovid and molnupiravir are no different. While not all interactions can be listed here, below are some of the medications that could interact with these two COVID-19 medications.


Some of these interactions will make the Paxlovid medication less effective, while others will make it too plentiful in your body. Some of these medications include:

● Some medicines for heart rhythm problems (e.g., amiodarone)

● Some medicines for reducing cholesterol (e.g., simvastatin)

● Some medicines for controlling seizures (e.g., carbamazepine)

● St. John’s Wort (an OTC herbal product)

● Some forms of birth control (e.g., those that contain ethinyl estradiol)

● Ergot medications, e.g., dihydroergotamine mesylate

● Sildenafil, when used to treat pulmonary arterial hypertension

● Colchicine

● Lurasidone

Again, this is not an inclusive list of medications that may interact with Paxlovid. This is why it is absolutely crucial for you to discuss all of the medications you’re taking, both prescription and over-the-counter, with your doctor before you even consider taking this medicine. You cannot be too careful when disclosing this information to your physician.


Unlike Paxlovid, molnupiravir isn’t known to interact with any medications. That being said, it is still very important for you to discuss all of your prescription and OTC medications with your doctor before taking molnupiravir. Why? Because this issue is still being studied, which means that the information about possible interactions could change by the time you read this article. Nevertheless, it is still good to know that molnupiravir currently doesn’t interact with any medicines.

Possible Side Effects

Both Paxlovid and molnupiravir have potential side effects; some are mild and some are serious. As far as the mild side effects go, both of these COVID-19 medications have side effects that include diarrhea, changes in taste, muscle aches and high blood pressure (Paxlovid); and diarrhea, nausea, and dizziness (molnupiravir). In addition, some of the more unique side effects of each of these medications include:


Paxlovid is hard on the kidneys and liver, so if you have any problems with these two organs, they might get worse when taking Paxlovid. Furthermore, Paxlovid contains two protease inhibitors, which are often used to treat HIV. If you are being treated for HIV, it may become resistant to your current HIV medications if you take Paxlovid.

If you have HIV or any problems with either your kidneys or liver, especially if you’re on medication for any of these conditions, make sure that you let your doctor know before taking Paxlovid.


Potential problems with molnupiravir center on reproductive issues. If you’re pregnant, you cannot take the medicine at all. If you are able to get pregnant, you’ll need to use reliable birth control while taking molnupiravir and for four days after your very last dose. If you’re a male who is with someone who could get pregnant, you should use a condom while taking molnupiravir and for a minimum of three months after you take your last dose of the medication.

These extra precautions are necessary because the medication has been shown to harm unborn babies or cause a miscarriage, and because it is thought it could also affect sperm.

As mentioned earlier, people under the age of 18 cannot take molnupiravir because it can affect the development of cartilage and bone in younger people. This is why you’ll want to discuss everything about your health and medications with your doctor before taking either one of the COVID-19 drugs.

The Costs of the Medications

The exact costs of these medications are difficult to pin down, mostly because they are both so new and because the costs with insurance included haven't been established. Originally, the prices reported were $530 for a course of Paxlovid and $700 for a round of molnupiravir. Since then, however, both Merck and Pfizer have claimed that the recent costs will be much lower, so you can check online about both of these medications.

That being said, these two antiviral treatments are set to be shipped to the U.S. sometime during 2022, so no one knows what the exact costs of each will be. Once they arrive, that should change and it should be simple to do a quick Internet search and find out how much they each cost.


Both Paxlovid and molnupiravir are prescription drugs used to treat COVID-19, and both have their own pros and cons. If you’re interested in taking one, talk to your healthcare provider regarding which one is right for you.