What Is Ritonavir?

Ritonavir (brand name Norvir) is a prescription medication classified as a protease inhibitor and pharmacokinetic enhancer. It is used to treat HIV-1 infection in combination with other antiretroviral drugs and to boost the effectiveness of other medications by slowing their breakdown in the body. Ritonavir is also a key ingredient in Paxlovid, the antiviral combination used to treat COVID-19.

Ritonavir was first approved by the FDA in 1996 and is manufactured by AbbVie under the brand name Norvir. Generic versions are now available from multiple manufacturers.

What Is Ritonavir Used For?

Ritonavir has three main uses:

1. HIV Treatment

As part of a combination antiretroviral regimen, Ritonavir helps suppress HIV by blocking the virus's protease enzyme. This prevents the virus from making copies of itself. Ritonavir is almost always used with other HIV medications — it is not effective on its own.

2. Pharmacokinetic Booster

This is Ritonavir's most common role today. At low doses (100-200 mg), Ritonavir inhibits an enzyme called CYP3A4 in your liver. This slows down how quickly your body breaks down other protease inhibitors, keeping their blood levels high enough to work effectively. Drugs commonly boosted with Ritonavir include Darunavir (Prezista) and Atazanavir (Reyataz).

3. COVID-19 Treatment (as Part of Paxlovid)

Ritonavir is combined with nirmatrelvir in Paxlovid. In this combination, Ritonavir boosts nirmatrelvir levels so it can effectively fight the SARS-CoV-2 virus. The typical course is 100 mg of Ritonavir twice daily for 5 days.

To understand the science behind these uses, see our guide on how Ritonavir works.

How Is Ritonavir Taken?

Ritonavir comes in three forms:

• Tablets (100 mg) — The most common form. Swallow whole with food. Do not crush, split, or chew.
• Oral powder (100 mg packets) — Can be mixed with soft food like applesauce or pudding, or stirred into liquid. Must be consumed within 2 hours of mixing.
• Oral solution (80 mg/mL) — A liquid form, sometimes used for patients who have difficulty swallowing tablets.

Dosage

• As HIV treatment (full dose): 600 mg twice daily, usually increased gradually over 2 weeks to reduce side effects.
• As a booster: 100-200 mg once or twice daily, depending on the medication being boosted.
• As part of Paxlovid: 100 mg twice daily for 5 days.
• Children (over 1 month): Dosing is based on body surface area — typically 350-400 mg/m² twice daily.

Important: Always take Ritonavir with meals. Food improves absorption and reduces stomach side effects. Your doctor may start you on a lower dose and increase gradually to help your body adjust.

Who Should Not Take Ritonavir?

Ritonavir is not safe for everyone. You should not take it if you:

• Have a known allergy to Ritonavir or any of its ingredients.
• Are taking certain medications that interact dangerously with Ritonavir. These include Amiodarone, Flecainide, Propafenone, ergot alkaloids (like Ergotamine), Simvastatin, Lovastatin, Pimozide, Triazolam, oral Midazolam, and Sildenafil when used for pulmonary hypertension.
• Are taking St. John's wort, which can dramatically reduce Ritonavir levels and make it ineffective.

Ritonavir requires extra caution in people with liver disease (especially hepatitis B or C), diabetes, hemophilia, or high cholesterol. It can also reduce the effectiveness of hormonal birth control.

For a complete list of interactions, read our drug interactions guide.

How Much Does Ritonavir Cost?

Cost depends on whether you use brand-name Norvir or a generic version:

• Brand (Norvir): $200-$500 for 30 tablets without insurance.
• Generic Ritonavir: $34-$100 for 30 tablets with a discount card.

Most insurance plans, including Medicare Part D and Medicaid, cover Ritonavir. The federal AIDS Drug Assistance Program (ADAP) covers most or all costs for uninsured patients with HIV/AIDS.

If you are paying out of pocket, there are ways to save:

• Use a discount card from GoodRx, SingleCare, or RxSaver.
• Ask about the AbbVie Patient Assistance Foundation.
• Check if you qualify for ADAP or the Ryan White Program.

For more details, see our complete savings guide.

Common Side Effects

The most frequently reported side effects include diarrhea, nausea, vomiting, stomach pain, headache, taste changes, and tingling in the hands or feet. Most improve over time, especially when Ritonavir is taken with food and the dose is increased gradually.

Final Thoughts

Ritonavir is a well-established medication that plays an important role in both HIV treatment and COVID-19 care. Whether you take it as a booster, part of Paxlovid, or as full-dose HIV therapy, understanding how to take it properly and what to watch for can help you get the most from your treatment.

If you need help finding Ritonavir at an affordable price, visit MedFinder to search pharmacies and compare costs in your area.