Reviewed on 11/2/2022

What Is Ritonavir and How Does It Work?

Ritonavir is a prescription medication used in combination with other antiretroviral agents for the treatment of HIV infection. 

  • Ritonavir is available under various brand names: Norvir

What Are Side Effects Associated with Using Ritonavir?

Common side effects of Ritonavir include:

  • nausea,
  • vomiting,
  • stomach pain,
  • diarrhea,
  • numbness or tingling in the hands or feet or around the mouth,
  • weakness,
  • tiredness,
  • rash, and
  • changes in the shape or location of body fat (especially in your arms, legs, face, neck, breast, and waist)

Serious side effects of Ritonavir include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • skin sores,
  • fast or pounding heartbeats,
  • sweating,
  • mouth sores,
  • fever,
  • sore throat,
  • burning eyes,
  • skin pain,
  • red or purple skin rash with blistering and feeling,
  • irregular heartbeats,
  • lightheadedness,
  • easy bruising,
  • unusual bleeding (nose, mouth, vagina, or rectum),
  • purple or red pinpoint spots under your skin,
  • pain in your side or lower back,
  • blood in the urine,
  • painful or difficult urination,
  • increased thirst,
  • increased urination,
  • hunger,
  • dry mouth,
  • fruity breath odor,
  • loss of appetite,
  • upper stomach pain (that may spread to the back),
  • nausea,
  • vomiting,
  • dark urine,
  • yellowing of the skin or eyes (jaundice),
  • night sweats,
  • swollen glands,
  • cold sores,
  • cough,
  • wheezing,
  • diarrhea,
  • weight loss,
  • trouble speaking or swallowing,
  • problems with balance or eye movement,
  • weakness,
  • prickly feeling,
  • swelling in the neck or throat (enlarged thyroid),
  • menstrual changes, and
  • impotence

Rare side effects of Ritonavir include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are Dosages of Ritonavir?

Adult and pediatric dosage


  • 100 mg


  • 100 mg

Oral solution

  • 80 mg/mL

Oral powder

  • 100 mg/packet

HIV Infection

Adult dosage

  • 300 mg orally every 12 hours initially; increase by 100 mg every 12 hours to 600 mg orally every 12 hours  over 5 days as tolerated
  • Use as a booster with another protease inhibitor: 100-400 mg orally every day or divided every 12 hours.

Pediatric dosage

  • Age below 1 month: Safety and efficacy not established
  • Age above 1 month: 250 mg/m² orally every 12 hours  initially; increase by 50 mg/m² every 2-3days to 350-400 mg/m² every 12 hours; not to exceed 600 mg every 12 hours  
  • Adolescents: 300 mg orally every 12 hours initially; increase by 100 mg every 12 hours to 600 mg orally every 12 hours over 5 days as tolerated

Oral solution

  • Do not administer to neonates before the postmenstrual age of 44 weeks
  • Contains 43.2% alcohol and 26.57% propylene glycol; total amounts of alcohol and propylene glycol from all medicines that are to be given to pediatric patients aged 1-6 months should be taken into account in order to avoid toxicity from these excipients
  • Measure the dose with a calibrated oral syringe

Oral powder

  • Used only for dosing increments of 100 mg
  • Should not be used for doses less than 100-mg or for incremental doses between 100 mg intervals (use oral solution for these doses)

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Ritonavir?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Ritonavir has severe interactions with at least 35 other drugs.
  • Ritonavir has serious interactions with at least 162 other drugs.
  • Ritonavir has moderate interactions with at least 383 other drugs.
  • Ritonavir has minor interactions with at least 72 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Ritonavir?


Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Ritonavir?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Ritonavir?”


  • Do not administer with antacids; separate from didanosine by 2 hr
  • Potent inhibitor of CYP3A4 (but also induces CYP450 enzymes)
  • Monitor: monthly neurologic evaluation
  • Risk of immune reconstitution syndrome if used in combination with other antiretroviral drugs
  • Risks of hemolytic anemia and hyperbilirubinemia if used in combination with other antiretroviral drugs
  • Capsules must be kept refrigerated
  • Allergic reactions have been reported and include anaphylaxis, toxic epidermal necrolysis, Stevens-Johnson Syndrome, bronchospasm, and angioedema; discontinue treatment if severe reactions develop
  • Consider the drug-drug interaction potential to reduce the risk of serious or life-threatening adverse reactions
  • Oral solution not for administration in preterm neonates in the immediate postnatal period; may cause toxicity; safety and efficacy not established
  • Monitor liver function before and during therapy, especially in patients with underlying hepatic disease, including hepatitis B and hepatitis C, or marked transaminase elevations; fatalities resulting from hepatic reactions reported
  • Fatalities resulting from pancreatitis reported; suspend therapy as clinically appropriate
  • PR interval prolongation reported in some patients; cases of second and third-degree heart block reported; use with caution with patients with preexisting conduction system disease, ischemic heart disease, cardiomyopathy, underlying structural heart disease, or when administering with other drugs that may prolong the PR interval
  • Total cholesterol and triglycerides elevations may occur; monitor prior to therapy and periodically thereafter
  • Patients may develop new onset or exacerbations of diabetes mellitus, hyperglycemia
  • Patients may develop redistribution/accumulation of body fat
  • Spontaneous bleeding may occur; additional factor VIII may be required

Pregnancy & Lactation

  • Advise pregnant women not to use oral solution during pregnancy owing to its alcohol content
  • Inform patients that there is an antiretroviral (ARVs) pregnancy registry that monitors fetal outcomes of pregnant women exposed to ARVs 1–800–258–4263
  • Follow current CDC/WHO recommendations for HIV treatment during pregnancy
  • Lactation
    • Excreted in human milk
    • The CDC recommends that HIV-1-infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection, risk of developing viral resistance (in HIV-positive infants), and risk of serious adverse reactions

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