Oxbryta (Voxelotor) - Oral

What Is Oxbryta?

Oxbryta (voxelotor) is approved by the Food and Drug Administration (FDA) to treat sickle cell disease (SCD). It contains the active drug voxelotor and belongs to a drug class called hemoglobin S polymerization inhibitors.

SCD is a hereditary disorder in which the individual has an abnormal form of hemoglobin called hemoglobin S. Hemoglobin S causes red blood cells to change from a normal disc shape into a sickle (crescent) shape known as sickling. Oxbryta has a unique mechanism of action that targets hemoglobin S to prevent the process of sickling. It helps hemoglobin to hold more oxygen and stops red blood cells from changing shape.

Oxbryta is a prescription drug available as oral tablets.

Drug Facts

Generic Name: Voxelotor

Brand Name(s): Oxbryta

Drug Availability: Prescription

Therapeutic Classification: Hemoglobin S (HbS) polymerization inhibitors

Available Generically: No

Controlled Substance: N/A

Administration Route: Oral

Active Ingredient: Voxelotor

Dosage Form(s): Tablet (oral tablet, oral tablet for suspension)

What Is Oxbryta Used For?

Oxbryta is used to prevent sickle cell anemia in adults and children aged 4 and older. In November 2019, Oxbryta received its first global approval to treat sickle cell disease in the US. Oxbryta was granted accelerated approval based on the phase III HOPE trial results. Continued approval of this drug for sickle cell anemia may be subject to verification and description of its clinical benefits in the confirmatory trials.

Sickle cell disease is an inherited blood disease that affects more than 100,000 individuals in the United States and over 20 million people around the world. The disease causes a shortened life span characterized by the production of abnormal, sickle-shaped hemoglobin (a red protein that transports oxygen in your blood), anemia, vaso-occlusion (blockage) of blood vessels, and tissue damage. Oxbryta is a recently approved novel treatment for sickle cell disease.

Oxbryta (Voxelotor) Drug Information: A person with sickle cells

Verywell / Zoe Hansen

How to Take Oxbryta

Read the prescription label carefully before taking medicine. Ask your pharmacist or healthcare provider if you have any questions. 

  • Oxbryta comes as an oral tablet and a tablet for oral suspension (ex., to be mixed with water), usually taken once a day or as your healthcare provider prescribes. 
  • Take the oral tablet with or without food. 
  • Swallow the oral tablets whole. Do not split, chew, or crush the oral tablets.
  • If you take Oxbryta tablets for oral suspension: see the detailed Instructions for use on how to prepare and take your dose. You must mix the Oxbryta tablets for oral suspension in a room temperature clear drink, such as water or clear soda, right before taking it. Do not swallow whole, cut, crush, or chew the tablets for oral suspension.
  • Do not take more, less, or more often than prescribed. 
  • Take medicine regularly and do not skip doses to get the most benefit from it. 

Contact your healthcare provider if your symptoms do not improve or get worse.


Keep the tablets in the original container. Store at room temperature away from heat and moisture. Do not store this medication in the bathroom.

Keep all medication locked out of sight and reach of children. To protect young children from poisoning, always lock the safety cap so that young children can not open them easily. 

Discard all unused and expired drugs, but do not pour them down the drain or in the toilet. Ask your pharmacist or healthcare provider about the best ways to dispose of this medicine. And check out medication take-back programs in your area.

If you plan to travel with Oxbryta, get familiar with your final destination's regulations. In general, be sure to make a copy of your Oxbryta prescription. If possible, keep your medication in its original container from your pharmacy with your name on the label. If you have any questions about traveling with your medicine, be sure to ask your pharmacist or healthcare provider.

Off-Label Uses

Oxbryta may be used off-label for other conditions. Ask your healthcare provider about any other use of this medicine.

How Long Does Oxbryta Take to Work?

Oxbryta starts working immediately after taking it. It will help improve the symptoms and complications of the disease. However, Oxbryta is a long-term treatment. You may need to take it as long as prescribed by your healthcare provider.

What Are the Side Effects of Oxbryta?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Oxbryta may cause some common side effects, such as:

Contact your healthcare provider if these side effects do not go away or worsen.

Severe Side Effects

Some severe side effects of Oxbryta are:

  • Hypersensitivity reactions cause symptoms such as rash, hives, shortness of breath, or swelling of the face.

If you experience these symptoms, stop taking Oxbryta and call your healthcare provider or get emergency medical help.

Report Side Effects

Oxbryta may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Oxbryta Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For sickle cell disease:
      • Adults and children 12 years of age and older—1,500 milligrams (mg) once a day.
      • Children younger than 12 years of age—Use and dose must be determined by your doctor.


The following modifications (changes) should be kept in mind when using Oxbryta:

Severe allergic reaction: Oxbyta may cause some severe allergic reactions. Don't use this product if you are allergic to voxelotor on any other product component.

Pregnancy: In animal studies, Oxbryta did not have adverse (bad) developmental effects on the fetus. We don't know enough about the safety and effectiveness of Oxbryta in pregnant people and on their unborn fetuses. Discuss with your healthcare provider if you are or plan to become pregnant and weigh the benefits and risks of taking Oxbryta during your pregnancy.

Breastfeeding: Due to the potential risk for severe adverse reactions in the breastfed child, breastfeeding is not recommended during treatment with Oxbryta and at least two weeks after the last dose. Talk with your healthcare provider if you plan to breastfeed, to weigh the benefits and risks of taking Oxbryta while nursing, and the different ways available to feed your baby.

Adults over the age of 65 years: Clinical studies haven't included a large enough number of people in this age group to see whether they respond differently from younger adults.

Children: The safety and effectiveness of Oxbryta have been established in children 4 and older. The drug's safety has not been established in children younger than 4.

Other modifications: Dose reduction may be required in severe hepatic impairment (severe liver issues) to avoid the increased concentration of Oxbryta.

Administration modification: Do not take St. John’s wort with Oxbryta.

Missed Dose

If you accidentally forgot your Oxbryta dose, take it as soon as you remember. However, if it's already close to your next scheduled dose, skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Try to find ways to help yourself remember to routinely take the medication that works for you. If you miss too many doses, Oxbryta might be less effective at treating sickle cell disease.

Overdose: What Happens If I Take Too Much Oxbryta?

If you think that you're experiencing an overdose or life-threatening symptoms, seek immediate medical attention.

What Happens If I Overdose on Oxbryta?

If you think you or someone else may have overdosed on Oxbryta, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Oxbryta, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

This medicine may cause allergic reactions. Tell your doctor right away if you have a rash or itching skin, chest pain, fever or chills, mild swelling of the face, trouble breathing, or unusual tiredness or weakness while using this medicine.

Do not change your dose or stop taking this medicine without checking first with your doctor.

Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Oxbryta?

Oxbryta is contraindicated in people with a known history of a severe drug hypersensitivity reaction to voxelotor or any of its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Severe allergic symptoms may include:

  • Generalized rash
  • Urticaria (itchy rashes on the skin)
  • Shortness of breath
  • Facial swelling
  • Eosinophilia (a higher than average level of disease-fighting white blood cells)

Oxbryta is also contraindicated in breastfeeding people during treatment and for two weeks after the last dose.

What Other Medications Interact With Oxbryta?

Oxbryta may interact with certain drugs. Coadministration of these drugs (taking them together) may require monitoring and dose modification to reduce side effects and improve efficacy.

Strong or moderate CYP3A4 inducers (drugs that impact how the liver metabolizes them) may decrease Oxbryta blood concentrations and reduce how well it works. Avoid taking Oxbryta with strong or moderate CYP3A4 inducers. Your healthcare provider might also increase your dose of Oxbryta if you're unable to avoid using CYP3A4 inducers.

Oxbryta should not be used with sensitive CYP3A4 substrates (a particular enzyme in the liver and intestine). If you can't avoid CYP3A4 substrates, your healthcare provider may consider reducing your dose.

Avoid grapefruit and grapefruit juice while taking Oxbryta.

Use the following medicines with caution when taking with Oxbryta. Your healthcare provider may need to adjust the doses:

Oxbryta administration may interfere with high-performance liquid chromatography (HPLC) lab results for Hb subtypes (HbA, HbS, and HbF, mutant forms of hemoglobin). Only use HPLC 10 days after stopping Oxbryta.

Talk with your pharmacist or healthcare provider for more detailed information about medication interactions with Oxbryta.

And be sure to talk with your healthcare provider about any other medicines you take or plan to take, including over-the-counter, nonprescription products, vitamins, herbs, or plant-based medicines.

What Medications Are Similar?

Sickle cell disease can be treated using hematopoietic stem cell transplantation and gene therapy. But these treatment approaches are not available to a broader population. Until relatively recently, the FDA has approved a few drugs to reduce the severity of the disease, such as Oxbryta.

Other drugs used to treat SCD include:

  • Adakveo (crizanlizumab)
  • Endari (L-glutamine)
  • Droxia (hydroxyurea)

Oxbryta may be taken with Droxia (hydroxyurea) to treat SCD.

Talk to your healthcare provider if you’re interested in finding an alternative to Oxbryta. 

Frequently Asked Questions

  • What is Oxbryta?

    Oxbryta is a prescription drug containing voxelotor as an active ingredient. It belongs to the class of hemoglobin S polymerization inhibitors approved to treat sickle cell disease.

  • How Oxbryta treats sickle cell disease?

    Oxbryta prevents an abnormal form of hemoglobin called hemoglobin S. Hemoglobin S causes sickling (change from a normal disc to a crescent) of hemoglobin.

  • Do I have to take Oxbryta for a long-term?

    Oxbryta is generally a long-term treatment. Your healthcare provider will determine the duration of treatment depending on your condition and response to the drug. 

  • What are the side effects of Oxbryta?

    Common side effects of Oxbryta are headache, fever, diarrhea, and stomach pain. But it may cause severe hypersensitivity reactions. You should not take Oxbryta if you are allergic to any of its ingredients.

  • What dietary precautions should I take while taking Oxbryta?

    Do not eat grapefruit or drink grapefruit juice with this medicine. Grapefruit may increase the level of this medication in your blood.

How Can I Stay Healthy While Taking Oxbryta?

Sickle cell disease affects millions of people. It is an inherited disease that causes complications and reduces the life span. The FDA approved some drugs that improve the choice of appropriate drug therapy, medication combinations, and affordability. When used alone or in combination, these medicines can prevent or decrease organ damage and improve outcomes in SCD therapy. 

  • Oxbryta is not a cure for sickle cell disease, but it improves the symptoms of the disease.
  • Keep regular appointments with your healthcare provider to monitor the progress or improvement of your condition.
  • Avoid certain foods such as grapefruit or herbal products such as St. John's wort. These may increase the Oxbryta levels in the blood, leading to increased side effects.
  • Take Oxbryta as long as it's been prescribed, and do not quit without asking your healthcare provider.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Food and Drug Administration. Oxbryta (voxelotor) label.

  3. Vichinsky E, Hoppe CC, Ataga KI, et al. A phase 3 randomized trial of voxelotor in sickle cell disease. N Engl J Med. 2019;381(6):509-519. doi:10.1056/NEJMoa1903212.

  4. National Heart Lung and Blood Institute. What is sickle cell disease?

  5. Rai P, Ataga KI. Drug therapies for the management of sickle cell disease. F1000Res. 2020;9:F1000 Faculty Rev-592. doi:10.12688/f1000research.22433.1