Oxbryta is a brand-name prescription drug. It’s FDA-approved to treat sickle cell disease (SCD) in adults and in children ages 12 years and older.

People with SCD have an abnormal form of hemoglobin* called hemoglobin S. Usually, red blood cells are shaped like a disc. But hemoglobin S causes red blood cells to change into a sickle (crescent) shape. This is known as “sickling,” which can be painful. It may also lead to other serious health problems, such as blood clots and stroke.

The active drug in Oxbryta is voxelotor. Oxbryta belongs to a drug class called hemoglobin S polymerization inhibitors. (A drug class is a group of medications that work in a similar way.) Oxbryta treats SCD by preventing sickling.

Oxbryta comes as a tablet that you swallow. You’ll typically take it once per day. Oxbryta is available in one strength: 500 milligrams.

* Hemoglobin is a type of protein in red blood cells.

FDA approval

Oxbryta was approved by the Food and Drug Administration (FDA) in 2019. With this approval, Oxbryta became the first drug to treat SCD by targeting hemoglobin S.

Oxbryta received accelerated approval from the FDA. This means that the FDA approved Oxbryta based on information from early clinical trials. Typically, drugs are approved by the FDA after many clinical studies have been completed. But for some drugs, such as Oxbryta, the FDA may approve them before all studies are finished. This type of approval is typically given to drugs that treat conditions for which there aren’t many treatment options.

Effectiveness

For information about the effectiveness of Oxbryta, see the “Oxbryta for sickle cell disease” section below.

Oxbryta is available only as a brand-name medication. It’s not currently available in generic form.

A generic drug is an exact copy of the active drug in a brand-name medication. Generics usually cost less than brand-name drugs.

The Food and Drug Administration (FDA) approves prescription drugs such as Oxbryta to treat certain conditions. Oxbryta may also be used off-label for other conditions. Off-label drug use means using a drug for a purpose other than what it’s been approved for by the FDA.

Oxbryta is FDA-approved to treat sickle cell disease (SCD) in adults as well as in children ages 12 years and older.

SCD explained

SCD is a genetic (inherited) condition that affects hemoglobin, a protein in red blood cells. If you have SCD, you have an abnormal form of hemoglobin called hemoglobin S. Usually, red blood cells are shaped like a disc. But hemoglobin S causes red blood cells to change into a sickle (crescent) shape.

Symptoms of SCD may include:

  • fatigue (lack of energy)
  • jaundice (yellowing of your skin and the whites of your eyes)
  • pain and swelling in your fingers and toes

Sickled cells break down more quickly than other red blood cells. This can lead to anemia (low red blood cell counts).

SCD may cause other health complications, including:

Pain crisis and sickle cell crisis

Sickled cells can also stick to blood vessel walls and block the normal flow of blood and oxygen. When oxygen can’t get to parts of the body easily, it can cause a painful condition called a pain crisis. This crisis can be triggered by dehydration (water loss in the body) or sudden, extreme changes in temperature. For this reason, if you have SCD, you should drink plenty of water. And you should ease into new environments that have a sudden temperature change, such as a cold swimming pool.

If you have pain crisis plus any of the SCD complications described above in “Oxbryta for sickle cell disease,” it’s known as having a sickle cell crisis.

Effectiveness for SCD

Oxbryta has been found effective for treating SCD.

In a 24-week clinical study, 274 adults and children ages 12 years and older who had SCD took either Oxybryta or a placebo. (A placebo is a treatment with no active drug.) The study looked at the ability of Oxbryta to raise hemoglobin levels by at least 1 gram per deciliter (g/dL).

In this study, hemoglobin levels increased by at least 1 g/dL in:

  • 51.1% of people who took Oxbryta
  • 6.5% of people who took a placebo

Oxbryta and children

Oxbryta is FDA-approved to treat SCD in children ages 12 years and older. For more information, see “Oxbryta for sickle cell disease” above.

Oxbryta is FDA-approved to treat sickle cell disease (SCD) in adults and in children ages 12 years and older.

SCD is a genetic (inherited) condition that affects hemoglobin, a protein in red blood cells. People with SCD have an abnormal form of hemoglobin called hemoglobin S. Usually, red blood cells are shaped like a disc. But hemoglobin S causes red blood cells to change into a sickle (crescent) shape. This is known as “sickling,” which can be painful. It may also lead to other serious health problems, such as blood clots and stroke.

Oxbryta has a unique mechanism of action for treating SCD. (“Mechanism of action” refers to the way a drug works in the body.) Oxbryta is the first drug that targets hemoglobin S to prevent the process of sickling.

How long does it take to work?

Oxbryta starts working right away to treat SCD. You may not notice the drug working in your body. But you should have fewer symptoms or complications of SCD after you start taking Oxbryta. They may also be less severe.

Oxbryta can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Oxbryta. These lists do not include all possible side effects.

For more information about the possible side effects of Oxbryta, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you’d like to notify the FDA about a side effect you’ve had with Oxbryta, you can do so through MedWatch.

Mild side effects

Mild side effects of Oxbryta can include:*

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Oxbryta. To learn about other mild side effects, talk with your doctor or pharmacist or view Oxbryta’s patient information.
† For more information about this side effect, see “Side effect details” below.

Serious side effects

Serious side effects from Oxbryta aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Serious side effects may include:

* For more information about this side effect, see “Side effect details” below.

Side effects in children

Oxbryta is approved for use in children ages 12 years and older with sickle cell disease (SCD). The side effects of Oxbryta in children are similar to those in adults. See the “Mild side effects” and “Serious side effects” sections above for more information on these side effects.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail on certain side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Oxbryta. In clinical studies, fewer than 1% of adults and children ages 12 years and older had an allergic reaction to Oxbryta. The percentage of people who may have had an allergic reaction to the placebo (a treatment with no active drug) isn’t known.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Oxbryta, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or you think you’re having a medical emergency.

Headache

Taking Oxbryta can cause headache in some people. In clinical studies of adults and of children ages 12 years and older, Oxbryta was compared with a placebo.

In these studies, headache was experienced by:

  • 26% of those who took Oxbryta
  • 22% of those who took a placebo

The length of time that headaches lasted for people taking Oxbryta or the placebo isn’t known.

If you have bothersome headaches while taking Oxbryta, talk with your doctor. They may be able to suggest ways to ease this side effect.

Diarrhea

Diarrhea is a possible side effect of Oxbryta. In clinical studies of adults and of children ages 12 years and older, diarrhea was experienced by:

  • 20% of those given Oxbryta
  • 10% of those given a placebo

If you have diarrhea while taking Oxbryta, talk with your doctor. They can suggest ways to treat this side effect.

Rash

Some people may have a rash while taking Oxbryta.

In clinical studies, Oxbryta was compared with a placebo in adults and in children ages 12 years and older. The results showed that:

  • 14% of those who used Oxbryta had a rash
  • 10% of those who used a placebo had a rash

If you experience a rash while using Oxbryta, talk with your doctor. They can recommend ways to treat this side effect.

The Oxbryta dosage your doctor prescribes will depend on several factors. These include:

  • other medical conditions you may have
  • other medications you take

The following information describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Drug forms and strengths

Oxbryta comes as a tablet that you swallow. It’s available in one strength: 500 milligrams (mg).

Dosage for sickle cell disease

The typical dosage for treating sickle cell disease (SCD) is 1,500 mg once per day. This is a total of three 500-mg tablets.

Your doctor may prescribe a different dosage depending on several factors, including whether or not you have liver disease.

Children’s dosage

Oxbryta is approved to treat SCD in children ages 12 years and older. The dosage of Oxbryta used for children is the same as the adult dosage.

For more information, see the “Dosage for sickle cell disease” section above.

Dosage questions

Below are answers to some questions you may have about taking Oxbryta.

What if I miss a dose?

If you miss a dose of Oxybryta, skip your missed dose. You should keep taking Oxybryta on your normal schedule the next day. Don’t take extra doses to make up for your missed dose. This can raise your risk for side effects from Oxbryta. (For more information, see the “Oxbryta side effects” section above.)

To help make sure that you don’t miss a dose, try using a medication reminder. This can include downloading a reminder app or setting an alarm or timer on your phone. A kitchen timer can also work.

Will I need to use this drug long term?

Oxbryta is meant to be used as a long-term treatment. If you and your doctor determine that Oxbryta is safe and effective for you, you’ll likely take it long term.

Other drugs are available that can treat sickle cell disease (SCD). Some may be a better fit for you than others. If you’re interested in finding an alternative to Oxbryta, talk with your doctor. They can tell you about other medications that may work well for you.

Alternatives for SCD

Other drugs that may be used to treat SCD include:

Oxbryta may be taken with other medications to treat sickle cell disease (SCD).

Hydroxyurea (Droxia) is a drug that’s been used to treat SCD for many years. Your doctor may recommend that you try treatment with hydroxyurea before you start taking Oxbryta. They may have you keep using hydroxyurea while you’re taking Oxbryta. But Oxbryta doesn’t have to be taken with hydroxyurea. Clinical studies have found that Oxbryta helps treat SCD when used with or without hydroxyurea.

You may use other medications with Oxbryta for problems related to SCD. For example, if you have anemia, your doctor may prescribe iron while you’re taking Oxbryta. If you have pain from SCD, your doctor may suggest nonsteroidal anti-inflammatory drugs or other pain relievers.

If you have questions about taking other medications with Oxbryta, talk with your doctor.

There are no known interactions between Oxbryta an alcohol.

But drinking alcohol can cause dehydration (low fluid levels in your body). If you have sickle cell disease (SCD), dehydration can trigger a sickle cell crisis (a sudden episode of severe pain). You may need to limit the amount of alcohol you drink while you’re taking Oxbryta for SCD.

If you drink alcohol, talk with your doctor. They can tell you how much alcohol is safe to drink during your Oxbryta treatment.

Oxbryta can interact with several other medications. It can also interact with certain supplements as well as certain foods.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works, while others can increase the number of side effects or make them more severe.

Oxbryta and other medications

Below are examples of medications that can interact with Oxbryta. This section does not contain all drugs that may interact with Oxbryta.

Before taking Oxbryta, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also, tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Oxbryta and certain CYP3A4 inhibitors, including fluconazole

An enzyme called CYP3A4 breaks Oxbryta down in your body. CYP3A4 inhibitors are a group of drugs that inhibit (block) this enzyme from working. Using these drugs with Oxbryta can increase the level of Oxbryta in your blood. This can increase your risk for side effects from Oxbryta. (For more information about side effects, see the “Oxbryta side effects” section above.)

Examples of drugs that block the action of CYP3A4 include:

Before you start using Oxbryta, tell your doctor about any drugs you’re taking. They can tell you if any drugs you’re taking are CYP3A4 inhibitors. If you must use one of these drugs, your doctor may suggest a different treatment while you’re taking Oxbryta. Or they may adjust your Oxbryta dosage.

Oxbryta and strong and moderate CYP3A4 inducers

CYP3A4 is an enzyme that breaks Oxbryta down in your body. Strong and moderate CYP3A4 inducers are a group of drugs that induce (increase) the activity of this enzyme. This can lower the level of Oxbryta in your blood and make the drug less effective for treating your condition.

Examples of strong and moderate CYP3A4 inducers include:

Before you start treatment with Oxbryta, tell your doctor about all the medications you take. They can determine if any of the drugs are strong or moderate CYP3A4 inducers. If they are, your doctor may adjust your dosage of Oxbryta.

Oxbryta and midazolam

Taking Oxbryta with midazolam (Versed) can raise the level of midazolam in your blood. This can increase your risk for side effects from midazolam, such as sleepiness, confusion, or trouble breathing.

Before you start using Oxbryta, tell your doctor if you take midazolam. They may adjust your dosage of midazolam or recommend a treatment other than midazolam.

Oxbryta and herbs and supplements

The manufacturer of Oxbryta hasn’t reported any specific interactions with herbs or supplements. But you should still check with your doctor or pharmacist before using any of these products while taking Oxbryta.

Products that may make Oxbryta less effective are described below.

Oxbryta and St. John’s wort

Taking the herb St. John’s wort could lower the level of Oxbryta in your blood. This could cause Oxbryta to be less effective.

While you’re taking Oxbryta, talk with your doctor or pharmacist before using any herbs or supplements.

Oxbryta and foods

There aren’t any foods that have been specifically reported to interact with Oxbryta. But you may need to avoid eating certain foods while you’re taking Oxbryta. One of these foods is described below.

Oxbryta and grapefruit

CYP3A4 is an enzyme that breaks Oxbryta down in your body. Grapefruit can inhibit (block) CYP3A4 from breaking down Oxbryta. So, eating grapefruit or drinking grapefruit juice while taking Oxbryta may increase the level of Oxbryta in your blood. This could raise your risk for side effects from Oxbryta. (To learn about possible side effects, see the “Oxbryta side effects” section above.)

If you have questions about eating certain foods while you’re taking Oxbryta, talk with your doctor.

Oxbryta and lab tests

Taking Oxbryta can affect certain lab tests that measure hemoglobin levels. (Hemoglobin is a protein in red blood cells.) Make sure your doctor knows you’re taking Oxbryta before they order a hemoglobin test. They may adjust your Oxbryta schedule so they can get an accurate measurement of your hemoglobin levels.

As with all medications, the cost of Oxbryta can vary. To find current prices for Oxbryta in your area, check out GoodRx.com.


The cost you find on GoodRx.com is what you may pay without insurance. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Before approving coverage for Oxbryta, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure if you’ll need to get prior authorization for Oxbryta, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Oxbryta, or if you need help understanding your insurance coverage, help is available.

Global Blood Therapeutics Inc., the manufacturer of Oxbryta, offers a program called GBT Source Solutions. For more information and to find out if you’re eligible for support, call 833-GBT-4YOU (833-428-4968) or visit the program website.

Generic version

Oxbryta isn’t available in a generic form. A generic drug is an exact copy of the active drug in a brand-name medication. Generics tend to cost less than brand-name drugs.

You should take Oxbryta according to your doctor’s or healthcare provider’s instructions.

Oxbryta comes as a tablet that you swallow.

When to take

You’ll likely take Oxbryta once per day. Try to take your doses around the same time every day. This helps make sure you have a steady level of the drug in your body so it can work effectively.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include downloading a reminder app or setting an alarm or timer on your phone. A kitchen timer can also work.

Taking Oxbryta with food

You can take Oxbryta with or without food. But eating grapefruit or drinking grapefruit juice while taking Oxbryta may increase the level of Oxbryta in your blood. To learn more, see “Oxbryta and grapefruit” in the “Oxbryta interactions” section above.

If you have questions about consuming grapefruit products while you’re taking Oxbryta, talk with your doctor.

Can Oxbryta be crushed, split, or chewed?

No, you shouldn’t crush, split, or chew Oxbryta. You should swallow Oxbryta tablets whole.

It isn’t known if it’s safe to take Oxbryta while pregnant. The drug hasn’t been studied in pregnancy.

But sickle cell disease (SCD) can increase the risk of miscarriage (pregnancy loss). It can also increase the risk of premature birth or having a baby with a low birth weight. For this reason, Oxbryta use during pregnancy may cause complications. But these may not be caused by the drug itself.

If you’re pregnant or planning to become pregnant, talk with your doctor. They can tell you about the risks and benefits of taking Oxbryta while pregnant.

Oxbryta and fertility

Oxbryta isn’t known to affect fertility (the ability to conceive a child). But SCD can cause fertility problems. Therefore, some people who take Oxbryta may have trouble conceiving a child. But this may not necessarily be caused by Oxbryta.

Talk with your doctor if you have questions about conceiving a child while taking Oxbryta.

It’s not known if Oxbryta is safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Oxbryta.

For more information about taking Oxbryta during pregnancy, see the “Oxbryta and pregnancy” section above.

You shouldn’t breastfeed while using Oxbryta. The drug hasn’t been studied to see if it passes into breast milk. But if you’re taking Oxbryta and breastfeeding, it’s possible that your child could have side effects from the drug.* For this reason, you shouldn’t breastfeed while using Oxbryta or for at least 2 weeks after taking your last dose of the drug.

In animal studies, Oxbryta has been found in the milk of lactating animals who were given the drug. But what happens in animal studies doesn’t always predict what will happen in humans.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before using Oxbryta. They may suggest a treatment option other than Oxbryta.

* For more information on these side effects, see the “Oxbryta side effects” section above

Here are answers to some frequently asked questions about Oxbryta.

Will Oxbryta cure my sickle cell disease?

No, Oxbryta won’t cure your sickle cell disease (SCD). The only known cure for SCD is a stem cell or bone marrow transplant.

Even though Oxbryta isn’t considered a cure, clinical studies have found the drug to be effective for treating SCD. (To learn more, see “Effectiveness for SCD” in the “Oxbryta for sickle cell disease” section above.)

Talk with your doctor if you have questions about options for treating your SCD.

Will I need to take other drugs with Oxbryta?

Possibly. Oxbryta may be taken with other medications to treat SCD. For example, your doctor may prescribe hydroxyurea (Droxia) or nonsteroidal anti-inflammatory drugs with Oxbryta. But Oxbryta doesn’t have to be taken with other medications.

For more information, see the “Oxbryta use with other drugs” section above. You can also talk with your doctor if you have questions about taking other medications with Oxbryta.

Do I need to have a certain genotype to take Oxbryta?

No, you don’t have to have a certain genotype (genetic makeup) of SCD to take Oxbryta. Clinical studies have found Oxbryta to be effective for treating this condition in people who had different sickle cell genotypes.

Will Oxbryta interfere with any regular lab tests I get for SCD?

Yes, taking Oxbryta can affect certain lab tests that measure hemoglobin levels. (Hemoglobin is a protein in red blood cells.)

Before your doctor orders a hemoglobin test, make sure they know if you’re taking Oxbryta. They may adjust your Oxbryta schedule so they can get a true measurement of your hemoglobin levels.

If you have any questions about how taking Oxbryta may affect hemoglobin testing, talk with your doctor.

Is Oxbryta a long-term treatment?

Yes, Oxbryta is meant to be used as a long-term treatment. If you and your doctor determine that Oxbryta is safe and effective for you, you’ll likely take it long term.

Before taking Oxbryta, talk with your doctor about your health history. Oxbryta may not be right for you if you have certain medical conditions or other factors that affect your health. These include:

  • Allergic reaction. If you’ve had an allergic reaction to Oxbryta or any of its ingredients, you shouldn’t take Oxbryta. Ask your doctor about which other medications are better options for you.
  • Pregnancy. It isn’t known if it’s safe to take Oxbryta during pregnancy. For more information, see the “Oxbryta and pregnancy” section above.
  • Breastfeeding. You shouldn’t breastfeed while using Oxbryta. For more information, see the “Oxbryta and breastfeeding” section above.

Note: For more information about the potential negative effects of Oxbryta, see the “Oxbryta side effects” section above.

Don’t use more Oxbryta than your doctor recommends. For some drugs, doing so may lead to unwanted side effects or overdose.

What to do in case you take too much Oxbryta

If you think you’ve taken too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

When you get Oxbryta from the pharmacy, the pharmacist will add an expiration date to the label on the bottle. This date is typically 1 year from the date they dispensed the medication.

The expiration date helps guarantee that the medication is effective during this time. The current stance of the Food and Drug Administration (FDA) is to avoid using expired medications. If you have unused medication that has gone past the expiration date, ask your pharmacist if you can still use it.

Storage

How long a medication remains good can depend on many factors, including how and where you store it.

You should store Oxbryta tablets at or below 86°F (30°C) in a tightly sealed container away from light. Avoid storing this medication in areas where it could get damp or wet, such as bathrooms. You shouldn’t keep Oxbryta tablets in an area where children can reach them.

Disposal

If you no longer need to take Oxbryta and have leftover medication, it’s important to dispose of it safely. This helps prevent others, including children and pets, from taking the drug by accident. It also helps keep the drug from harming the environment.

This article provides several useful tips on medication disposal. You can also ask your pharmacist for information about how to dispose of your medication.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.