Voxelotor is used to treat sickle cell disease (an inherited blood disease) in adults and children 12 years of age and older. Voxelotor is in a class of medications called hemoglobin S (HbS) polymerization inhibitors. It works by helping hemoglobin (a protein in red blood cells) to hold onto more oxygen and to stop red blood cells from becoming misshapen.

Side Effects Of Voxelotor

Voxelotor may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • diarrhea
  • stomach pain
  • nausea
  • fever

Some side effects can be serious. If you experience any of these symptoms, stop taking voxelotor and call your doctor immediately or get emergency medical treatment:

  • rash, hives, shortness of breath, or facial swelling

Voxelotor may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before taking voxelotor:

  • tell your doctor and pharmacist if you are allergic to voxelotor, any other medications, or any of the ingredients in voxelotor tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: certain antifungals such as fluconazole (Diflucan), itraconazole (Onmel, Sporanox), or ketoconazole; carbamazepine (Tegretol); clarithromycin (Biaxin, in Prevpac); diltiazem (Cardizem, Cartia, Diltzac, Taztia); erythromycin (E-Mycin, Erythrocin); medications to treat HIV including didanosine (Videx), efavirenz (Sustiva, in Atripla), nelfinavir (Viracept), ritonavir (Norvir, in Kaletra), or saquinavir (Fortovase, Invirase); nefazodone; phenobarbital; phenytoin (Dilantin); rifabutin (Mycobutin); rifampin (Rifadin, Rimactane, in Rifamate, in Rifater); or oral steroids such as dexamethasone, methylprednisolone (Medrol), and prednisone (Rayos). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor what herbal products you are taking, especially St. John’s wort.
  • tell your doctor if you have or have ever had liver disease.
  • tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking voxelotor, call your doctor.
  • tell your doctor if you are breast-feeding. Do not breastfeed while taking voxelotor and for 2 weeks after your final dose.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking voxelotor.

Dosage Of Voxelotor

Voxelotor comes as a tablet to take by mouth. It is usually taken once daily with or without food. Take voxelotor at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take voxelotor exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.


Keep all appointments with your doctor.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking voxelotor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.