6 mins read

Overview: Welireg is used to treat certain types of cancer or tumors. It works to slow tumor growth by blocking a specific protein. Common side effects include low levels of red blood cells (anemia) and tiredness. Tell your health care provider right away if you have shortness of breath, a fast heartbeat, confusion, or tiredness that keeps getting worse. These could be signs of low oxygen levels. Welireg comes as a tablet that you swallow.

Uses

What is Welireg used for?

Welireg (belzutifan) is commonly used for the following conditions.

  • Certain types of tumors in people with von Hippel-Lindau (VHL) disease, a rare inherited disorder
  • A type of kidney cancer (clear cell renal cell carcinoma)
  • A type of tumor that forms inside the adrenal glands (pheochromocytoma) or outside the adrenal glands (paraganglioma)

Welireg may also be used for other conditions as determined by your health care provider.

How does Welireg work (mechanism of action)?

Welireg is a hypoxia-inducible factor (HIF) inhibitor. It works by blocking a protein called HIF-2α. Normally, this protein helps cells respond when oxygen levels are low. But in some tumors, too much HIF-2α builds up and turns on genes that help tumors grow and make new blood vessels. By blocking HIF-2α, Welireg can help slow or stop tumor growth.

How is Welireg supplied (dosage forms)?

Brands and other names

  • Welireg

Dosage forms and strengths

  • 40 mg oral tablets

How should I store Welireg?

Welireg should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of Welireg?

The most common side effects of Welireg are listed below. These side effects may vary depending on the condition that is being treated. Tell your health care provider if you have any of these side effects that bother you.

  • Low red blood cell levels (see below)
  • Changes in liver and kidney function tests
  • Increased blood sugar levels and other abnormal blood tests
  • Tiredness
  • Muscle or joint pain
  • Headache
  • Shortness of breath
  • Dizziness
  • Nausea

There may be other side effects of Welireg that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of Welireg?

While less common, the most serious side effects of Welireg are described below, along with what to do if they happen.

Severe Allergic Reactions. Welireg may cause allergic reactions, which can be serious. Stop taking Welireg and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives, which can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Low Red Blood Cell Levels. Welireg may cause anemia, which is when you have low levels of red blood cells. It can sometimes be severe. Some people may need a blood transfusion during Welireg treatment. Tell your health care provider if you have any of the following symptoms of anemia.

  • Unusual weakness or tiredness
  • Cold hands and feet
  • Fast or abnormal heartbeat or chest discomfort
  • Pale or yellowish skin
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Shortness of breath

Low Oxygen Levels. Welireg may cause low oxygen levels (hypoxia), which can sometimes be severe. When your body does not get enough oxygen, your brain and other organs may not work well and could become damaged. Your health care provider may check your oxygen levels before and during Welireg treatment. Some people may need oxygen treatment while taking Welireg. Tell your health care provider if you have any of the following symptoms of low oxygen levels.

  • Shortness of breath
  • Fast heartbeat
  • Changes in the color of your skin
  • Confusion
  • Cough or wheezing

Warnings & Precautions

Who should not take Welireg?

Allergies to Ingredients. People who are allergic to any of the following should not take Welireg.

  • Belzutifan
  • Welireg
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Welireg.

What should I know about Welireg before using it?

Do not take Welireg unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share Welireg with other people, even if they have the same condition as you. It may harm them.

Keep Welireg out of the reach of children.

Do not chew, cut, or crush Welireg. Swallow each tablet whole.

Take Welireg at the same time each day. If you throw up after taking Welireg, do not take another dose. Just take your regular dose the next day at the usual time.

Your health care provider may do blood tests before you start Welireg and during treatment. It is important to attend all appointments so your health care provider can make sure it is safe for you to take Welireg.

Welireg may make it hard for you to get pregnant or get your partner pregnant. If you have concerns, talk to your health care provider.

What should I tell my health care provider before taking Welireg?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if Welireg is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Low red blood cell levels (anemia)
  • Lung or breathing problems

Other Medicines and Supplements. Welireg may interact with other medicines and supplements. Before taking Welireg, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Genetic Variation. Some people’s bodies may not break down (metabolize) Welireg as well because of certain differences in their genes. This is known as being a “poor metabolizer” and may lead to higher levels of the medicine in the body and a greater risk of side effects. Before taking Welireg, tell your health care provider if you have any problems breaking down medicines or have been told you are a poor metabolizer. Your health care provider can let you know if Welireg is safe for you.

Pregnancy. Welireg may cause harm to a fetus. You should not get pregnant while taking Welireg. Your health care provider may do a test to make sure you are not pregnant before starting treatment. If you can get pregnant, you should use nonhormonal birth control (such as condoms or a diaphragm) during Welireg treatment and for one week after your last dose. Welireg may make some hormonal birth control methods (such as the pill, patch, or vaginal ring) not work as well. If you can get a partner pregnant, you should use birth control (such as condoms) while taking Welireg and for one week after your last dose. Talk to your health care provider about effective birth control options. Tell your health care provider right away if you are pregnant, think you might be pregnant, or plan to become pregnant.

Breastfeeding. It is not known if Welireg passes into breast milk. You should not breastfeed while taking Welireg and for one week after your last dose. Tell your health care provider if you are breastfeeding or plan to breastfeed.

How can I get more information about Welireg?

For more information about Welireg, you can visit the drugmaker’s website at www.welireg.com or call them at 888-516-8947.

Interactions

Does Welireg interact with foods or drinks?

There are no known interactions between Welireg and foods or drinks.

It is unknown if drinking alcohol will affect Welireg.

Does Welireg interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. 

In particular, make sure that you discuss if you are using a birth control pill, patch, vaginal ring, implant, injection, or intrauterine device (IUD) that contains hormones.

Some other medicines may alter the blood levels of Welireg, and vice versa. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with Welireg. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much Welireg?

If you or someone else has taken too much Welireg, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of Welireg?

If you miss a dose, take it as soon as you remember that same day. Then take your next dose the next day at your usual time. Do not take double or extra doses.

Look up another drug