Caprelsa (vandetanib) is an oral targeted therapy used to treat adults with medullary thyroid cancer that can’t be removed by surgery or has spread to other parts of the body. It’s typically taken by mouth once a day, and side effects include diarrhea, rash, nausea, and headaches. It can also cause an irregular heart rhythm (QT prolongation) that can lead to dizziness, fainting, or even death. Because of this risk, Caprelsa (vandetanib) is only available under a restricted distribution program called a Risk Evaluation and Mitigation Strategy (REMS) program.
Medullary thyroid cancer that can’t be treated with surgery or has spread to other areas of the body
Caprelsa (vandetanib) is a targeted therapy called a tyrosine kinase inhibitor, meaning it stops specific kinases from working. Kinases are enzymes or proteins that send signals to cells, helping them grow.
Caprelsa (vandetanib) works by blocking these signals in cancer cells, which in turn reduces their blood supply, slows their growth, and hinders their ability to survive.
Source: DailyMed
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Bleeding gums
blindness
blistering, crusting, irritation, itching, or reddening of the skin
blurred vision
body aches or pain
chest pain or tightness
chills
cloudy urine
confusion
coughing up blood
difficulty with breathing or swallowing
dizziness
ear congestion
fainting
headache
increased menstrual flow or vaginal bleeding
increased sensitivity of the skin to sunlight
irregular heartbeat, recurrent
loss of voice
muscle cramps in the hands, arms, feet, legs, or face
nervousness
nosebleeds
numbness and tingling around the mouth, fingertips, or feet
paralysis
pounding in the ears
prolonged bleeding from cuts
red or black, tarry stools
red or dark brown urine
seizures
severe sunburn
slow or fast heartbeat
stomach cramps or pain
stuffy or runny nose
tenderness
trouble breathing
unusual tiredness or weakness, severe
watery or bloody diarrhea
Less common
Blue lips, fingernails, or skin
dilated neck veins
extreme tiredness or weakness
infection from breathing foreign substance into the lungs
irregular heartbeat
irregular, fast or slow, or shallow breathing
lightheadedness
swelling of the face, fingers, feet, or lower legs
Rare
decreased urine output
indigestion
loss of appetite
pains in the stomach, side, or abdomen, possibly radiating to the back
yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Belching
blemishes on the skin
change in or loss of taste
cracked, dry, or scaly skin
cracks in the skin
decreased weight
discoloration of the fingernails or toenails
dry mouth or skin
hair loss or thinning of the hair
lack or loss of strength
loosening of the fingernails
loss of heat from the body
muscle aches or spasms
rash with flat lesions or small raised lesions on the skin
redness or other discoloration of the skin
redness or soreness around the fingernails
stomach discomfort or upset
trouble sleeping
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Typically taken by mouth once a day with or without food
Can also be given through a feeding tube if you can’t swallow
Recommended treatment option for medullary thyroid cancer
Can cause a life-threatening irregular heart rhythm
Commonly causes diarrhea, high blood pressure, nausea, vomiting, and rash
Only available from providers and pharmacies enrolled in a special REMS program
Caprelsa (vandetanib) can be taken with or without food at the same time every day. It should be taken whole and not crushed or cut.
If you’re having trouble swallowing the Caprelsa (vandetanib) tablet whole or if you have a feeding tube, dissolve it in 2 oz of water and stir for 10 minutes, and then take it right away. Rinse any residue from your glass with 4 oz of water to get all of the medication.
If you miss a dose of Caprelsa (vandetanib), take the missed dose as soon as possible. If it’s within 12 hours of your next dose time, skip the missed dose and continue taking Caprelsa (vandetanib) at your usual time. Don’t take extra tablets to make up for a missed dose as this might cause additional side effects.
Caprelsa (vandetanib) can interact with many commonly used supplements, over-the-counter, and prescription medications including St. John's wort, digoxin, and medications that prolong the QT interval. It’s important to tell your provider and pharmacist about all the medications you’re taking to avoid serious interactions.
Caprelsa (vandetanib) can cause life-threatening heart rhythm changes. Due to the potential risk, you’ll need electrocardiograms (EKG) to monitor your heart rhythm. Tell your provider right away if your chest is pounding, or if you become short of breath, feel faint, or lightheaded.
Caprelsa (vandetanib) can also make you more sensitive to the sun. Be sure to wear sunscreen to prevent a sunburn while taking Caprelsa (vandetanib) while taking this medication.
If you’re able to become pregnant, use effective birth control during treatment and for 4 months after the last dose. And if you’re breastfeeding, avoid breastfeeding during treatment and for 4 months after the last dose. This is because Caprelsa (vandetanib) might cause harm to an unborn baby or breastfeeding infant.
Caprelsa (vandetanib) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Taking other medications that cause QT prolongation | Born with QT prolongation | History of abnormal heart rhythms (arrhythmias) | Taking medications that interact with Caprelsa (vandetanib)
Caprelsa (vandetanib) can lengthen the time period from when the heart squeezes and then relaxes. This is known as QT prolongation and is tested with an electrocardiogram (EKG). When this happens, it raises the risk for life-threatening abnormal heart rhythms.
Your risk of QT prolongation is greater if you have low levels of calcium, potassium, or magnesium in your body, or if you’re taking other medications that cause QT prolongation. Your provider might run tests to make sure your electrolytes are normal. Be sure to tell your provider about all the medications you’re taking and don’t start any new medications while taking Caprelsa (vandetanib) without talking to your provider or pharmacist first. If you feel your chest pounding, short of breath, chest pain, feeling faint, or lightheaded while taking Caprelsa (vandetanib), call 911 right away.
Due to the risk of QT prolongation, Caprelsa (vandetanib) is only available through a restricted program called Caprelsa (vandetanib) Risk Evaluation and Mitigation Strategy (REMS). This program is set so that only select providers and pharmacies can dispense or prescribe this medication. If you have questions about the REMS program, talk with your provider.
Caprelsa (vandetanib) can sometimes cause serious skin reactions, such as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). Although this is rare, these skin reactions can lead to hospitalization and other complications. Severe skin reactions can happen at any time while taking Caprelsa (vandetanib) and even up to 4 months after stopping treatment. Get medical care right away if you have a rash, blistering or peeling skin, painful sores on your face, swelling, or trouble breathing.
Rare, but serious lung problems, including inflammation of the lungs and pneumonia can happen while taking Caprelsa (vandetanib). Let your provider know if you have difficulty breathing, cough, or fatigue during your treatment.
Risk factors: Heart problems
Caprelsa (vandetanib) can lead to new or worsening heart failure and affect how well your heart pumps blood through your body. If you have heart problems, your provider will monitor you more regularly to make sure it doesn't get worse. Tell your provider if you have symptoms of heart problems including, shortness of breath that worsens with activity or while lying flat, swelling in your legs or feet, sudden weight gain, fatigue, or dizziness.
Rare cases of a brain condition called posterior reversible encephalopathy syndrome (PRES) have happened with people taking Caprelsa (vandetanib). It can occur from swelling and narrowing of blood vessels in the brain and have serious symptoms. Get medical help right away if you have sudden severe headaches, sudden confusion, sudden vision loss or vision changes, behavioral changes, or seizures. You’ll have to stop the medication right away if you have PRES.
Risk factors: Diabetes | High cholesterol | Alcohol use | High blood pressure
Caprelsa (vandetanib) can cause a stroke . Get emergency help right away if you have any signs of a stroke, including weakness or numbness in your arms, brain, legs, or face on one side of the body, trouble speaking, blurred vision, loss of balance, trouble walking, or confusion.
Caprelsa (vandetanib) can raise the risk of serious bleeding, which can result in death. Bleeding can happen anywhere in the body. Tell your provider right away if you experience any serious or unusual bleeding. Get urgent medical attention if you have severe or sudden headaches, extreme weakness, change in vision, large amounts of blood in your stool, or coughing up blood.
Caprelsa (vandetanib) can cause low levels of thyroid hormone (hypothyroidism), an important hormone needed for your body to function normally. Your provider will check your thyroid levels regularly while you’re taking this medication to make sure your thyroid hormone levels are normal.
Risk factors: History of high blood pressure
Caprelsa (vandetanib) can raise your blood pressure. Your provider might ask you to monitor your blood pressure at home. If your blood pressure starts to rise, you might need to start blood pressure lowering medications. Also if your blood pressure gets too high, your provider might have you lower your dose of Caprelsa (vandetanib) or stop taking the medication altogether. Let your provider know if you notice symptoms of high blood pressure, such as dizziness and headaches.
Risk factors: History of kidney problems
Caprelsa (vandetanib) can lead to kidney problems that can be serious. Your provider will monitor your kidney health regularly through lab work. If you develop kidney problems, you might need to stop Caprelsa (vandetanib). Talk with your provider if you notice changes in how often you urinate or if there is any blood in your urine so they can check for kidney issues.
Caprelsa (vandetanib) can make it harder for wounds to heal. Tell your provider if you have any injuries or if your wounds aren't healing or healing very slowly. Let your provider know if you have any planned surgeries or procedures. Your provider will need to give you instructions on when to stop and restart Caprelsa (vandetanib). In general, you should stop taking Caprelsa (vandetanib) for at least 1 month before surgery and for at least 2 weeks after surgery so that your wounds can heal.
Caprelsa (vandetanib) can cause harm to unborn babies. If you’re able to become pregnant, your provider will have you do a pregnancy test before starting treatment. Use effective birth control while taking this medication and for at least 4 months after your last dose.
The typical dose is 300 mg by mouth once a day, with or without food.
Your dose might be different if you have kidney problems or experience certain side effects.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Medullary thyroid cancer that can’t be treated with surgery or has spread to other areas of the body
Advanced or metastatic NSCLC with RET gene fusion in adults
Advanced or metastatic thyroid cancers with RET mutations in adults and children age 12 years and older
Advanced or metastatic tumors with RET mutations in adults, when other treatments haven’t worked or aren’t available
By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.
Al-Akchar, M., et al. (2022). Long QT syndrome. StatPearls.
Crotti, L., et al. (2008). Congenital long QT syndrome. Orphanet Journal of Rare Diseases.
Farzam, K., et al. (2023). QT prolonging drugs. StatPearls.
Genzyme Corporation. (2023). Caprelsa- vandetanib tablet, film coated [package insert]. DailyMed.
Labib, A., et al. (2023). Toxic epidermal necrolysis. StatPearls.
MedlinePlus. (2022). Thyroid cancer - medullary carcinoma.
MedlinePlus. (2022). Tube feeding.
National Cancer Institute. (2019). Medullary thyroid cancer (MTC).
National Comprehensive Cancer Network. (2022). Thyroid cancer.
National Heart, Lung, and Blood Institute. (2022). Long QT syndrome.
National Organization for Rare Disorders. (2018). Stevens-Johnson syndrome and toxic epidermal necrolysis.
Sudulagunta, S. R., et al. (2017). Posterior reversible encephalopathy syndrome (PRES). Oxford Medical Case Reports.
Thomson, R. J., et al. (2023). Tyrosine kinase inhibitors. StatPearls.
Triplett, J. D., et al. (2022). Posterior reversible encephalopathy syndrome (PRES): Diagnosis and management. Practical Neurology.
van Noord, C., et al. (2010). Drug- and non-drug-associated QT interval prolongation. British Journal of Clinical Pharmacology.
Wells, S. A., Jr., et al. (2012). Vandetanib in patients with locally advanced or metastatic medullary thyroid cancer: A randomized, double-blind phase III trial. Journal of Clinical Oncology.
Yap, Y. G., et al. (2003). Drug induced QT prolongation and torsades de pointes. Heart.
Research prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.