Important safety information related to taking CRYSVITA® (burosumab-twza)

Learn about the potential side effects related to taking CRYSVITA

You should not take CRYSVITA if:

  • You take an oral phosphate supplement and/or a specific form of vitamin D supplement (such as calcitriol, paricalcitol, doxercalciferol, calcifediol)
  • Your phosphorus levels from a blood sample are within or above the normal range for age
  • You have kidney problems

What is the most important information I should know about CRYSVITA?

  • Some patients developed allergic reactions (such as a rash or hives) while taking CRYSVITA. Your doctor will monitor you for symptoms of an allergic reaction while you are taking CRYSVITA.
  • A high level of phosphorus in the blood has been reported in some patients receiving CRYSVITA. This may be related to a risk of high calcium levels in the kidneys. Your doctor will collect samples to monitor your levels.
  • Administration of CRYSVITA may result in reactions at the injection site, such as hives, reddening of the skin, rash, swelling, bruising, pain, severe itching of the skin, and a collection of blood outside of a blood vessel (hematoma).

What are the possible
side effects of CRYSVITA
in children?

The following side effects were observed in 10% or more of children who were treated with CRYSVITA across all studies.

The most common side effects reported in children with X-LINKED HYPOPHOSPHATEMIA (XLH) who were treated with CRYSVITA were:

  • Fever
  • Injection site reaction
  • Cough
  • Vomiting
  • Pain in arms and legs
  • Headache
  • Tooth infections
  • Dental cavities
  • Diarrhea
  • Decreased vitamin D levels
  • Toothache
  • Constipation
  • Muscle pain
  • Rash
  • Dizziness
  • Nausea

Muscle pain and dizziness were also observed in more than 10% of children receiving CRYSVITA in Studies 2 and 3.

While taking CRYSVITA, tell your doctor if your child experiences:

  • An allergic reaction such as rash or hives
  • A rash, swelling, bruising, or other reaction at the injection site

These are not all the possible side effects of CRYSVITA. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Ultragenyx at 1-888-756-8657.

Please see full Prescribing Information for additional Important Safety Information.

What are the possible side effects of CRYSVITA in adults?

The following side effects were observed in more than 5% of adults who were treated with CRYSVITA every 4 weeks and in at least 2 patients more than with placebo in the first 24 weeks of Study 4.

The most common side effects reported in adults with XLH who were treated with CRYSVITA were:

  • Back pain
  • Headache
  • Tooth infection
  • Restless legs syndrome
  • Decreased vitamin D levels
  • Dizziness
  • Constipation
  • Muscle spasms
  • Phosphorus levels increased in the blood

Narrowing of the spaces within the spine is common in adults with XLH, and pressure on the spinal cord has been reported in adults taking CRYSVITA. It is not known if taking CRYSVITA worsens the narrowing of the spaces within the spine or the pressure on the spinal cord.

Before taking CRYSVITA, tell your doctor about all of your medications (including supplements) and medical conditions, including if you:

  • Are taking oral phosphate and/or active vitamin D (such as calcitriol, paricalcitol, doxercalciferol, calcifediol)
  • Are pregnant, think you may be pregnant, or plan to become pregnant. There is not enough experience to know if CRYSVITA may harm your unborn baby. Report pregnancies to the Ultragenyx Adverse Event reporting line at 1-888-756-8657.
  • Are breastfeeding or plan to breastfeed. There is not enough experience to know if CRYSVITA passes into your breast milk. Talk with your doctor about the best way to feed your baby while you receive CRYSVITA.

While taking CRYSVITA, tell your doctor if you experience:

  • An allergic reaction such as rash or hives
  • A rash, swelling, bruising, or other reaction at the injection site
  • New or worsening restless legs syndrome

These are not all the possible side effects of CRYSVITA. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at (800) FDA-1088 or www.fda.gov/medwatch. You may also report side effects to Ultragenyx at 1-888-756-8657.

Please see full Prescribing Information for additional Important Safety Information.