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CRYSVITA® (burosumab-twza) injection 10, 20, 30 mg/mL

CRYSVITA treats

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A bone fracture

What is XLH?

XLH is lifelong and progressive.

X-linked hypophosphatemia (XLH) is a genetic condition (something you are born with) that can change over time. It can impact both children and adults.

Symptoms of XLH can start early in life, and new symptoms may appear in adulthood. Early diagnosis and treatment of XLH may help manage symptoms.

What causes XLH?

People with XLH have lower than normal levels of phosphorus in their blood. Phosphorus is a mineral that is important to the
health of bones and muscles.

The low levels of phosphorus are caused by a change (variant) in a specific gene called the PHEX gene. This gene mutation causes the body to produce too much of
a hormone called fibroblast growth factor 23 (FGF23).

PHEX=phosphate regulating endopeptidase X-linked.

Phosphate element, as shown in the periodic table

XLH causes the body to lose phosphorus in the form of phosphate by this process:

An abstract shape in a stylized protein shape labeled FGF23, which is a hormone in the bone

The body produces too much FGF23

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The kidneys removing too much phosphate from the body due to excess FGF23

Extra FGF23 causes the body to
lose too much phosphate through
the urine instead of keeping it in the
bloodstream

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A bone becoming soft and weak due to low phosphate levels

Low phosphorus levels can
lead to weakened bones

This process is known as phosphate wasting. In XLH, phosphate wasting is ongoing and causes the level of phosphorus in the blood to drop too low. Low levels of phosphorus in the blood are known as hypophosphatemia (the H in XLH).

XLH can continue to affect a person’s bones and muscles as they age.

XLH can be inherited from parents

The X and L in XLH stand for X-linked, meaning the condition is passed down through the X chromosome. Chromosomes are structures inside the body’s cells that contain your genes. Everyone has at least one X chromosome. Men have an X and a Y chromosome (XY) and women have two X chromosomes (XX).

x-gene

Chromosome with XLH

If a father has XLH and
the mother does not:

Diagram showing X-linked inheritance when a father has XLH and the mother does not. All daughters inherit the affected X chromosome and have XLH (100% chance), while no sons inherit XLH (0% chance)

All daughters will have XLH.
No sons will have XLH.

This is because daughters inherit an X
chromosome from their father. No sons will
have XLH because sons get the
X chromosome from their mother.

If a mother has XLH and
the father does not:

Diagram showing X-linked inheritance when a mother has XLH and the father does not. Both sons and daughters have a 50% chance of inheriting XLH

Both sons and daughters have a
50% chance of having XLH.

This is because all children inherit an X chromosome from their mother.

People can inherit XLH from either their father or mother. If 1 member of the family has XLH, there is a good chance that other members may have it, too.

Robert, a person living with XLH, smiling

Real XLH stories

Uncovering the truth about XLH

“One thing we did know is that XLH ran in my family. My grandmother had XLH; my mom and sister have XLH, too.”

Read Robert’s full story

XLH can also happen spontaneously

XLH can also occur in those without any family history. This is known as a
spontaneous case of XLH or spontaneous XLH.

Up to 3 in 10 people with XLH develop it due to spontaneous gene variants, which can then be
passed on to their future children.

A DNA strand

This information doesn’t replace talking with your doctor.
Be sure to ask them about CRYSVITA and whether it’s right for you.

Find out how CRYSVITA works to restore the balance of phosphate in the body

How CRYSVITA works
Antibodies binding to FGF23 proteins to help reduce phosphate loss and increase phosphorus levels in the body for people with XLH
Indication
What is CRYSVITA?

CRYSVITA is a prescription medicine used to treat adults and children 6 months of age and older with X-linked hypophosphatemia (XLH).

read more
What is CRYSVITA?

CRYSVITA is a prescription medicine used to treat adults and children 6 months of age and older with X-linked hypophosphatemia (XLH).

Important Safety Information

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 you should know about CRYSVITA?

  • Some patients developed allergic reactions (e.g., rash and hives) while taking CRYSVITA. Your doctor will monitor you for symptoms of an allergic reaction while you are taking CRYSVITA. Your treatment may need to be discontinued for serious allergic reactions.
  • High levels of phosphorus in the blood have been reported in some patients taking CRYSVITA. This may be related to a risk of high calcium levels in the kidneys. Your doctor will collect blood samples to monitor your levels. If you are already taking CRYSVITA, dose interruption and/or dose reduction may be required based on your serum phosphorus levels.
  • High levels of calcium in the blood have been reported in patients taking CRYSVITA. The risk is greater in patients with pre-existing hyperparathyroidism (overactive parathyroid glands), for those who are unable to move for extended periods of time, become dehydrated, have high vitamin D levels, or have kidney issues. If you are at greater risk, your doctor will monitor your blood calcium and parathyroid hormone levels before you start and while taking CRYSVITA. If you develop high levels of blood calcium, your doctor may need to stop your treatment until it is adequately managed.
  • 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 collection of blood outside of a blood vessel (i.e., hematoma). Call your doctor if you develop an injection site reaction. CRYSVITA may be discontinued if severe injection site reactions occur.

What are the possible side effects of CRYSVITA?

  • Adverse reactions that were seen in children with XLH are:
  • Fever
  • Injection site reaction
  • Cough
  • Vomiting
  • Pain in arms and legs
  • Headache
  • Tooth abscess
  • Dental cavities
  • Diarrhea
  • Decreased vitamin D levels
  • Toothache
  • Constipation
  • Muscle pain
  • Rash
  • Dizziness
  • Nausea
  • Adverse reactions that were seen in adults with XLH are:
  • 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 Kyowa Kirin, Inc. Adverse Event reporting line at 1-844-768-3544.
  • 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 Kyowa Kirin, Inc. at 1-844-768-3544.

For important risk and use information, please see the full Prescribing Information for CRYSVITA.

What is CRYSVITA?

CRYSVITA is a prescription medicine used to treat adults and children 6 months of age and older with X-linked hypophosphatemia (XLH).

Important Safety Information

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 you should know about CRYSVITA?

  • Some patients developed allergic reactions (e.g., rash and hives) while taking CRYSVITA. Your doctor will monitor you for symptoms of an allergic reaction while you are taking CRYSVITA. Your treatment may need to be discontinued for serious allergic reactions.
  • High levels of phosphorus in the blood have been reported in some patients taking CRYSVITA. This may be related to a risk of high calcium levels in the kidneys. Your doctor will collect blood samples to monitor your levels. If you are already taking CRYSVITA, dose interruption and/or dose reduction may be required based on your serum phosphorus levels.
  • High levels of calcium in the blood have been reported in patients taking CRYSVITA. The risk is greater in patients with pre-existing hyperparathyroidism (overactive parathyroid glands), for those who are unable to move for extended periods of time, become dehydrated, have high vitamin D levels, or have kidney issues. If you are at greater risk, your doctor will monitor your blood calcium and parathyroid hormone levels before you start and while taking CRYSVITA. If you develop high levels of blood calcium, your doctor may need to stop your treatment until it is adequately managed.
  • 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 collection of blood outside of a blood vessel (i.e., hematoma). Call your doctor if you develop an injection site reaction. CRYSVITA may be discontinued if severe injection site reactions occur.

What are the possible side effects of CRYSVITA?

  • Adverse reactions that were seen in children with XLH are:
  • Fever
  • Injection site reaction
  • Cough
  • Vomiting
  • Pain in arms and legs
  • Headache
  • Tooth abscess
  • Dental cavities
  • Diarrhea
  • Decreased vitamin D levels
  • Toothache
  • Constipation
  • Muscle pain
  • Rash
  • Dizziness
  • Nausea
  • Adverse reactions that were seen in adults with XLH are:
  • 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 Kyowa Kirin, Inc. Adverse Event reporting line at 1-844-768-3544.
  • 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 Kyowa Kirin, Inc. at 1-844-768-3544.

For important risk and use information, please see the full Prescribing Information for CRYSVITA.

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COMM-US-CRY-0925 June 2026