Von Willebrand factor is a naturally occurring protein in the blood that helps blood to clot. People with an inherited blood-clotting disorder called von Willebrand disease do not have enough of this protein in their blood. A lack of von Willebrand factor can cause uncontrolled bleeding.

Von Willebrand factor is used to control bleeding episodes in adults with von Willebrand disease.

Von Willebrand factor may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Von Willebrand factor is injected into a vein through an IV. You may be shown how to use an IV at home. Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of needles, IV tubing, and other items used.

Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.

Von Willebrand factor is a powder medicine that must be mixed with a liquid (diluent) before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medicine. Mixed medicine must be used within 3 hours if you keep it at room temperature.

Do not shake the mixed medicine. Prepare your dose only when you are ready to give an injection.

Do not use the medicine if it looks cloudy or has particles in it. Call your pharmacist for new medicine.

Tell your doctor if you have any changes in weight. Von Willebrand factor doses are based on weight, and any changes may affect the dose.

You may need frequent medical tests to help your doctor determine how long to treat you with von Willebrand factor.

Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.

Store this medicine in its original carton in a refrigerator until you are ready to prepare your dose. Do not allow the to medicine freeze.

You may also store the carton at room temperature for up to 12 months.

Do not use this medicine if the expiration date on the label has passed.

You should not use von Willebrand factor if you have ever had a severe allergic reaction to von Willebrand factor, or if you are allergic to mice or hamsters.

To make sure von Willebrand factor is safe for you, tell your doctor if you have ever been told that you have:

• inhibitors to von Willebrand factor; or

• inhibitors to blood coagulation factor VIII.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether von Willebrand factor passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

Since von Willebrand factor is used when needed, it does not have a daily dosing schedule. Call your doctor promptly if your symptoms do not improve after using von Willebrand factor.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives, itching; tightness in your throat or chest, difficult breathing; swelling of your face, lips, tongue, or throat.

Von Willebrand factor may cause serious side effects. Call your doctor at once if you have:

• sudden numbness or weakness (especially on one side of the body);

• chest pain or pressure, sudden cough, wheezing, rapid breathing, coughing up blood;

• pain, swelling, warmth, or redness in one or both legs;

• nausea; or

• a light-headed feeling, like you might pass out.

Common side effects of von Willebrand factor may include:

• a burning sensation around the IV needle;

• dizziness, nausea;

• muscle twitching;

• unusual or unpleasant taste in the mouth;

• hot flashes;

• fast heart rate;

• itching;

• chest discomfort; or

• increased blood pressure.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may interact with von Willebrand factor, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.