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Natalizumab (By injection)

Natalizumab (na-ta-LYE-zoo-mab)

Treats Crohn disease and multiple sclerosis (MS).

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive it if you had an allergic reaction to natalizumab, or if you have had progressive multifocal leukoencephalopathy (PML).

How to Use This Medicine:


  • Your doctor will prescribe your dose and schedule. This medicine is given through a needle placed in a vein.
  • A nurse or other health provider will give you this medicine.
  • This medicine must be injected slowly, so the needle will have to remain in place for about an hour.
  • You will need to stay at the clinic or office for 1 hour after you receive this medicine, to make sure you do not have any serious side effects.
  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
  • Missed dose:This medicine needs to be given on a fixed schedule. If you miss a dose, call your doctor, home health caregiver, or treatment clinic for instructions.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Some medicines can affect how natalizumab works. Tell your doctor if you are using medicine that weakens your immune system, including azathioprine, cyclophosphamide, cyclosporine, mercaptopurine, methotrexate, mitoxantrone, mycophenolate mofetil, or steroid medicine.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have liver disease, a fever, or any kind of infection. Tell your doctor if you have a weak immune system (that may be caused by HIV/AIDS, cancer, or an organ transplant).
  • This medicine may cause the following problems:
    • Increased risk for infections
    • Infections of the brain or nervous system, including PML, encephalitis, retinal necrosis, or meningitis
    • Liver problems
  • Make sure any doctor or dentist who treats you knows that you are using this medicine.
  • You may need to have an MRI scan before you start receiving this medicine.
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
  • Fever, chills, runny or stuffy nose, cough, sore throat, body aches
  • Warmth or redness in your face, neck, arms, or upper chest, dizziness
  • Weakness on one side of your body, clumsiness, trouble seeing or vision changes, confusion, memory problems, unusual behavior

If you notice these less serious side effects, talk with your doctor:

  • Joint or muscle pain
  • Diarrhea, stomach upset
  • Headache
  • Tiredness
  • Pain, itching, burning, swelling, bleeding, or a lump under your skin where the needle is placed

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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