Adult Medication

Brand Names: US


Brand Names: Canada



  • A very bad brain problem called progressive multifocal leukoencephalopathy (PML) may happen with this drug. It may cause disability or death. Tell your doctor right away if you have signs like confusion, memory problems, low mood (depression), change in the way you act, change in strength on 1 side is greater than the other, trouble speaking or thinking, change in balance, or change in eyesight.
  • Watch for side effects while getting this drug and for 6 months after your last dose.
  • You may only get this drug through a special program. Talk with your doctor.

What is this drug used for?

  • It is used to treat MS (multiple sclerosis).
  • It is used to treat Crohn’s disease.

What do I need to tell my doctor BEFORE I take this drug?

  • If you have an allergy to natalizumab or any other part of this drug.
  • If you are allergic to mouse proteins, talk with the doctor.
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you have had a brain infection called progressive multifocal leukoencephalopathy.
  • If you are taking any of these drugs: 6-mercaptopurine, adalimumab, azathioprine, certolizumab, cyclosporine, etanercept, golimumab, infliximab, or methotrexate.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • Some people have had side effects within a few hours of the start of the infusion. Tell your doctor if you have any bad effects during this time.
  • You may have more chance of getting an infection. Wash hands often. Stay away from people with infections, colds, or flu.
  • Talk with your doctor before getting any vaccines. Use with this drug may either raise the chance of an infection or make the vaccine not work as well.
  • This drug is not approved for use in children. Talk with the doctor.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of infection like fever, chills, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or wound that will not heal.
  • Signs of a urinary tract infection (UTI) like blood in the urine, burning or pain when passing urine, feeling the need to pass urine often or right away, fever, lower stomach pain, or pelvic pain.
  • Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • If you are planning to harm yourself or the want to harm yourself gets worse.
  • Low mood (depression).
  • Very upset stomach or throwing up.
  • Dizziness.
  • Flushing.
  • Shortness of breath.
  • Chest pain or pressure or passing out.
  • Vaginal itching or discharge.
  • Very bad and sometimes deadly infections of the brain or spinal cord caused by herpes viruses have happened with this drug. Call your doctor right away if you have sudden fever, very bad headache, or a change in thinking clearly and with logic.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
  • Headache.
  • Upset stomach.
  • Loose stools (diarrhea).
  • Belly pain.
  • Feeling tired or weak.
  • Joint pain.
  • Back pain.
  • Pain in arms or legs.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.
  • It is given as an infusion into a vein over a period of time.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

How do I store and/or throw out this drug?

  • If you need to store this drug at home, talk with your doctor, nurse, or pharmacist about how to store it.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Check with your pharmacist about how to throw out unused drugs.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

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