Natalizumab Injection


Natalizumab is used to prevent episodes of symptoms and slow the worsening of disability in adults who have relapsing forms of multiple sclerosis (MS; a disease in which the nerves do not function properly and people may experience weakness, numbness, loss of muscle coordination, and problems with vision, speech, and bladder control), including:

  • clinically isolated syndrome (CIS; first nerve symptom episode that lasts at least 24 hours),
  • relapsing-remitting disease (course of disease where symptoms flare up from time to time),
  • active secondary progressive disease (later stage of disease with continuous worsening of symptoms.)

Natalizumab is also used to treat and prevent episodes of symptoms in adults who have Crohn’s disease (a condition in which the body attacks the lining of the digestive tract, causing pain, diarrhea, weight loss, and fever) who have not been helped by other medications or who cannot take other medications. Natalizumab is in a class of medications called monoclonal antibodies. It works by stopping certain cells of the immune system from reaching the brain and spinal cord or digestive tract and causing damage.

Side Effects Of Natalizumab Injection

Natalizumab may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • headache
  • extreme tiredness
  • drowsiness
  • joint pain or swelling
  • pain in arms or legs
  • back pain
  • swelling of the arms, hands, feet, ankles, or lower legs
  • muscle cramps
  • stomach pain
  • diarrhea
  • heartburn
  • constipation
  • gas
  • weight gain or loss
  • depression
  • night sweats
  • painful, irregular, or missed menstruation (period)
  • swelling, redness, burning, or itching of the vagina
  • white vaginal discharge
  • difficulty controlling urination
  • tooth pain
  • mouth sores
  • rash
  • dry skin
  • itching

Some side effects can be serious. If you experience any of the following symptoms or those mentioned in the WARNINGS and PRECAUTIONS section, call your doctor immediately or get emergency medical treatment:

  • sore throat, fever, cough, chills, flu-like symptoms, stomach cramps, diarrhea, frequent or painful urination, sudden need to urinate right away, or other signs of infection
  • yellowing of the skin or eyes, nausea, vomiting, extreme tiredness, loss of appetite, dark urine, right upper abdominal pain
  • vision changes, eye redness, or pain
  • unusual bleeding or bruising
  • small, round, red, or purple-colored spots on the skin
  • heavy menstrual bleeding

Natalizumab injection may cause other side effects. Call your doctor if you have any unusual problems while receiving this medication.

Warnings & Precautions

Before receiving natalizumab injection:

  • tell your doctor and pharmacist if you are allergic to natalizumab, any other medications, or any of the ingredients in natalizumab injection. Ask your doctor or pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking. Be sure to mention the medications listed in the WARNINGS and PRECAUTIONS section. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have ever received natalizumab injection before and if you have or have ever had any of the conditions listed in the WARNINGS and PRECAUTIONS section. Before you receive each infusion of natalizumab, tell your doctor if you have a fever or any type of infection, including infections that last for a long time such as shingles (a rash that may occur from time to time in people who have had chickenpox in the past).
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while receiving natalizumab injection, call your doctor.
  • do not have any vaccinations without talking to your doctor.

Natalizumab Injection Dosage

Natalizumab comes as a concentrated solution (liquid) to be diluted and injected slowly into a vein by a doctor or nurse. It is usually given once every 4 weeks in a registered infusion center. It will take about 1 hour for you to receive your entire dose of natalizumab.

Natalizumab may cause serious allergic reactions that are most likely to happen within 2 hours after the beginning of an infusion but may happen at any time during your treatment. You will have to stay at the infusion center for 1 hour after your infusion is finished. A doctor or nurse will monitor you during this time to see if you are having a serious reaction to the medication. Tell your doctor or nurse if you experience any unusual symptoms such as hives, rash, itching, difficulty swallowing or breathing, fever, dizziness, headache, chest pain, flushing, nausea, or chills, especially if they occur within 2 hours after the start of your infusion.

If you are receiving natalizumab injection to treat Crohn’s disease, your symptoms should improve during the first few months of your treatment. Tell your doctor if your symptoms have not improved after 12 weeks of treatment. Your doctor may stop treating you with natalizumab injection.

Natalizumab may help control your symptoms but will not cure your condition. Keep all appointments to receive natalizumab injection even if you feel well.


Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body’s response to natalizumab injection.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.