Clarks Nutrition and Natural Foods Markets

Search Healthnotes

Natalizumab

Medical Alert

Your condition can cause complications in a medical emergency. For information about enrolling in MedicAlert, call 1-888-633-4298 (US) or 1-800-668-1507 (Canada).

Warning

Natalizumab increases your risk of getting a rare but very serious (sometimes fatal) brain infection (progressive multifocal leukoencephalopathy-PML). This risk may be higher the longer you use natalizumab and if you recently used or are currently using other medications that weaken the immune system/increase your risk of infection (such as immunosuppressants, cancer chemotherapy) or other medications that affect the immune system (immunomodulators). Ask your doctor or pharmacist for more information. See also Side Effects and Drug Interactions sections. The risk of PML may also be higher if you have been infected with the virus that causes this infection (JC virus). Your doctor may order a test to see if you have been infected with this virus. Because this medication increases the risk of PML, it is usually used alone and only when other treatments have not worked or you are unable to use them.

To receive natalizumab in the United States, you must understand, agree to, and carefully follow the requirements of the REMS Program for this medication. If you live in Canada or any other country, consult your doctor and pharmacist for your country's regulations.

Precautions

Before using this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: a certain virus infection (progressive multifocal leukoencephalopathy-PML), history of certain virus infections that keep coming back (such as herpes, shingles), weakened immune system (such as leukemia, lymphoma, HIV infection, organ transplant), current infections, mental/mood disorders (such as depression).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during pregnancy may have low platelet and red blood cell counts. Tell the doctor right away if your baby develops easy bruising/bleeding. Discuss the risks and benefits with your doctor.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.

Side Effects

See also How to Use section.

Headache, joint pain, redness/irritation at the injection site, swelling hands/feet/ankles, or changes in menstrual cycle may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: headache that is severe or doesn't go away, stiff/painful neck, fast/pounding heartbeat, easy bruising/bleeding, signs of infection (such as sore throat that doesn't go away, fever, breathing problems, unusual vaginal discharge, painful/frequent urination), mood changes (such as depression, suicidal thoughts), severe stomach/abdominal pain.

This drug increases the risk of a rare, possibly fatal, brain infection (see Warning section for more details). This condition may occur during treatment or, in some cases, after treatment has stopped. In MS patients, the symptoms of PML can seem like an attack of worsening MS. Whether you are using this drug or have stopped using it within the last 6 months, tell your doctor right away of any new or worsening symptoms that have lasted for several days such as: clumsiness, sudden change in your thinking (such as confusion, difficulty concentrating), difficulty moving muscles, seizure, problems with speech, vision changes.

This drug may rarely cause serious liver problems. If you notice any of the following rare but very serious side effects, tell your doctor right away: nausea/vomiting that doesn't stop, dark urine, yellowing eyes/skin, feeling tired/weak.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.

Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

Learn more about First DataBank

There are some limitations on the information provided in “Nutrient Interactions.” Do NOT rely solely on the information in this article. Please read the disclaimer.

Learn more about TraceGains, the company.

TraceGains and/or its suppliers make no warranties or representations as to the accuracy or completeness of this content herein or that of any organization referred or linked to within this content and will not be liable for any damages arising out of your access to or use of any information found herein or that of any organization referred to within this content.

Information expires December 2025.