Natalizumab is a prescription medication primarily used to manage multiple sclerosis (MS) symptoms. It’s also sometimes prescribed for Crohn’s disease. Sold under the brand name Tysabri, it doesn’t cure either disease, but helps improve quality of life.

Natalizumab comes in an intravenous (IV) solution. Unlike other prescription medications, these infusions are only provided in a medical setting. You won’t be given natalizumab to take at home. Instead, a nurse will provide the medication through a needle.

The TOUCH Program

All doctors who prescribe natalizumab are required to enroll their patients in the TOUCH program. You can’t take natalizumab unless you enroll in the program. This ensures that you get all of the safety information you need.

TOUCH, which stands for Tysabri Outreach: Unified Commitment to Health, is a medication regulation program. The program ensures that only subscribed patients and providers can participate in treatment. It also makes sure that only certain sites can dispense the medication.

Participating doctors are obligated to see you every three months after you start treatment. Once your doctor observes satisfactory progress, they may reduce your visits to once every six months.

You should discuss all possible effects and dangers with your doctor before you start natalizumab. You may be monitored in a medical facility for a short time after each dose, but many side effects can occur after you go home.

Common and Serious Side Effects

Like any drug, natalizumab carries the risk of side effects. It’s important to know what these effects are so that you can look out for adverse reactions. The most common side effects are:

  • headaches
  • excessive fatigue
  • itchy skin
  • painful joints
  • increased heart rate
  • muscle pain
  • irregular periods in women

Side effects can come and go. If any side effect interferes with your quality of life, see your doctor for a possible solution.

Though some natalizumab side effects aren’t life threatening, others are more severe. Be on the lookout for serious side effects and report the following right away:

  • abdominal pain
  • depression
  • blurred vision
  • bladder pain and urine changes
  • flushing skin
  • nausea or vomiting

Natalizumab can also worsen preexisting diseases of the liver. Jaundice, yellowing of the eyes and skin, are common signs of liver problems.

Allergic Reactions 

Allergies vary from person to person. There is no way of knowing if you’ll have an allergic reaction to natalizumab, unless you’ve had an allergic reaction to the medication in the past. Tell your doctor if you have a history of allergic reactions to other medications.

Seek emergency medical help if you experience the following after natalizumab treatment:

  • rash or hives (may also itch)
  • breathing difficulties
  • wheezing
  • chest pain
  • fever or chills
  • dizziness

These symptoms also may be experienced during anaphylaxis, a severe and life-threatening allergic reaction.

Decreased Immunity and PML Infection

One serious concern with this medication is the possibility of decreased immunity. This means that your immune system may not fight off infections like the common cold and flu viruses, or even more serious infections, as effectively.

Natalizumab might not be appropriate if you already have a weak immune system related to:

  • an organ transplant
  • HIV or AIDS
  • lymphoma
  • leukemia

Natalizumab puts you at higher risk for respiratory and urinary tract infections. It also puts you at risk for getting a brain infection called progressive multifocal leukoencephalopathy (PML). Though it’s rare, there’s no way to prevent PML, and it has no cure. PML can cause serious muscle disability and even death. It can occur in anyone with decreased immunity.

According to Tysabri, the chance of developing PML is greater if you use the medicine for two years or longer. Talk to your doctor about your risk if you plan on using the drug long term.

Risk Groups

Natalizumab is an FDA Pregnancy Category C drug. This means that no studies have been conducted on the effects of the medication in pregnant women, though animal studies may have shown adverse effects.

Babies have the potential of being born with birth defects. There are also concerns for nursing babies, as the drug may pass through milk and cause life-threatening effects. To protect your baby, consider using formula or a different type of medication while nursing.

Children and the elderly are both high-risk groups when it comes to catching and battling serious illnesses. While doctors might prescribe natalizumab for some patients in these age groups, it’s important to know that there is no safety guarantee. As of 2013, no studies had been conducted on the effects of this medication within either age group. In addition, the medicine’s benefits for children is questionable.

Benefits vs. Risks

Natalizumab can be very effective in keeping MS symptoms and Crohn’s disease at bay. But not all MS and Crohn’s patients react favorably to the medication. The potential risks are severe enough to warrant regular monitoring of your condition. Treatment also requires the commitment to see your doctor regularly and to report your side effects.