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What is a "Black Box Warning" for MS Drugs?

Be aware of potentially serious side effects of your medications


Updated February 15, 2011

The term "black box warning" sounds appropriately ominous. A black box warning is an alert that is printed on the package insert for prescription medication that describes potential serious side effects or adverse events linked to the drug. Black box warnings are also called "boxed warnings."

A black box warning appears separately from the usual list of side effects (usually surrounded by a black border) to indicate that the side effect that is described is very serious – even life-threatening – and that the link to the drug has been established. It is the strongest warning required by the US Food and Drug Administration (FDA).

The rationale behind black box warnings is that they will prompt physicians to carefully consider the risks of the medication before prescribing them and seriously evaluate if the use of the drug is warranted, or if there is another option.

Also, black box warnings should prompt discussion between the doctor and the patient as to the potential for these serious side effects, including how to recognize symptoms and what actions to take if they suspect this problem. Lastly, by being aware of the potential risk of the medication (through discussions with their docs and being able to read the black box warning themselves), patients themselves can make important decisions as to their level of comfort with the medication.

Black Box Warnings for MS Drugs

Only two drugs commonly used to treat multiple sclerosis (MS) have black box warnings, Tysabri and Novantrone. I am reprinting them in their entirety, so that you can read them for yourself and discuss them with your doctor. The numbers and headings that are referred to in the text of the warnings refer to the package inserts of the medications, which can be found here:

Bottom Line

Black box warnings are serious. They are not issued lightly, but only after there is sufficient evidence of the link of these risks to the medication in question.

Therefore, take the time to read any black box warning on your medication (you can easily find out if there is a black box warning by going to this handy little site - BlackBoxRx.com - and looking for the name of your medication. You can also go to the manufacturer's website and look for "Full Prescribing Information."

If your medication does carry a black box warning, make a list of your questions and concerns. Have an honest discussion with your doctor about the medication, including finding out if there are alternatives and what his or her rationale is for prescribing the drug. Make sure that you feel comfortable with the answers that you get before agreeing to start the medication.

Also, be sure that you understand the symptoms that may accompany the serious side effects mentioned in the black box warning, so that you can act quickly if you notice any of them.

I have included the full text of the black box warning for Tysabri below and Novantrone (on the next page):

Tysabri Black Box Warning


TYSABRI increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability. Cases of PML have been reported in patients taking TYSABRI who were recently or concomitantly treated with immunomodulators or immunosuppressants, as well as in patients receiving TYSABRI as monotherapy [see Warnings and Precautions (5.1)].

• Because of the risk of PML, TYSABRI is available only through a special restricted distribution program called the TOUCH® Prescribing Program. Under the TOUCH® Prescribing Program, only prescribers, infusion centers, and pharmacies associated with infusion centers registered with the program are able to prescribe, distribute, or infuse the product. In addition, TYSABRI must be administered only to patients who are enrolled in and meet all the conditions of the TOUCH® Prescribing Program [see Warnings and Precautions (5.1, 5.2)].

• Healthcare professionals should monitor patients on TYSABRI for any new sign or symptom that may be suggestive of PML. TYSABRI dosing should be withheld immediately at the first sign or symptom suggestive of PML. For diagnosis, an evaluation that includes a gadolinium- enhanced magnetic resonance imaging (MRI) scan of the brain and, when indicated, cerebrospinal fluid analysis for JC viral DNA are recommended [see Contraindications (4), Warnings and Precautions (5.1)].

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