Although the FDA has approved of Xolair for treating allergic asthma, one potential adverse effect of this medication is anaphylaxis, which may include allergy symptoms such as trouble in breathing, chest tightness, dizziness, Fainting, itching and hives, and swelling of the mouth and throat. The FDA is now requesting Genentech, the manufacturer, to add a boxed warning to the product label.

Due to the nature of continued reports in the post-marketing experience, including their life-threatening potential, frequency, and the possibility for the delayed onset of anaphylaxis, FDA has now requested that Genentech, Inc., add the boxed warning and strengthen the existing warning.

The strengthened warning includes the possibility of a patient developing anaphylaxis after any dose of Xolair, even if there was no reaction to the first dose. Also, anaphylaxis after administration of Xolair may be delayed up to 24 hours after the dose is given. Health care providers should be prepared to manage life-threatening anaphylaxis following Xolair administration and observe patients for at least two hours after an injection. Following administration of Xolair, patients should also carry and know how to initiate emergency self-treatment for anaphylaxis.

I guess some of you might wonder why it was approved in the first place, if it's so dangerous. Apparently, during clinical trials, Xolair has been demonstrated to be effective for people with moderate to severe persistent asthma who have tested positive for a perennial aeroallergen (pollen, grass or dust). The cases of anaphylaxis during the trials were low enough (1 in 1000 patients) and the expected improvement in the quality life among those who did not suffer anaphylaxis were considerable enough to approve its release to the market.

As with any other drug, there are always side effects and contra-indications. So I suppose, there's always a risk involved. It's just a matter of being aware of the potential risks, and being prepared for it.