What is omalizumab, and how does it work (mechanism of action)?

Omalizumab is an injectable drug that is
used for treating asthma. Omalizumab is a protein that resembles one type of
human antibody. Antibodies are proteins produced by the body that recognize
foreign substances such as bacteria (that cause infection) and pollens (that
cause allergies). Once they recognize a foreign substance, the antibodies attach
to receptors on two types of cells in tissues and blood, mast cells and
basophils. These cells then release chemicals that cause an allergic reaction
that leads to inflammation. Omalizumab blocks the receptors on the surfaces of
the mast cells and basophils to which antibodies attach, thereby preventing
antibodies from attaching to the cells. As a result, the cells do not release
their chemicals, and the allergic reaction and inflammation are prevented. In
asthmatic individuals, allergic reactions often cause attacks of asthma.
Omalizumab reduces the attacks of asthma by preventing the allergic reactions
caused by foreign substances. Omalizumab was approved by the FDA in June 2003.

What brand names are available for omalizumab?


Is omalizumab available as a generic drug?

GENERIC AVAILABLE: No PREPARATIONS: Sterile powder for Injection: 5 ml
vial (150 mg)

Do I need a prescription for omalizumab?


What are the side effects of omalizumab?

The most common side effects observed in patients treated with omalizumab are: 

  • headaches,
  • viral infections,
  • upper respiratory tract infections,
  • injection-site reactions such as

Use of omalizumab may also lead to serious, life-threatening allergic reactions (anaphylaxis) which manifest as bronchospasm with difficulty breathing, fainting, low blood pressure, and swelling of the tongue or throat.

It is recommended that patients be observed for these reactions for at least two hours after injection of omalizumab; however, these reactions can occur up to 24 hours or longer after the injections, and they have occurred even after one year of regular treatment. Since allergic reactions can occur after any dose, patients should carry medications for emergency self-treatment. In clinical trials cancer occurred more frequently in patients who took omalizumab.

Medically Reviewed by a Doctor on 5/15/2017

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.