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Biologics are a class of drugs used to treat Crohn’s disease, a type of inflammatory bowel disease (IBD). Common symptoms of Crohn’s disease may include:

  • Stomach pain
  • Cramping
  • Diarrhea
  • Rectal bleeding

Crohn’s disease is a type of autoimmune disorder. Your immune system typically protects the body from foreign invaders such as bacteria and viruses. To do this, it needs to be able to tell what is helpful and what is harmful.

If you have an autoimmune disease, your body’s immune system can’t tell the difference between the good and bad and attacks healthy tissue in your body. In the case of Crohn’s disease, the immune system attacks tissue in the digestive tract, causing inflammation and damage.

Although Crohn’s disease can’t be cured, it usually can be controlled with medication. The goals of treatment are:

  • Relieve symptoms
  • Prevent flare-ups
  • Improve quality of life  

For people with moderate to severe Crohn’s disease, biologics can play an important role in treatment.

How Biologics Are Different From Other Treatments

Biologics are created from living organisms. They target specific proteins in your body that cause inflammation.

Other drugs used to treat Crohn’s, such as corticosteroids, suppress your entire immune system and can cause significant side effects. Biologics may have fewer side effects. But some of the side effects from these drugs also can be very serious.

Four biologics have been approved by the FDA for the treatment of Crohn’s disease:

  • Cimzia (certolizumab pegol)
  • Humira (adalimumab) 
  • Remicade (infliximab)
  • Tysabri (natalizumab)

Cimzia, Humira, and Remicade target a protein called TNF-alpha that's involved in inflammation. Tysabri works by blocking specific cells in the bloodstream that lead to inflammation.


Cimzia reduces symptoms of moderate to severe Crohn’s disease in people who have not responded to standard treatment. It also helps keeps Crohn’s symptoms from returning.

How given: injection under the skin

Common side effects:

  • Rash
  • Swelling
  • Joint pain
  • Upper respiratory tract infection
  • Urinary tract infection

Other potential side effects: All the drugs in this class share the potential for some more serious side effects, including developing infections like tuberculosis (TB) and sepsis. These drugs don't cause TB but may trigger the infection in people who have already been exposed to the disease. 

You may be vulnerable to other infections, as well. Tell your doctor right away if you have an infection, or develop a cough, fever, fatigue, or the flu. In rare cases, some people have developed certain cancers such as lymphoma.