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What Are Immunomodulators?

One type of drug that targets your immune system is called an immunomodulator. These drugs work by curbing the immune system throughout the body, not just the gut.

Some common types of immunomodulators are:

  • Azathioprine
  • Methotrexate
  • Mercaptopurine

Azathioprine and mercaptopurine may be used to keep flare-ups away. But either can take months to start working. You may also need a faster-acting drug such as a corticosteroid.

Side effects of azathioprine and mercaptopurine include nausea, vomiting, and less resistance to infection.

Side effects of methotrexate include:

  • Nausea and diarrhea
  • Fatigue
  • Scarring of the liver if used long-term

A less common approach for using immunomodulators, but one that's under study, is known as "top down therapy." In this method, you'll get treated aggressively with immunomodulators to get rid of symptoms. Once that's achieved, you'll switch to other types of drugs, like 5-ASAs and antibiotics, for long-term treatment.

You and your doctor can discuss which approach makes sense for you.

What Are Biologics?

Like immunomodulators, biologics are drugs that curb the immune system. They're focused on the inflammation in your gut. These drugs target certain proteins that play a role in inflammation.

Doctors use biologics if you have moderate to severe Crohn's that has not responded well to other medications. They also use it to treat open, draining fistulas.

Some examples of biologics are:

  • Adalimumab (Humira)
  • Certolizumab pegol (Cimzia)
  • Infliximab (Remicade)
  • Natalizumab (Tysabri)
  • Vedolizumab (Entyvio)


Side Effects of Biologics

Due to their targeted nature, biologic treatments tend to cause fewer side effects than other drugs used for Crohn's disease.

Your doctor will still monitor you carefully, especially for signs of infection. Although rare, lymphoma and blood disorders can happen.

Before taking biologics, let your doctor know if you have a heart condition or a disease affecting the nervous system.

You may have side effects at the injection site, such as:

  • Redness
  • Itching
  • Bruising
  • Pain
  • Swelling

Other possible side effects include:

  • Headache, fever, or chills
  • Trouble breathing
  • Low blood pressure
  • Hives or rash
  • Stomach or back pain
  • Nausea
  • Cough and sore throat