Chemotherapy involves treating an illness using chemicals. It has long been successful in treating people with cancer. Certain forms of chemotherapy are also effective for autoimmune disorders like Crohn’s disease.


Mercaptopurine, also known as 6-MP, comes in tablet form. It’s one of the more popular chemotherapy treatments for Crohn’s. 6-MP is classified as an antimetabolite, a drug that interferes with metabolic action. Antimetabolites have been effective in treating Crohn’s. They’ve been associated with side effects, too.

The side effects of 6-MP can be challenging to manage. Extreme side effects include a temporary reduction in white and red blood cell counts. This can increase your risk of infection and anemia. Liver and pancreas problems and traditional chemotherapy side effects like nausea and vomiting may occur.


Cyclosporine is also used in chemotherapy. It has been effective in treating Crohn’s. Cyclosporine decreases the body’s immune response. It’s traditionally used to prevent rejection during organ or bone marrow transplants.

Its role is not completely clear in the treatment of Crohn’s. The theory is that it works by changing the activity of the body’s immune response so it lessens inflammation in the gastrointestinal tract.

Some people with Crohn’s experience fistulas. These are abnormal connections in the intestines that can cause discharge, fever, pain, and infections. Cyclosporine has been successful in closing these abnormal openings.

Some of the more severe side effects of cyclosporine include:

  • blood in the urine
  • high blood pressure
  • kidney and liver problems

Cyclosporine is less commonly used to treat Crohn’s because it causes significant side effects.


Methotrexate is another popular Crohn’s treatment. It was originally used for treating breast cancer. Methotrexate is also used as chemotherapy for lymphoma and leukemia. The dosage is significantly lower for treating autoimmune disorders.

Methotrexate is given once a week, either orally or via injection. It blocks cell production, which makes it effective in controlling inflammation caused by Crohn’s disease. Methotrexate’s side effects include a reduction in blood cells produced by bone marrow. This can lead to complications. People taking methotrexate are usually tested regularly to ensure adequate blood counts.

People taking methotrexate will often receive blood tests every two months. These tests check liver and kidney function. Lung scarring is also possible. People may be asked to watch for issues like persistent coughing or trouble breathing. Common side effects include:

  • headache
  • nausea
  • vomiting
  • fatigue

Individuals using methotrexate often have to take a daily dose of folic acid. This helps to counter some of the drug’s side effects.


Infliximab (Remicade) is a TNF (tumor necrosis factor) blocker. It’s used to treat moderate to severe Crohn’s disease. It was initially designed as a chemotherapy drug to treat cancer. TNF is a protein produced by the body when cancer tumors and other medical conditions and infections are present. However, Remicade was not effective in treating cancer.

The drug has been shown to work against autoimmune diseases like rheumatoid arthritis and Crohn’s. These types of medicines are now known as a “biologics” because they work by blocking certain proteins created by the immune system.

Remicade is administered via IV, in a medical facility. The process usually takes several hours. Remicade is often used in more severe cases of Crohn’s. It carries a lymphoma cancer risk, mostly among younger people. It also carries a risk of tuberculosis and fungal infections. These conditions have sometimes been fatal in people with Crohn’s.

Some people have experienced allergic reactions to Remicade. A few people have also reported lupus-like symptoms, including:

  • chest or joint pains
  • shortness of breath
  • rashes

If you begin to experience these side effects, your doctor may choose to change your dosage or take you off the drug.