How Do Immunosuppressants Work?

Reviewed on 7/27/2021


Immunosuppressants are a class of drugs used to treat and prevent certain medical conditions, including autoimmune diseases (disorders that cause abnormally low activity or overactivity of the immune system) such as psoriasis (an immune-mediated disease that causes raised, scaly patches on the skin because of systemic inflammation), rheumatoid arthritis (a condition in which the body attacks its own joints causing pain, swelling, and loss of function), lupus, leukemia (cancer that begins in the white blood cells), and organ transplantations. These drugs inhibit or prevent the activity of the immune system. A few drugs belonging to this class are used to prevent the rejection of a transplanted organ, such as the liver, heart, or kidney; these drugs are called antirejection drugs.

The immune system is a complex network of cells, tissues, and organs. Together, they help the body fight infections and diseases. In conditions such as an autoimmune disease or organ transplantation, the immune system mistakenly considers healthy tissues and cells to be foreign invaders (virus, bacteria, parasites, chemicals, and toxins) and mounts an attack when there is no invader or does not stop an attack after the invader has been killed. These activities result in autoimmune diseases, allergic reactions, and organ transplant rejection.

Immunosuppressants are prescription-only medicines and are administered as a powder to be mixed with sterile water to be given intravenously (into a vein) and as a solution (liquid) in a prefilled syringe or an autoinjector to be given subcutaneously (under the skin).

Immunosuppressants work in the following ways:

  • They suppress or inhibit the immune system’s activity and prevent it from attacking the transplanted organ, as it attacks any foreign cells, which could otherwise lead to severe damage to the organ.
  • They stop the immune system from damaging healthy cells and tissues.
  • They work by blocking the activity of T-cells (a type of white blood cell) that directly attacks and eliminates foreign molecules from the body.
  • These drugs target intracellular signaling pathways induced by the activation of T lymphocytes or T-cells. 
  • They inhibit calcineurin (an enzyme that activates T-cells of the immune system) and thus inhibit the function of T-cells.
  • In addition, they reduce the immune system’s ability to attack the body tissues in some cases of autoimmune diseases (a condition in which the immune system mistakenly attacks the healthy cells in the body).


The term arthritis refers to stiffness in the joints. See Answer


Immunosuppressants are used in conditions such as:


Common side effects include:


Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.


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Generic and brand names of immunosuppressants include:


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