What Happens When Your Body Rejects a Transplanted Organ?

Transplant rejection is the body’s natural response to a transplanted organ, where the recipient’s immune system starts attacking the transplanted organ. While the word ‘rejection’ might seem like a dead-end to you, it is not necessarily the case. Timely diagnosis and treatment may prevent organ failure and help avoid severe complications.

Doctors try to minimize the risks of transplant rejection through pre-transplant testing and post-transplant care. Organ rejection can be reversed, and complications can be minimized. This article explores these elements, including the causes of transplant rejection, its types, and the precautions one might take.


What is transplant rejection?

Your body is premeditated to protect itself from foreign, harmful substances, which we call the immune system. Upon recognizing a foreign substance, it attacks them to protect you. Similarly, your body can reject a transplanted organ, deeming it foreign and mismatched.


What causes transplant rejection?

Your immune system constantly searches for and eradicates germs or other foreign substances. It wouldn’t exactly welcome a foreign organ or tissue and will treat the transplanted organs the same way it would treat a harmful microbe.

Your body’s defense system or immune response primarily results in organ rejection. It identifies the transplanted organ as foreign due to mismatched antibodies and sends its antibodies to attack and destroy the organ.


How do doctors minimize the chances of transplant rejection?

There are two ways in which doctors try to prevent your body from attacking the transplanted organ or tissue:


Tissue Typing

Doctors try to find a donor with several biological similarities to the organ recipient. This is called tissue typing: matching the antigens of both the donor and the recipient. Tissue typing is done to prevent the immune response from attacking the transplanted organ.

More similarities mean lesser chances of organ rejection. However, no two people are physiologically the same — except identical twins. So there is no way to ensure the prevention of organ rejection.



People with organ transplants are prescribed lifelong doses of immunosuppressants. These medicines suppress and stop the immune system from attacking the transplanted organ. Missing even one dose of this medicine can result in your body launching an attack on the newly transplanted organ.


Almost 50% of people, especially adolescents, experience organ rejection due to failure to follow the prescribed immunosuppressants.

Types of transplant rejection

Three main types of organ rejection are hyperacute, acute, and chronic. These types are based on your body’s time to reject an organ.


  • Hyperacute rejection occurs immediately, within minutes of transplant, due to the antigens being completely unmatched. It is caused by unmatched blood, and the transplanted organ or tissue is immediately removed to save the recipient’s life.

  • Acute rejection occurs within the first three months of an organ transplant. This is caused by the immune system’s natural response to attack the ‘foreign’ organ or tissue. All patients undergo some form of acute rejection. This is treated by medications that suppress the immune system.

  • Chronic rejection: This is a slow process and can take many years as your body slowly attacks and damages the newly transplanted organ. Over time, the body can develop specialized antibodies to attack the organ, which makes it challenging to treat the problem. Chronic rejection is the leading cause of organ failure

Signs and symptoms of organ rejection

Patients are always advised to strictly follow post-transplant care and be on the lookout for organ rejection.


Some signs and symptoms which may point to organ rejection include:


  • Slowed down the function of the transplanted organ
  • The feeling of discomfort, fatigue, and uneasiness
  • Pain or swelling at the site of the transplant
  • Fever
  • Flu-like symptoms such as chills, body aches, and cough.
  • Sudden changes in weight
  • Sudden changes in heart rates

Symptoms most often depend on the transplanted organ as different organs. For example, patients with kidney transplants who undergo organ rejection are most likely to experience such symptoms as less frequent urination or blood in the urine.


Diagnosis of transplant rejection

As early diagnosis helps prevent the failure of transplanted organs, it is essential to be diagnosed and treated early. Along with tests, monitoring, and biopsy, a hospital will also be required to diagnose organ rejection.

Diagnosing organ rejection requires specialized tests depending on the organ that is being treated. For example, urine and blood tests are carried out to diagnose signs of kidney failure. A biopsy is also needed to confirm any damage to the transplanted organ.


Treatment of Organ rejection

Since the body’s immune system response primarily causes organ rejection, the treatment lies in suppressing the immune system. Most people need to take Immunosuppressants for the rest of their life.


The choice of medicine or dosage depends on how your body responds to the transplanted organ. For example, the dosage might be high if your immune system is actively attacking the organ. Moreover, the doses are initially high and slowly lowered as your body adjusts to the newly transplanted organ.


Unfortunately, organ rejection can still occur even if patients strictly follow the prescribed medication. Acute organ rejection can be managed with high doses of immunosuppressants. Still, hyperacute and chronic rejections generally cannot be reversed and require the removal of the transplanted organ or tissue. Patients will need a new transplant in hyperacute and chronic rejections.


Possible complications

Transplant rejection, if left untreated, results in loss of function and, ultimately, organ failure in the transplanted organ. The administration of significant amounts of immunosuppressants increases the risk of developing cancer and other infections. Additionally, these drugs render the body susceptible to antigens and other potentially severe medication side effects.



Organ rejection is a serious healthcare issue that can be treated or reversed. You should be on the lookout for symptoms and contact your healthcare professionals if you experience any side effects from the medicines. Immediate treatment cannot only prevent organ failure, but it can also help avoid complications that might arise in the aftermath of organ rejection or failure.


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