Radiation therapy for prostate cancer can cause short-term side effects such as diarrhea, urine changes, and more. Long-term side effects such as urinary and bowel problems may also occur.

Radiation therapy can be potentially lifesaving, but it can also cause short-term or long-term side effects.

Your doctor can provide you with more information about the possible side effects based on the type of radiation treatment, and discuss the benefits of the treatment.

Read on to learn about some of the potential side effects of radiation treatment for prostate cancer and how long you can expect them to last.

Radiation therapy side effects often start in the second or third week of your treatment. Some side effects can occur immediately after or days after radiation. Some side effects may worsen the further into treatment you are.

External beam radiation therapy side effects

External beam radiation therapy can lead to:

Brachytherapy side effects

Potential side effects of brachytherapy include:

  • bowel problems
  • urinary problems
  • erectile dysfunction

If you receive high-dose brachytherapy, you may have pain or swelling between your scrotum and rectum. Your urine may also turn reddish-brown.

If you have low-dose brachytherapy, there’s a risk of:

  • setting off airport detection systems
  • seeds passing out of your body through your urine
  • seeds moving through your bloodstream to other areas

Your doctor may advise avoiding contact with pregnant people or small children while you have seeds implanted, since you may give off a small amount of radiation.

Radiopharmaceutical side effects

Potential side effects of radiopharmaceuticals include weight loss and weakness as a result of radiation exposure, as well as:

Most radiation therapy side effects go away after weeks to months, but some can last longer. Some may not develop until months or even years after your treatment.

Long-term side effects can include:

Fatigue might linger after your therapy for weeks to months after treatment.

Radiation therapy and risk of a second cancer

Radiation therapy can damage cells around the area being treated and slightly increase your risk of developing another cancer.

Research suggests radiation therapy for prostate cancer increases your risk of rectal cancer or acute myeloid leukemia.

It’s thought that the risk of a second cancer becomes higher with increasing dosages of radiation.

Radiation therapy can be lifesaving for some people with prostate cancer. For people who need it, the advantages can outweigh the risk of side effects.

A doctor can help you weigh the pros and cons of radiation therapy and help you decide if you may benefit more from another treatment option such as surgery or monitoring the growth of the cancer.

There are three main types of radiation therapy: brachytherapy, external beam radiation, and radiopharmaceuticals.

Brachytherapy involves inserting radioactive pellets into your prostate. External beam radiation involves aiming radiation at your prostate from an external device. Radiopharmaceuticals involve taking radioactive medication through an intravenous (IV) line that travels through your bloodstream.

Some common side effects of radiation therapy for prostate cancer include:

  • bowel changes such as diarrhea
  • urinary changes such as frequent urination
  • erectile dysfunction
  • fatigue

Other side effects can also occur. It’s best to let your doctor know about any side effects you experience.

Radiation therapy is one of the most common treatments for prostate cancer. It can be lifesaving for people who need it, but can also cause many different side effects.

Some of the most common side effects of radiation therapy for prostate cancer include erectile dysfunction, urinary problems, and bowel problems. These side effects usually pass after weeks or months but can become long-term problems for some people.

Your doctor can provide more information about the side effects you may experience based on the type of radiation therapy. They can also help monitor and treat any side effects that do develop.