Possible Side Effects of Radiation Treatment for Prostate Cancer

Author: OncoLink Team
Last Reviewed: April 03, 2025

The radiation used to destroy cancer cells can also harm normal cells in the nearby area. Side effects from radiation treatment are related to the area of the body being treated. 

When do side effects often happen?

Side effects may start happening after a few weeks of treatment. Most side effects are temporary (short-term) and slowly start to go away once treatment is done. While side effects may be unpleasant, there are treatments to help deal with them.

You will be seen by your radiation oncology providers often during treatment. These visits are a chance to ask questions and to talk about any side effects and how to best manage them. You can also call your providers to speak about any side effects.

Short-Term Side Effects

Any type of radiation therapy (external beam or brachytherapy) to treat prostate cancer can cause side effects. Short-term side effects are ones that start during or shortly after your radiation treatment. Below is a list of possible short-term side effects. Treatments can affect each patient differently, and you may not have these specific side effects. Talk with your care team about what you can expect from your treatment.

  • Skin irritation in the treatment area is common. It may become red, irritated, dry, or sensitive. This may start to look like a sunburn. Treat the skin gently to avoid further irritation, and bathe carefully, using only warm water and mild soap. Do not use scented lotions or soaps, as these may cause more irritation.
  • Fatigue is very common with radiation treatment and tends to start a few weeks into therapy. Fatigue often goes away slowly over the weeks and months after treatment.
  • Irritation of the rectal and urinary tract tissue can cause changes to your bowel and urine habits. It can cause urinary urgency, urinary frequency, nocturia (waking up at night to go to the bathroom), diarrhea, incontinence, or pain with bowel movements or urination (dysuria). These symptoms tend to get better within a few weeks of finishing treatment. Drink plenty of fluids. Talk to your provider about ways to manage these symptoms. In some patients, these problems can last after treatment.
  • Loss of hair in the pelvic area. Hair typically starts to regrow a month or so after treatment. However, your hair might not grow back exactly as it was before treatment and for some, the hair may not ever grow back.
  • Reduced blood counts, including neutropenia, anemia, or thrombocytopenia (low platelet count).

Late Effects

Late effects can happen months to years after cancer treatment has ended. The risk of late effects depends on the areas included in the field of radiation and the radiation techniques that were used. Some of the potential late effects of radiation to the prostate include:

  • Most men will be sterile (unable to have children) after radiation treatment for prostate cancer. Talk to your oncology team about sperm banking if you wish to have a child in the future.
  • Erectile dysfunction or dry orgasm can occur after radiation therapy. For some men, medications or other treatments can help. A couple’s therapist can also help you and your partner cope with these changes in your relationship.
  • Bladder problems, like incontinence (not being able to hold your urine in), hemorrhagic cystitis (blood in the urine), urinary tract infections, and bladder cancer may happen. If you notice any changes in your bathroom habits or urine, call your provider.
  • Gastrointestinal (stomach and bowel) problems can include strictures, blood in the stool, chronic diarrhea, and colon cancer.
  • There is a low risk of developing a second cancer in or near the radiation field. These are called secondary cancers, and they happen because of the exposure of healthy tissue to radiation. Modern radiation techniques are designed to limit this exposure.
  • Lymphedema, which is swelling, can occur if the lymph nodes have been damaged. If you notice any new swelling in your groin, legs, or feet, call your provider right away.
  • You might have permanent (lifelong) skin changes in the area that was exposed to radiation.

You may not have any side effects or late effects of radiation treatment. But if you do, it is important that you speak to your provider about how to best manage these side effects. After treatment, talk with your oncology team about receiving a survivorship care plan, which can help you manage the transition to survivorship and learn about life after cancer.

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