Radiation therapy is one of the most common and effective treatments for prostate cancer. It uses powerful energy beams, such as X-rays or protons, to destroy cancer cells and stop them from growing or spreading. For many people living with prostate cancer, radiation therapy can help control or potentially eliminate signs of disease, sometimes without the need for surgery.

However, because the prostate is located close to the bladder, rectum, and nerves involved in sexual function, radiation may also affect healthy tissues near the cancer. This can lead to a range of side effects, some mild and short-term, others more serious or longer lasting. Understanding what to expect can help you prepare for treatment and work with your care team to manage symptoms.

In this article, we’ll cover the most common side effects and complications of radiation therapy for prostate cancer, explain why they happen, and share tips to help you feel your best during and after treatment.

What Is Radiation Therapy for Prostate Cancer?

Radiation therapy works by damaging the DNA inside the cancer cells. When the DNA is damaged, these cells can’t divide or repair themselves, and your body removes them over time. There are two main types of radiation therapy for prostate cancer: external beam radiation therapy (EBRT) and brachytherapy.

External Beam Radiation Therapy

With EBRT, a large machine outside your body aims beams of radiation directly at your prostate. Treatments are painless and usually last only a few minutes. Most people have treatments five days a week for several weeks, which gives healthy tissues time to recover between sessions.

Brachytherapy

In brachytherapy, small radioactive seeds are placed inside the prostate. These seeds give off radiation slowly over time, delivering a focused dose directly to the prostate while limiting exposure to nearby organs, such as the bladder and rectum.

In some cases, both types of radiation therapy are used together or combined with hormone therapy to improve results. You may be offered radiation therapy if:

• Your prostate cancer is localized (still within the gland).
• Your cancer has grown just outside the prostate gland into nearby tissue.
• Cancer has recurred (come back) after surgery.

Possible Side Effects and Complications of Radiation Therapy

While radiation therapy can be an effective part of prostate cancer treatment, it — like any cancer therapy — can cause side effects. These can vary from person to person, depending on factors like:

• The type of radiation
• Your overall health
• Other treatments you may be receiving

Below are some of the possible side effects, along with tips for managing them. It’s important to talk with your oncologist or care team about any symptoms you experience, as they can help you find the best ways to manage side effects and maintain your quality of life.

1. Urinary Problems

Radiation can irritate the bladder and urethra (the tube that carries urine out of the body). This irritation, called radiation cystitis, is one of the most common side effects of treatment for prostate cancer. You may notice:

• A need to urinate more often, especially at night
• A sudden urge to pee
• Discomfort or burning when urinating
• Difficulty starting or stopping your urine stream

These symptoms often begin during treatment but can sometimes develop months or even years later. For some people, symptoms improve on their own after treatment ends. Others may need medications or additional support to help manage these side effects.

Tips To Manage Urinary Problems

• Practicing Kegel (pelvic floor) exercises may help you control urine flow.
• Wearing pads or absorbent underwear liners can help with leakage.
• Some people use penile clamps to prevent leakage during activities or special events.
• Talk to your doctor about medications and other options to manage urinary symptoms. Be aware that these treatments can have side effects of their own.

Urinary side effects are slightly more common with EBRT than with brachytherapy, but both types of treatment cause them. Symptoms from brachytherapy are often more noticeable at first, but may improve over time.

2. Bowel Changes

Because the prostate is close to the rectum, radiation therapy can sometimes irritate the bowels, a condition called radiation proctitis. You might notice:

• Diarrhea or loose stools
• More frequent or urgent bowel movements
• Mild rectal pain or burning
• Blood or mucus in your stool

These symptoms usually appear near the end of treatment and often improve within a few months. In some people, bowel irritation may last longer but often can be managed with diet changes or medication.

Tips To Manage Bowel Symptoms

• Limit dairy products like milk, yogurt, and cheese, if they seem to make symptoms worse.
• Avoid foods high in fat or heavy in oils.
• Eat fiber-rich foods, such as lentils, fruits, vegetables, seeds, and nuts, to help support regular bowel function.

Most people find that bowel symptoms get better over time after treatment. In rare cases, some symptoms may be long-lasting.

3. Fatigue

Many people feel unusually tired during or after radiation therapy, and this fatigue may not go away with rest. Fatigue happens because your body is working to repair healthy cells affected by radiation. Emotional stress and the routine of daily treatments can also add to tiredness.

Tips To Manage Fatigue

• Take short walks or do gentle stretching to boost your energy.
• Rest when you need to, but try to keep a regular sleep schedule.
• Eat small, balanced meals and drink plenty of water.
• Ask friends, family, or your support network for help with errands or chores while you recover.

Fatigue is one of the most common side effects of radiation but usually improves within a few weeks after treatment ends.

4. Sexual and Reproductive Side Effects

Radiation therapy can affect the nerves and blood vessels that help you get and keep an erection. You might notice:

• Erectile dysfunction (difficulty getting or maintaining an erection)
• Less firm erections
• Lower interest in sex

Erectile dysfunction can develop gradually, sometimes months or years after treatment. Radiation can also reduce the amount of semen released during orgasm. These changes don’t affect pleasure but can impact fertility (the ability to have biological children).

Tips To Manage Sexual Side Effects

• Talk with your doctor about medications, devices, or other treatments that may help with erections.
• Try pelvic floor exercises to improve blood flow and muscle strength.
• Consider sperm banking before treatment if you hope to have children in the future.
• Share your feelings and experiences with your partner, and talk openly about any physical or emotional changes.

Many people are able to continue a satisfying sex life after prostate cancer treatment, though it may take time for sexual function to recover.

5. Skin and Hair Changes

If you’re receiving EBRT, the skin near the treatment area may become discolored, dry, or itchy, similar to a mild sunburn. This is called radiation dermatitis. Caring for your skin during treatment is important and can help you stay comfortable.

Tips To Care for Your Skin

• Wash the area gently with mild soap and lukewarm water.
• Avoid shaving or using creams and lotions on the treated area unless your care team says it’s safe.
• Wear loose-fitting clothing to prevent irritation.
• Keep the treated area out of direct sunlight.

These effects usually fade within a few weeks after treatment ends, and your skin will gradually return to normal.

6. Long-Term Complications

Most side effects improve over time, but a few can appear months or years after treatment. Thanks to advanced targeting techniques, these are far less common today. Possible long-term complications include:

• Bladder or rectal bleeding
• Urethral stricture (narrowing of the urine passage)
• Rarely, secondary (new) cancers that develop years after treatment

Modern methods like intensity-modulated radiation therapy and stereotactic body radiation therapy deliver radiation with high precision, which helps protect nearby organs. If you experience new or persistent symptoms, your care team can often treat them successfully.

7. Emotional and Mental Health Effects

Cancer treatment doesn’t just affect your body. It can impact your emotions and mental health, too. You may feel anxious, frustrated, or sad, especially as you adjust to changes in your body or daily routine. These feelings are common, and you are not alone.

Ways To Care for Your Emotional Health

• Talk to your doctor or a mental health counselor. Emotional support is part of cancer care.
• Join a prostate cancer support group to connect with others.
• Stay connected with family and friends, even for short check-ins.

Taking care of your emotional health is an important part of recovery and can make it easier to manage physical side effects.

When To Talk to Your Doctor

Always tell your doctor about any side effects you experience during or after radiation therapy, especially if they’re new or getting worse. Many can be treated with medication or lifestyle changes, but your team needs to know what’s happening to help you feel your best.

Join the Conversation

On MyProstateCancerTeam, people share their experiences with prostate cancer, get advice, and find support from others who understand.

Have you experienced any of the side effects of radiation discussed above? Let others know in the comments below.