Side Effects

The side effects you might experience will depend on your general health, the part of the body being treated, the dose and frequency of radiation given, and whether you also receive other systemic treatments concurrently, including hormonal therapy, chemotherapy, targeted therapy, or immunotherapy. Even when two people are receiving the same treatment, each patient may still experience different types, intensities, and frequency of side effects, as each person’s organs can react differently to radiation therapy. As such, you should make sure to remain in close communication with your radiation therapy team to discuss ongoing side effects and management strategies to reduce the impact of these effects on your overall physical and mental functioning.

Side effects from treatment are typically divided into short term and long term side effects. Short term side effects are those that typically develop either during (within 1-2 weeks of starting treatment) or shortly after completion of the radiation therapy course. These side effects are also commonly short lived, and resolve within weeks (up to 3 months) after therapy completion. In contrast, long term side effects are those that develop at least 3 months after completing radiotherapy but occasionally can develop years after treatment. These side effects are often longer lasting and sometimes permanent.

This is a visual side effects chart showing short and long term side effects. Larger bubbles show higher likelihood of occurrence. To see a larger version, click on the chart.

Please note, this list does not represent all of the possible side effects you may experience during your radiation treatment course. Before treatment begins, ask your doctor about possible side effects and how best to manage them.

For patients who prefer to look at the side effects in text instead of graphics, please see below.

Short term side effects

General Effects

• Fatigue (most common)

Fatigue among patients receiving radiation therapy is commonly experienced as physical or mental tiredness that impacts one’s daily functioning and is beyond what one might expect from their normal activity levels. Fatigue is often cited as the most common side effect from cancer treatment and the reasons why patients experience fatigue with radiation therapy are largely unknown. Symptoms often start subtly but progress as radiation therapy continues. Fatigue often peaks near the end of therapy or shortly afterwards and can also continue for months even after radiation therapy is complete. Contributing factors to radiation treatment related fatigue during treatment may include poor appetite and/or nutritional intake, poor sleep habits and hygiene, comorbid conditions, and medications.

Patients often manage fatigue by getting extra rest throughout the day, getting adequate rest at night, eating a balanced diet, and pacing their activities. Maximizing your sleep may involve improving your sleep hygiene, which may include limiting caffeine and alcohol intake and limiting electronic screens close to your bedtime. Additionally, mild to moderate exercise can also help improve symptoms of fatigue, such as taking a short walk each day. Exercise, however, must be balanced with appropriate rest to be maximally effective.

Fatigue must also be distinguished from other medical problems that may have similar symptoms, such as depression, lung and heart issues, liver and/or kidney problems, or diabetes. Please review your symptoms with your radiation oncology team to determine what may be causing your symptoms and which interventions might be right for you.

Genitourinary (GU) Effects

• Urinary frequency, urinary urgency, increased urination at night, pain when urinating (more common)
• Straining to urinate, incomplete bladder emptying (more common)
• Blood in urine (less uncommon)

The most common genitourinary organs involved with radiotherapy for prostate cancer include the urinary bladder, urethra, and prostate. Because the radiation therapy intentionally is delivered to at least some parts of these organs, it is expected these organs will experience some irritation due to the treatment, resulting in some side effects.

Due to irritation at the base of the bladder and urethra within the prostate, some patients experience urinary urgency, an overwhelming sensation of needing to urinate, despite having less than the usual amount of urine in the bladder. This results in patients experiencing urinary frequency and nocturia, the need to urinary more frequently during the day and at night, respectively. Finally, due to the irritation, as urine passes through the urinary channel (urethra), this may elicit pain, called dysuria. The irritation may also cause swelling of the prostate, resulting in a narrowing of the urethra, increased difficulty with voiding, and an inability to completely empty the bladder. Rarely, this irritation in the bladder and/or urethra also produces blood in the urine (hematuria).

Oftentimes, urinary irritation is a completely manageable part of radiation therapy for prostate cancer. For most patients, this results in some mild discomfort, but no specific medications are used. When the symptoms interfere with a patient’s quality of life, your radiation oncologist may recommend an over the counter medication to help with the discomfort, such as Azo (Phenazopyridine), or medicines used for benign prostatic hypertrophy (BPH), such as Flowmax (Tamsulosin). Please discuss these interventions with your radiation oncologist before starting any symptomatic treatment.

Gastrointestinal (GI) Effects:

• Loose stools/diarrhea (more common)
• Rectal urgency (more common)
• Blood in stool (less common)

Anatomically, the bowels sit in close proximity to the prostate gland; in particular, the rectum, sigmoid colon, and small bowel sit in close proximity to the prostate gland. As such, any irritation of these organs may result in gastrointestinal side effects. When radiation irritates the lining of the small bowel, patients may experience loose stools and/or diarrhea. When the lining of the bowel, particularly within the rectum, is severely irritated, this may result in some rectal bleeding.

To ensure you remain healthy, the goal of managing GI side effects is to make sure you do not become dehydrated and you’re able to maintain adequate nutrition. As such, when patients experience diarrhea, the first intervention may include dietary changes, including increasing your fluid intake (to replace the additional fluid losses through your stool) and increasing your intake of foods that promote stool bulking, such as those included in the BRAT diet. If these dietary changes remain ineffective at controlling your symptoms, medication management may be attempted. Initial treatments often start with over the counter medicines, such as Immodium (Loperamide), but may progress to prescription medications. For rectal irritation, patients may be recommended to slow down their bowel movement frequency, which can help with the irritative symptoms. Ultimately, some patients may be asked to use special rectal suppositories to improve the irritation. Please discuss these issues with your physician to learn more and get more specific recommendations. This is especially important if you see new blood in your stool.

Skin Effects

• Skin redness/irritation (more common)
• Hair loss (in the treated area) (common)

External radiation passes through the skin to target your internal structures. Sometimes, the amount of radiation received by the skin is enough to cause side effects to the skin itself, including dryness, redness/erythema, and hair loss within the radiation treatment area.

Note, because radiation is a local treatment, only the skin in the vicinity of the treatment area will be affected. Thus, you will not experience any hair loss on your scalp, chest, or legs due to radiation delivered to your prostate.

During radiation treatments, make sure to pay particular attention to the skin in the area you are receiving treatment. This area may be more sensitive and prone to irritation, so make sure to wash these areas gently with warm water and, if necessary, a soap that is gentle on the skin.

Typically, patients are asked to use moisturizers over the radiation treatment area, to help reduce the side effects that radiation to the skin may cause. Commonly, for areas of skin that are intact, water-based moisturizers are often recommended, such as Aquaphor. For reactions that are more severe, including skin peeling and/or ulceration (rare), other creams such as Silvadine may be recommended. Some radiation oncologists believe that putting any creams, ointments, or moisturizers over the treatment area in the 3-4 hours before your treatment may, paradoxically, increase the radiation reaction. As such, please talk to your radiation oncologist about which product they would like you to use and the recommended area and frequency of application that suits your particular situation.

Long term side effects

Genitourinary (GU) Effects

• Erectile dysfunction (temporary or permanent) (common)
• Urinary frequency/urgency (more common)
• Blood in urine (less common)
• Urethral stricture (less common)

In the first few months after completing radiation therapy, you will likely experience an improvement in the urinary symptoms that first appeared during the radiation treatment. Occasionally, patients continue to have urinary irritation resulting in urinary frequency and urgency. When the diagnosis is unclear, sometimes your doctor may order a urinalysis with urine culture to make sure the symptoms aren’t caused by an infection. When the diagnosis is confirmed, patients are treated with the same interventions that worked during the radiation treatment, including Azo, Oxybutynin, and/or Myrbetriq (mirabegron). If you are experiencing these symptoms, please discuss this with your radiation oncologist and/or urologist.

Patients may also experience blood in their urine after completing radiation therapy. This is most often caused by irritation leading to long term changes in the urinary channel, from the bladder to the penile urethra. Alternatively, one must also consider that these changes are related to a process unrelated to your prostate cancer treatment, and may be caused by issues with your kidneys or ureters. Initially, patients may be asked to submit a urine sample to better understand the contents of your urine and to quantify the amount of blood that is present. After this is done, patients may then be referred to a urologist to perform a cystoscopy, where a camera is used to directly visualize the bladder and urethra, determine the proper cause of the bleeding, and aid in initiation of the appropriate treatment.

Rarely, patients may experience irritation of the urethra that results in a narrowing of urinary passage, known as a urethral stricture. This may result in a weakened urinary stream, painful urinating, and even a urinary tract infection, symptoms that may mimic radiation related bladder and urethral irritation. Once identified, patients with a urethral stricture are often referred to their urologist for additional recommendations. Sometimes, the urologist performs a cystoscopy, which can identify the narrowed urethra. At this point, a therapeutic dilation of the urethra can be performed, which should result in symptomatic relief.

Gastrointestinal (GI) effects

• Rectal urgency (more common)
• Loose stools/diarrhea (more common)
• Rectal bleeding (less common)

Once radiation therapy is complete, radiation related irritation usually subsides within a few weeks to months. Radiation irritation of the small bowel and rectum/colon can, however, cause changes in the lining of these tissues. This can result in long term rectal urgency and loose stools/diarrhea. This may manifest as more frequent bowel movements and loose and/or watery bowel movements. These effects may wax and wane over time in both severity and frequency. Uncommonly, this irritation can lead to long term changes in the structure of these organs, leading to ongoing rectal bleeding.

Initial treatments of rectal effects often depend on the severity of the symptoms. Mild symptoms can be treated with behavioral and dietary modifications, including long term alterations to your diet. If these symptoms persist, particularly in the setting of rectal pain and/or bleeding, one may consider specialized rectal suppositories. Ultimately, refractory symptoms or symptoms unexplained by an external examination (such as bleeding caused by hemorrhoids) may require a referral to a gastroenterologist, who may perform a colonoscopy and directly visualize the internal lining of the colon. Further treatments may be based on the findings identified at the time of the procedure.