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Does everyone have side effects from radiation?

Radiation therapy is an important treatment option for many types of cancer. It uses high-energy radiation to kill cancer cells and shrink tumors. Radiation can be delivered externally through a machine outside the body, or internally through radioactive material placed inside the body near cancer cells.

While radiation therapy is effective at treating cancer, it can cause side effects because it also damages some healthy cells in the treatment area. Not everyone experiences the same side effects from radiation therapy. The type and severity of side effects depends on many factors like the area being treated, radiation dose, patient’s health, and more.

Some common questions about radiation side effects include:

Does every patient get side effects from radiation therapy?

No, not every patient experiences significant side effects from radiation treatment. Some people complete radiation therapy with minimal side effects, while others may experience more bothersome acute side effects like skin irritation, fatigue, nausea, etc.

According to Cancer Research UK, around 85% of people who have radiation therapy experience some acute side effects. But only around 10-15% of people find these acute side effects significantly affect their quality of life.

So while most patients do get some side effects, only a minority have severe reactions that disrupt their daily activities or quality of life. With medications and care from your radiation oncology team, many side effects can be prevented or managed effectively.

What factors affect which side effects and how severe they are?

The likelihood and severity of side effects depends on several factors:

– Area being treated – Some parts of the body are more sensitive to radiation. For example, treatment to the digestive or urinary tract is more likely to cause nausea, diarrhea, or bladder irritation. Treatment to the head/neck area can affect salivary glands and cause dry mouth.

– Total radiation dose – Higher doses increase risk of side effects. Doses are often split into smaller fractions to reduce risk.

– Fractionation – Smaller daily doses over many sessions typically causes less severe effects compared to one large dose.

– Beam energy – Higher energy beams can penetrate deeper but also increase damage to surrounding healthy tissue.

– Beam direction – Advanced techniques like IMRT maximize dose to the tumor while reducing exposure to nearby organs.

– Individual variation – Each person responds differently based on their genetics, health, medications, and other factors. Age, kidney function, and other diseases like diabetes also impact sensitivity to radiation.

– Lifestyle factors – Smoking, alcohol, medications, diet and supplements can influence side effects.

By considering these factors, radiation oncologists prescribe the optimal dose, fractionation schedule, and technique to target the tumor effectively while minimizing side effects.

Do side effects appear while undergoing treatment or after?

Patients can experience side effects both during and after radiation treatment:

– Acute side effects – These occur during treatment and shortly after, typically resolving within weeks or months of finishing radiotherapy. Examples include skin irritation, fatigue, nausea, diarrhea, and swelling/irritation of treated areas.

– Late side effects – These develop months or years after radiation and are often permanent. Examples include skin scarring and discoloration, stiffness in treated areas, lymphedema, and organ damage. Certain late effects like radiation-induced second cancers are still uncommon with modern techniques.

– Cumulative side effects – Some side effects like fatigue and appetite changes build up progressively over the course of treatment due to accumulating radiation dose.

Radiation oncologists follow up closely with patients during and after treatment to monitor, prevent, and manage both acute and late side effects. Let your care team know if any side effects develop or worsen so they can adjust your treatment if needed.

Common Side Effects

While specific side effects depend on the area being treated and other factors, some of the most common overall side effects across all types of radiation therapy include:


Fatigue is one of the most frequent side effects, reported in up to 80% of patients. It develops gradually as treatment sessions accumulate. Fatigue results from the cumulative effects of radiation on various tissues and the body’s efforts to repair this damage. Staying active, allowing rest periods, managing other side effects, and receiving support can help manage fatigue.

Skin Irritation

External beam radiation can irritate and burn skin and tissues in the treatment area, causing redness, dryness, swelling, peeling, or blistering. Keeping the area clean and moisturized can soothe skin irritation. Inform your care team about any skin reactions so they can provide topical treatments and adjust the radiation dose/technique if needed.

Hair Loss

Radiation beams focused on areas with hair follicles may cause hair loss. For example, radiation to the head often causes localized bald patches. Hair regrows several months after completing treatment but may initially have a different color or texture. Wigs, hats, or scarves can help manage hair loss.


Radiation to the stomach, abdomen, brain, or with chemotherapy may cause nausea and vomiting. Anti-nausea medications given before each treatment and for a few days after can effectively prevent or treat nausea in most patients.


Abdominal radiation can irritate the bowel and cause diarrhea, cramping, or other digestive issues. Medications, diet changes, hydration, and probiotics can help manage diarrhea. Notify your care team if diarrhea persists or worsens.

Difficulty Swallowing

Head and neck radiation can cause swelling, dry mouth, and scarring that makes swallowing difficult and painful. This may require switching to soft, moist foods or liquid supplements. Most swallowing problems improve over time after treatment ends.

Sexual Side Effects

Radiation to reproductive organs, the pelvis, bladder, or rectum can affect sexual health and fertility. For example, radiation may lower testosterone levels and sperm production in men. Vaginal dryness, scarring, and early menopause can occur in women. Discuss family planning and preserving fertility before treatment. There are ways to prevent or manage many sexual side effects.

Bladder Irritation

Abdominal or pelvic radiation may inflame the bladder lining, causing stinging during urination and an urge to urinate frequently or urgently. Drinking extra fluids, prescription medications, and time typically improve bladder irritation after completing treatment.

Swelling (Edema)

Radiation can damage lymph nodes and vessels, leading to fluid buildup and swelling in nearby areas like the legs, face, arms, or around the tumor site. Elevating affected areas and wearing compression garments can help reduce swelling. Inform your care team about any swelling.

Cognitive Changes

Radiation to the brain or with certain chemotherapy drugs may cause headaches, fatigue, concentration and memory difficulties (sometimes called “chemo brain” or “radiation fog”). These cognitive side effects often improve over time after treatment ends. Get extra rest, stay organized, and use memory aids.

Low Blood Cell Counts

Radiation affects bone marrow and blood cell production. You may develop low counts of infection-fighting white blood cells (neutropenia), anemia, or bleeding/bruising if platelet counts drop. Your care team will monitor your blood regularly and manage these side effects with transfusions, growth factors, or medication adjustments.


Buildup of lymph fluid (lymphedema) can occur when radiation damages lymph nodes and vessels that drain fluid from tissues. It commonly affects the arms or legs. Wearing compression sleeves and gently exercising the affected limb can help manage lymphedema. Inform your care team about any swelling or heaviness in your limbs.

Scarring and Stiffness

Radiation can cause scar tissue formation in treated areas. This can lead to skin discoloration or tightening/restricted motion in areas like the neck, chest, or joints. Gentle stretching and exercise may improve range of motion over time. Moisturizing and massaging irradiated skin may keep it supple.

Risk Factors for Side Effects

While most patients experience at least some mild side effects, certain factors can increase the risk of more severe reactions to radiation therapy:

– High radiation dose – Larger total doses increase risk.

– Large treatment area – Wide radiation fields affect more tissue.

– Sensitive body site – The head, neck, chest, and pelvis are quite radiation-sensitive.

– Younger or older age – The very young and very old are more susceptible.

– Poor nutrition and hydration – Adequate food and fluids help tolerate treatment.

– Poor overall health – Pre-existing illness or frailty reduces tolerance.

– Other medical conditions – Diabetes, autoimmune disorders, kidney disease, etc.

– Previous radiation – Re-irradiation causes cumulative damage.

– Other cancer treatments – Some chemo, surgery, or immunotherapy side effects overlap.

– Medications – Some drugs interact and worsen radiation effects.

– Genetic factors – DNA repair disorders increase radiosensitivity.

– Lifestyle habits – Smoking, excess alcohol, and stress worsen effects.

By controlling these factors when possible through personalized care, oncologists aim to maximize the radiation dose to cancer cells while keeping side effects at an acceptable level.

Preventing and Managing Side Effects

While some side effects are unavoidable, many can be prevented or effectively managed with proper care. Here are some strategies:

Careful Treatment Planning

Radiation oncologists use 3D imaging and planning software to precisely target the tumor while sparing surrounding normal tissues. Advanced techniques like IMRT, proton beam, and stereotactic radiosurgery minimize side effects.

Gradual Dose Buildup

Total radiation dose is divided into smaller daily doses called fractions. Typically 30-40 fractions are given over several weeks. This fractional approach allows normal tissues time to repair between treatments while cumulative damage builds up in cancer cells.

Supportive Medications

Your oncologist may prescribe medications before, during, and after treatment to prevent side effects like nausea, vomiting, diarrhea, swelling, and skin irritation. Speak up about any side effects so they can be treated promptly.

Dietary Changes

Your doctor or nutritionist may recommend changes to your diet and fluids to reduce side effects. For example, bland, low fiber foods can reduce diarrhea, while hydration and electrolytes combat dehydration and fatigue. Don’t try any restricted diets without medical supervision.

Skin Care

Gently wash and moisturize irradiated skin to prevent drying and breakdown. Wear loose cotton clothing over treatment areas. Use only recommended lotions or topical treatments. Avoid exposing treated skin to sun.

Oral Care

If the mouth or throat are in the treatment area, practice good oral hygiene with soft toothbrushes, alcohol-free mouth rinses, and moisturizing gels to prevent gum and mouth sores. Avoid irritants like tobacco, alcohol, and spicy foods.

Fatigue Management

Balance rest periods with light activity to avoid debilitating fatigue. Try short walks, gentle stretching or yoga, relaxation techniques, and allowing time for adequate sleep. Save energy for important tasks.

Follow-up After Treatment

Your radiation oncology team will meet with you regularly after you complete radiotherapy to monitor and manage any side effects, as well as check for cancer recurrence. Report any new or concerning symptoms promptly. Lifelong follow-up care is important after cancer treatment.

Tracking side effects helps your doctors adjust your care plan. Keep a diary noting when side effects occur, what aggravates or relieves them, how severe they are, and how they impact your functioning. This helps your team provide the best supportive care possible.

When to Call Your Doctor

Contact your radiation oncology team right away if you experience:

– Severe skin reactions like blistering, peeling, or bleeding

– Difficulty swallowing or breathing

– Severe nausea, vomiting or diarrhea preventing food/fluid intake

– Significant swelling or urinary symptoms

– Unexplained fever, chills, cough, or other signs of infection

– Uncontrolled pain or discomfort

– Excessive fatigue limiting self-care

– Emotional distress, depression, or anxiety interfering with treatment

– Any other side effects concerning you or significantly affecting your quality of life

Your doctors want to help you feel as well as possible before, during, and after radiation therapy. Speak up when side effects occur and work collaboratively with your care team to find solutions. This will give you the best chance of completing radiation treatment on schedule and with minimal impact on your daily life.


While most patients undergoing radiation therapy experience at least some minor side effects, the level of severity varies based on the treatment area, radiation dose, individual risk factors, and use of preventive measures. Speak with your radiation oncologist about your personalized risk of side effects and how to prevent or manage them. Staying active, hydrating, eating well, and following skin care measures can reduce many radiation side effects. Report any worrying symptoms promptly so your care team can respond effectively. This collaborative approach gives you the highest chance of tolerating radiation therapy well and achieving the best possible treatment results.