Radiation Therapy: What to Expect & Possible Side Effects

Radiation therapy uses X-rays to shrink, damage, or kill cancer cells. While modern radiation therapy is designed to target the cancer precisely, healthy cells near the treatment area can sometimes be affected. When healthy cells are damaged, side effects can occur. Advances in planning and delivery have reduced side effects for many patients, and your radiation oncologist will discuss potential risks and benefits with you before treatment so you can choose the best approach together.

What Affects the Severity of Radiation Symptoms?

The effects of radiation vary widely from person to person. Factors that influence the severity of symptoms include:

• The area of the body receiving radiation
• The type of radiation therapy (e.g., external beam, brachytherapy)
• The dose of radiation per treatment and total dose
• Concurrent treatments (chemotherapy, targeted therapy, etc.)
• The patient’s overall health and medical history

Your radiation oncologist will use these factors when designing your individual treatment plan.

What Are the Effects of Radiation Therapy?

Each patient’s experience differs and it’s not possible to predict exactly which side effects you will have. It’s important to report any symptoms you experience to your oncology team. They may pause or change treatment or prescribe medications to help.

Short-term (acute) Effects

Short-term effects can begin during treatment or shortly after and commonly last weeks to months after finishing therapy.

→ Fatigue

Fatigue is the most commonly reported side effect. It is a general sense of tiredness that may not be relieved completely by rest. In many cases it is mild and patients can continue some normal activities; some people continue working full time during treatment.

Management: rest when needed, balance activity with short rest periods, eat a nutritious diet, and reduce stress.

→ Loss of Appetite & Nausea

Radiation near the head, neck, abdomen, or pelvis can reduce appetite and may cause nausea or vomiting for a few hours after treatment. Head or neck radiation can make chewing or swallowing painful.

Management: eat small frequent meals (5–6 daily), keep snacks handy, add calories (butter, milk, cheese) if needed, and speak with a dietitian. If oral intake is insufficient, liquid supplements or a feeding tube may be suggested.

→ Skin Issues

Skin at the treatment site can become sensitive, dry, itchy, red, peel, or blister — similar to a sunburn. Most skin changes resolve after treatment, but some patients have lasting skin discoloration or sensitivity.

Care tips: use lukewarm water and mild soap, avoid harsh products (lotions, perfumes) unless approved by your care team, protect the area from sun, and wear soft, loose clothing.

→ Hair Loss

Radiation causes hair loss only in the treated area. Hair usually regrows after treatment but may be thinner or have a different texture. If the scalp is treated, protect sensitive skin with a loose hat, scarf, or wig.

Long-term (late) Effects

Long-term effects are less common but can develop months to years after treatment. Not every patient will experience them.

→ Mouth & Throat

• Teeth: radiation to the mouth increases risk of tooth decay — get an oral check-up before treatment and remove any decayed teeth if advised.
• Dry mouth: if salivary glands are affected, dryness may persist for months or be permanent.
• Taste changes: food may taste different, sometimes permanently.
• Swallowing: patients may feel a lump or have swallowing difficulties; speech/swallow therapists can help.

→ Bladder, Bowel & Digestion

Radiation to the abdomen or pelvis can cause long-term bladder or bowel irritation, cramps, diarrhea, or, in some cases, rectal inflammation (radiation proctitis) with bleeding or urgency.

→ Infertility & Sexual Health

Radiation to the pelvis or reproductive organs can affect fertility and sexual function.

• Women: vaginal inflammation, stenosis (narrowing), painful intercourse, or early menopause if the ovaries are affected.
• Men: reduced sperm production (temporary or permanent) and possible erectile difficulties.

Fertility preservation options (sperm banking, egg/embryo freezing) should be discussed before treatment when relevant.

→ Secondary Cancer

Rarely, radiation may increase the long-term risk of a second cancer in or near the treated area. This risk is small compared with the potential benefit of curing or controlling the original cancer.

Site-specific Effects

Because radiation is local, side effects usually occur in or near the treated area. Examples include:

Head, Neck & Brain

• Headaches, fatigue, loss of appetite
• Mouth sores, difficulty swallowing, dry mouth, tooth decay
• Hearing loss, jaw stiffness, hair loss on the scalp
• Hypothyroidism, lymphedema (neck swelling), speech or memory difficulties, seizures (rare)

Chest

• Shortness of breath, coughing, trouble swallowing
• Soreness or sensitivity in the breast or chest wall
• Radiation pneumonitis (2 weeks–6 months after treatment) — cough, fever, chest tightness
• Radiation fibrosis (long-term scarring) and possible cardiac effects

Abdomen

• Nausea, vomiting, loss of appetite
• Bowel cramping, diarrhea or constipation
• Possible bladder irritation with pelvic fields

Pelvis

• Diarrhea, rectal bleeding, bladder irritation
• Sexual dysfunction, reduced sperm counts, menstrual changes
• Early menopause or infertility in some patients

When Do Side Effects Start & How Long Do They Last?

Most side effects begin by the second or third week of treatment and often continue for several weeks after the final session. Many patients’ symptoms improve as healthy cells recover; for many people side effects clear within 1–2 months after finishing radiation, though some effects may take longer or, rarely, be permanent.

Practical Tips for Managing Side Effects

If side effects are affecting your quality of life, talk with your radiation oncology team — they can often adjust treatment or prescribe medications to help. Additional general strategies include:

• Maintain a balanced diet: good nutrition helps the body tolerate treatment and recover.
• Get adequate rest: fatigue is common — listen to your body and rest frequently.
• Stay active: gentle physical activity can help reduce fatigue and improve mood and function.
• Join a support group: peer support can reduce feelings of isolation and provide practical tips.
• Consider medications: pain relievers, anti-nausea drugs, or radioprotective agents may be prescribed depending on symptoms and treatment area.

Your Side Effects Treatment Plan

If your care team recommends radiation therapy, remember that side effects vary and are generally manageable. Open communication with your radiation oncologist and oncology nurse is essential — they will monitor symptoms and help you manage them, adjusting the plan if needed to balance effectiveness with quality of life.

Questions or Concerns?

If you have additional questions about radiation and its side effects, contact the Quantum Care Cancer Center Pvt Ltd team and they will do their best to answer questions specific to your situation.

Note: This information is educational and not a substitute for personalized medical advice. Always discuss your specific risks and treatment options with your radiation oncology team.