Common Side Effects from Radiation Therapy

Side Effects and How To Manage Them

Your radiation doctors plan treatments very carefully to lessen side effects. While some patients have little or no side effects from radiation therapy, others feel some discomfort. Side effects are usually short-term and can be treated. No matter what type of therapy you receive, our doctors and nurses are skilled in helping to manage side effects.

Side effects most often start by the second or third week of treatment. They can last up to several weeks after your final radiation treatment. Many people who get radiation have some fatigue and skin reactions. Based on the area of your body being treated, you may also have some:

  • Hair loss
  • Appetite changes
  • Mouth and throat changes
  • Trouble swallowing
  • Swelling
  • Coughing
  • Diarrhea
  • Nausea and vomiting
  • Urinary and bladder changes
  • Sexual changes

Most side effects go away within 1–2 months after you have finished radiation therapy.

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Skin Reactions
Hair Loss
Appetite Changes
Mouth and Throat Changes
Nausea and Vomiting
Sexual Changes Changes


You may feel more tired than normal during treatment. The cancer itself or radiation therapy may be the cause. Your body is working hard to heal itself. To help with fatigue:

  • Go for a short walk, ride a bike, or do yoga. If you were physically active before starting radiation treatment, try to keep up your current exercise routine, or adjust it as you start to feel fatigue. Research shows that most people feel better when they get some exercise each day.
  • Plan tasks for times when you have the most energy. Finish only what you can and let others help you with the rest.
  • Plan time to rest. Take short naps or breaks between activities. Relax before bed so you can sleep better. Read or listen to soothing music. Try to get a good night’s sleep.
  • Keep track of how you feel each day. Keeping a record will help you plan how to best use your time. Share your record with your nurse. Let your doctor or nurse know if you notice changes in your energy level, such as whether you have lots of energy or feel tired.
  • Try eating 5–6 small meals each day rather than three large ones. Eat foods that are easy to x, such as canned soups, frozen meals, yogurt and cottage cheese. Drink plenty of uids (about eight cups of water or juice) each day.
  • Talk with your doctor or nurse. He/she can suggest treatments for problems that may be causing your fatigue, such as anemia (a problem in which the number of red blood cells is below normal), depression or trouble sleeping.

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Skin Reactions

Radiation can affect healthy skin cells in the treatment area. When people get radiation almost every day, their skin cells may not have enough time to recover between treatments. Skin changes can happen any place on the body that gets radiation. Reactions are like mild sunburn. Some common skin changes you may have include dryness, redness, itching, peeling, sores, ulcers and swelling. Your skin may darken in that spot. Most skin changes heal and fade within a few weeks of stopping treatment.

Caring for Your Skin after Radiation

When you shower/bathe, do not scrub the treatment area. Only use mild soaps (like Dove) that are free of harsh chemicals or fragrances. Dry yourself with a soft towel by patting, not rubbing, your skin. Be careful not to wash of the ink markings needed for radiation therapy.

Apply moisturizing lotion to your skin. Ask a member of your care team which lotion to use. Do not put lotion on the treatment area before treatment. Wait until after you have been treated and apply as you like. Check with your doctor or nurse before using:

  • Bubble bath
  • Makeup
  • Cornstarch
  • Oil
  • Cream
  • Ointment
  • Deodorant
  • Perfume
  • Hair removers
  • Soap
  • Powder
  • Sunscreen

Other tips include:

  • Avoid sun on the treated area. Ask your care team about using sunscreen.
  • Protect your skin from heat or cold. Do not use tanning beds, hot tubs, saunas, hot pads and ice packs.
  • Wear soft, loose clothing to avoid rubbing irritated skin.
  • Do not shave in the area being treated unless your doctor says it is okay.
  • Do not use tape or adhesive bandages on the treatment area.
  • For anal skin irritation, clean the area with unscented baby wipes or water from a spray bottle and avoid excessive wiping.
  • Talk with your care team if you have any problems or questions about your skin.

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Hair Loss

Hair loss from radiation therapy happens only on the part of your body being treated. This is not the same as hair loss from chemotherapy, which happens all over your body. You may start losing hair in your treatment area 2–3 weeks after your first radiation therapy session. It takes about one week for all hair in your treatment area to fall out. Your hair may grow back in the months after treatment is over. Sometimes, however, the dose of radiation is so high that your hair may never grow back. Once your hair starts to re-grow, it may not look or feel as it did before. It may be thinner or curly instead of straight, or it may be darker or lighter in color.

What to Do Before Hair Loss

Decide whether to cut your hair or shave your head before you lose your hair. If you decide to shave your head, the best time to do so would be before starting radiation treatment. This is so we do not have to remake your mask if the it changes.

If you plan to buy a wig, do so while you still have hair. The best time to select a wig is before or soon after radiation therapy begins. This way, your wig will match the color and style of your own hair. Choose a wig that feels comfortable and does not hurt your scalp. Ask your doctor or nurse about Boo’s Boutique, found on the first floor of Fox Chase. Boo’s Boutique specializes in helping patients make decisions about wigs.

Caring for Your Hair After Radiation

  • Gently wash your hair using a mild shampoo, such as a baby shampoo. Use a soft towel to dry your hair by patting and not rubbing.
  • Do not use items that can hurt your scalp, such as:
  • Straightening or curling irons
  • Brush rollers or curlers
  • Electric hair dryers
  • Hair bands and clips
  • Hair sprays
  • Hair dyes
  • Do not use products to perm or relax your hair or hair weaves and extensions.
  • Do not use harsh products, like gel, mousse, oil, grease or pomade, during treatment.

After Hair Loss

Protect your scalp, which may feel tender after hair loss. When outdoors, protect against cold and sunburn by covering your head with a hat, turban, scarf or wig.

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Appetite Changes

Your body uses extra energy to heal during radiation therapy. It is important to eat enough calories and protein and drink adequate fluids to maintain your strength and weight during this time. You may notice changes in your eating habits. You may lose your appetite, food may taste different, or you may find it hard to eat. Think of healthy eating as part of your treatment. Talk to your care team if you are having eating issues. You may be referred to a nutritionist, a professional who specializes in food planning.

Try these tips:

  • Eat slowly.
  • Eat more food during the times you are feeling better.
  • Eat small meals throughout the day instead of a few big meals.
  • Ask others to eat with you. This can make meal times more pleasant.
  • Drink plenty of water and other fluids.
  • Check with your doctor before taking vitamins (especially in high doses), herbal remedies or other supplements.
  • Have easy-to-make foods on hand for when your energy level is low.
  • Get plenty of protein and calories. These help your body to heal, keep your muscles from weakening, and provide fuel.

Some common high-protein foods include:

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Mouth and Throat Changes

Radiation therapy to the head and neck can cause mouth changes. Radiation not only kills cancer cells but can also harm healthy cells in the glands that make saliva and the moist lining of your mouth. You may have:

  • Mouth sores
  • Tooth decay
  • Jaw stiffness
  • Infection to gums/teeth/tongue
  • Dry mouth
  • Loss/change in taste
  • Thickened saliva

Some problems, like mouth sores, may go away after treatment ends. Others, such as taste changes, may last for months or even years. Some problems, such as dry mouth, may get better but never go away.

Mouth Care After Radiation

  • Visit your dentist before starting radiation to finish any dental work and make sure your mouth is as healthy as possible.
  • Keep your mouth moist by drinking water, sucking ice chips, chewing sugar-free gum, or sucking sugar-free hard candies. Your doctor may also suggest that you use a saliva substitute or prescribe medicine to help increase saliva.
  • Check your mouth each day to spot problems as soon as they start. Look for mouth sores, white patches or areas of irritation.
  • Keep your mouth, teeth, gums and tongue clean.
  • Brush with an extra-soft toothbrush after every meal and at bedtime.
  • Use fluoride toothpaste. Your doctor may prescribe special fluoride gel.
  • Floss gently daily. If your gums bleed or hurt, stay away from those areas.
  • Rinse your mouth every 1–2 hours with a salt and baking soda rinse. Mix 1/4 teaspoon baking soda and 1/8 teaspoon salt in one cup of warm water.
  • If you have dentures, make sure they fit well, and clean them by soaking or brushing them each day.
  • Exercise your jaw muscles three times a day by opening and closing your mouth 20 times as far as you can without pain.
  • Let your doctor know if your mouth hurts. Your doctor may need to prescribe medicine to help control mouth pain.

Your Throat

Radiation therapy to the neck or chest can cause the lining of your throat to become swollen and sore. Your risk for throat changes depends on how much radiation you are getting, whether you are also having chemotherapy, and whether you use tobacco and alcohol while getting radiation therapy. You may notice throat changes in 2–3 weeks after starting radiation. These will likely get better 4–6 weeks after you have finished treatment.

Nutrition During Head, Neck or Chest Radiation

  • Be careful of what you eat when your mouth is sore. Choose foods that are easy to chew/swallow, such as foods that are soft, moist or wet. Sip liquids with meals.
  • Choose foods/drinks high in calories and protein. (See the list under “Appetite Changes” on page 16.) When it hurts to swallow, you may eat less and lose weight. It is important to maintain your weight during radiation therapy.
  • Eat small meals and snacks 5–6 times a day, instead of three large meals each day.
  • Avoid sharp or crunchy foods, food/drinks high in sugar and acidity, hot or spicy foods, and alcohol and tobacco products.
  • Sit upright and bend your head slightly forward when eating. Do not lie down or recline for at least 30 minutes after eating.
  • Talk to your care team if you are having difficulty swallowing or experience choking and coughing while eating.

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Coughing, often a symptom of your disease, may be caused by cancer treatment, especially radiation to the chest.

  • Medicine may be prescribed depending on the severity of your cough.
  • Stay hydrated by drinking 6–8 glasses of water per day.
  • Use a humidifier to help a dry cough.
  • Do not smoke, as smoking can worsen a cough.

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Radiation therapy to the pelvis, stomach and abdomen may cause diarrhea. People get diarrhea because radiation can irritate healthy cells lining the inside of the bowel. These areas are sensitive to the amount of radiation needed to treat cancer.

  • Stay hydrated. Drink 8–12 cups of clear liquids daily. Water is preferred; avoid liquids high in sugar. Severe diarrhea can cause dehydration, which may become serious and require intravenous fluids. Our team will monitor you closely for dehydration.
  • Eat small meals and snacks rather than three large meals.
  • Eat foods high in salts, such as sodium and potassium. Your body can lose these salts when you have diarrhea, and it is important to replace them. Try bananas, oranges, peaches and apricot nectar, as well as boiled or mashed potatoes.


  • Alcohol
  • Milk and dairy foods
  • Spicy foods
  • Foods or drinks with caffeine
  • Foods or drinks that cause gas
  • Foods high in fiber
  • Fried or greasy foods
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  • Eat low- fiber foods. High- fiber foods can worsen diarrhea.
  • Take care of your rectal area. Your doctor or nurse may suggest an ointment to help with discomfort. Instead of toilet paper, use a baby wipe or squirt water from a spray bottle to clean yourself after bowel movements. Ask your nurse about sitz baths.
  • Talk with your care team if you are having diarrhea. They may suggest taking a medication, such as Immodium, to help.

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Nausea and Vomiting

Nausea and vomiting can occur after radiation therapy to the stomach, small intestine, colon or parts of the brain. Your risk for nausea and vomiting depends on how much radiation you are getting, how much of your body is in the treatment area, and whether you are also having chemotherapy.

To prevent nausea and vomiting:

  • Eat and drink bland, easy-to-digest foods and drinks that do not upset your stomach, such as toast, gelatin and apple juice.
  • You may feel less nausea if you relax before each radiation therapy treatment.
  • Learn the best time for you to eat and drink. Try a light snack, such as crackers and apple juice, 1–2 hours before radiation therapy. Or, you may feel better if you have treatment on an empty stomach.
  • Eat small meals and snacks. Eat slowly and do not rush.
  • Have foods and drinks that are at room temperature (not too hot or cold).
  • Talk with your doctor or nurse. He/she may suggest a special diet or prescribe medicine to help prevent nausea.
  • Ask your doctor or nurse about acupuncture, which may help relieve nausea and vomiting caused by cancer treatment. Acupuncture, a type of complementary and alternative medicine, involves inserting thin needles through the skin at specific points on the body.

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Urinary and Bladder Changes

Radiation therapy to the pelvis can cause urinary and bladder problems by irritating the healthy cells of the bladder wall and urinary tract. These changes may start 3–5 weeks after radiation therapy begins. Most problems go away 2–8 weeks after treatment is over. You may experience:

  • Burning or pain when you begin to urinate or after you urinate
  • Trouble starting to urinate
  • Trouble emptying your bladder completely
  • Frequent, urgent need to urinate
  • Inability to control the flow of urine from your bladder
  • Waking frequently to urinate
  • Blood in your urine
  • Bladder spasms, which are like painful muscle cramps

Ways to manage include:

  • Drink lots of fluids. Aim for 6–8 cups of fluids each day, or enough that your urine is clear to light yellow in color.
  • Avoid coffee, black tea, alcohol, spices and all tobacco products.
  • Talk with your doctor or nurse if you think you have urinary or bladder problems. You may need to provide a urine sample to check for infection.
  • Talk with your doctor or nurse if you have incontinence. He/she may refer you to a physical therapist to assess your problem. The therapist may recommend exercises to help you improve your bladder control.
  • Your doctor may prescribe medications to help you urinate, reduce burning or pain, and ease bladder spasms.

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Sexual Changes

Sexual and fertility changes can happen when people have radiation therapy to the pelvic area. For women, this includes radiation to the vagina, uterus or ovaries. For men, this includes radiation to the testicles or prostate. In men and women, changes may be seen with rectal or bladder treatment. Scar tissue from radiation therapy can cause many sexual side effects. Other problems, such as fatigue, pain, anxiety or depression, can also affect your interest in having sex. Some sexual and fertility changes you may experience include:

In Women

  • Pain during sex
  • Vaginal stenosis (narrowing)
  • Infertility
  • Vaginal itching and dryness
  • Symptoms of menopause

In Men

  • Impotence (inability to keep erection)
  • Inability to get a woman pregnant due to fewer or less effective sperm

It is important to be open and honest with your spouse or partner about your feelings and concerns, and how you prefer to be intimate while you are having radiation therapy. Some things to keep in mind:

  • If you don’t feel like having sex, then explore other ways to be close, such as hugging, cuddling and talking.
  • Radiation therapy to the pelvis can cause permanent infertility. If you plan to have children talk to your doctor.
  • If you want to have sex, and your medical team has let you know it is okay, then go ahead. Using a water-based lubricant may be helpful. Use birth control throughout radiation treatment.
  • For women, your doctor may encourage you to use a vaginal dilator to decrease narrowing of the vagina.

Fox Chase Cancer Center offers a Women’s Menopausal and Sexual Health Program and Men’s Sexual Health Program and Erectile Dysfunction Clinic to support patients as they adjust to changes during and after cancer treatment. For more information about these programs, please call 888-369-2427.

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