Preparing for Radiation Therapy: 5 Common Side Effects and How to Manage Them

Facing radiation therapy can feel overwhelming, but understanding what to expect is a powerful step toward feeling more prepared and in control. This guide breaks down the five most common side effects patients experience, offering practical, oncologist-approved advice on how to manage them and navigate your treatment with confidence.

Understanding Radiation Therapy Side Effects

Before we dive into the specifics, it’s important to know that side effects from radiation are typically localized. This means they usually only affect the specific part of your body being treated. For example, a patient receiving radiation for breast cancer will not lose the hair on their head, but might experience skin changes on their chest. The severity of these effects can also depend on the dose of radiation and your overall health.

Always remember that your oncology team is your best resource. They will give you personalized advice for your situation. This guide is here to provide a general overview of what many patients can prepare for.

1. Fatigue

Fatigue is by far the most common side effect of radiation therapy, regardless of the treatment area. It’s a profound feeling of tiredness or exhaustion that isn’t relieved by rest. It can start a few weeks into treatment and may last for several weeks or even months after treatment ends.

Why it happens: Your body is working hard to repair the healthy cells that are inevitably damaged along with the cancer cells. This healing process requires a tremendous amount of energy. The stress of treatment and daily travel to appointments can also contribute.

How to Prepare and Manage:

Prioritize Rest: Listen to your body. If you feel tired, rest. This might mean taking short naps during the day. Don’t feel guilty about needing more sleep than usual.
Plan for Light Activity: It may sound counterintuitive, but gentle exercise, like a short daily walk, can actually boost your energy levels and improve your mood. Check with your doctor before starting any exercise routine.
Stay Hydrated and Eat Well: Dehydration can make fatigue worse. Drink plenty of fluids throughout the day. Focus on a balanced diet rich in protein and calories to give your body the fuel it needs to heal.
Ask for Help: Don’t be afraid to lean on your support system. Let friends and family help with errands, meals, or childcare. Conserving your energy for healing is your top priority.

2. Skin Changes

The skin in the treatment area is often affected by radiation. The reactions can range from mild redness and dryness to more significant peeling and soreness, similar to a bad sunburn. These changes usually begin a couple of weeks into treatment and heal gradually after it is complete.

Why it happens: Radiation passes through the skin to reach the tumor, and in doing so, it can damage the skin’s rapidly dividing cells.

How to Prepare and Manage:

Be Gentle with Your Skin: When you wash, use lukewarm water and a mild, unscented soap. Pat the skin dry gently with a soft towel; do not rub.
Moisturize Frequently: Your care team will likely recommend specific creams or lotions. Common suggestions include fragrance-free, hypoallergenic moisturizers like Aquaphor or Calendula cream. Apply it as directed by your nurse or doctor.
Wear Loose, Soft Clothing: Avoid tight-fitting clothes, starched collars, or rough fabrics like wool over the treated area. Cotton and other soft materials are best.
Protect Your Skin from the Sun: The treated skin will be extremely sensitive to the sun. Protect it by wearing a wide-brimmed hat or protective clothing. Use a broad-spectrum sunscreen with an SPF of 30 or higher, but always ask your doctor which one is safe to use on the treated area.

3. Hair Loss (in the Treated Area)

Many people associate cancer treatment with hair loss, but with radiation, this effect is localized. Hair loss only occurs in the specific area where the radiation beams enter and exit the body. For example, radiation to the head will cause hair loss on the scalp, while radiation to the chest or pelvis will not.

Why it happens: Radiation targets rapidly dividing cells, which includes cancer cells but also hair follicles.

How to Prepare and Manage:

Know What to Expect: Ask your doctor if your treatment area will cause hair loss. If so, it typically begins 2 to 3 weeks after your first session.
Be Gentle with Your Scalp: If you are receiving radiation to your head, use a mild shampoo, like baby shampoo, and a soft-bristle brush.
Consider Your Options: Some people choose to cut their hair short or shave their head before treatment begins to feel more in control. Others prefer to use soft hats, scarves, or wigs. The American Cancer Society has resources to help you find wigs at little to no cost.
Understand Regrowth: In many cases, the hair will grow back a few months after treatment ends. However, the new hair may have a different texture or color. With very high doses of radiation, hair loss can sometimes be permanent.

4. Nausea and Vomiting

Nausea is not as common with radiation as it is with chemotherapy, but it can occur, especially if the treatment area is near the stomach, abdomen, or brain. If it happens, it usually starts a few hours after a treatment session.

Why it happens: Radiation to the abdomen can irritate the lining of your stomach and intestines. Radiation to the brain can affect the part of the brain that controls nausea.

How to Prepare and Manage:

Eat Small, Frequent Meals: Instead of three large meals, try eating five or six smaller ones throughout the day. An empty stomach can make nausea worse.
Choose Foods Carefully: Stick to bland, easy-to-digest foods like crackers, toast, rice, and bananas. Avoid foods that are greasy, spicy, or have strong odors.
Stay Hydrated: Sip on clear liquids like water, ginger ale, or light broths throughout the day.
Talk to Your Doctor: If nausea is interfering with your ability to eat, don’t suffer in silence. Your doctor can prescribe very effective anti-nausea medications to help you feel better.

5. Mouth and Throat Problems

If you are receiving radiation to the head, neck, or chest area, you may experience side effects like mouth sores, a dry mouth, or difficulty swallowing. These can be uncomfortable and make eating difficult.

Why it happens: Radiation can damage the salivary glands and the sensitive lining of the mouth and throat.

How to Prepare and Manage:

Practice Excellent Oral Hygiene: Brush your teeth and gums gently with a soft-bristle toothbrush and fluoride toothpaste after every meal.
Use a Soothing Rinse: Avoid commercial mouthwashes that contain alcohol. Instead, your doctor may recommend a simple rinse made of 1 quart of water, 1 teaspoon of salt, and 1 teaspoon of baking soda. Swish and spit several times a day.
Keep Your Mouth Moist: Sip water frequently, suck on ice chips, or use a saliva substitute spray to combat dryness.
Choose Soft, Moist Foods: Eat foods that are easy to swallow, such as soups, yogurt, scrambled eggs, and smoothies. Avoid crunchy, salty, or acidic foods that can irritate your mouth.

Frequently Asked Questions

When do radiation side effects typically start? Most side effects begin to appear in the second or third week of treatment. They are cumulative, meaning they may become more noticeable as you go through more sessions. Most will resolve within a few weeks after your final treatment.

Are the side effects of radiation permanent? Most acute side effects, like skin redness and fatigue, are temporary and go away after treatment ends. However, some long-term side effects can occur months or years later. Your radiation oncologist will discuss any potential long-term risks with you based on your specific treatment plan.

Is there anything I can do before treatment to minimize side effects? Yes. Quitting smoking is one of the most important things you can do, as smoking can make side effects worse and treatment less effective. Eating a healthy, balanced diet and staying hydrated before you start can also help your body tolerate treatment better. Always discuss your health and any supplements you are taking with your doctor beforehand.