context: Radiation therapy treats cancer by using high-energy waves to kill tumor cells. The goal is to destroy or damage the cancer without hurting too many healthy cells. This treatment can cause side effects, but they're different for everyone. The ones you have depend on the type of radiation you get, how much you get, the part of your body that gets treatment, and how healthy you are overall. There's no way to predict how radiation will affect you. You may have few or only mild side effects from your treatment; someone else may have a lot of problems or very severe ones. When you get radiation therapy, you'll work with a doctor who specializes in this type of medicine. It's important to talk with her about how the treatment might make you feel and what you can do to feel better. If the therapy makes you uncomfortable, speak up. If you keep your health team informed, they can help you get through treatment. There are two kinds of radiation side effects: early and late. Early side effects, such as nausea and fatigue, usually don't last long. They may start during or right after treatment and last for several weeks after it ends, but then they get better. Late side effects, such as lung or heart problems, may take years to show up and are often permanent when they do. The most common early side effects are fatigue and skin problems. You might get others, such as hair loss and nausea, depending on where you get radiation. The fatigue you feel from cancer and radiation therapy is different from other times you may have felt tired. It's an exhaustion that doesn't get better with rest and can keep you from doing the things you normally do, like going to work or spending time with family and friends. It also can seem different from day to day, which makes it hard to plan around it. It can even change how well you're able to follow your cancer treatment plan. Let your doctor know if you're struggling with fatigue. She might be able to help. There are also things you can do to feel better: Take care of your health. Be sure you're taking your medications the way you're supposed to. Get plenty of rest, be as active as you can, and eat the right foods. Work with a counselor or take a class at your cancer treatment center to learn ways to conserve energy, reduce stress, and keep yourself from focusing on the fatigue. Save your energy for the activities that are most important to you. Tackle them first when you're feeling up to it. Keep a balance between rest and activities. Too much bed rest can make you more tired. But don't over-schedule your days without giving yourself breaks. Ask for help from family and friends. If fatigue is interfering with your job, talk with your boss or HR department and ask about taking some time off from work or making adjustments in your schedule. Keep in mind that the fatigue from radiation therapy will probably go away within a few weeks after your treatment ends. The way external radiation therapy affects your skin is similar to what happens when you spend time in the sun. It may look red, sunburned, or tanned. It may also get swollen or blistered. Your skin may also become dry, flaky, or itchy. Or it may start to peel. Be gentle with your skin: Don't wear tight clothing over the area that's being treated. Don't scrub or rub your skin. To clean it, use a mild soap and let lukewarm water run over it. Avoid putting anything hot or cold on the area unless the doctor tells you to. Ask your doctor before you use any type of ointment, oil, lotion, or powder on your skin. Ask about using corn starch to help relieve itching. Stay out of the sun as much as possible. Cover the area getting radiation with clothing or hats to protect it. Ask the doctor about using sunscreen if you must be outdoors. If you're having radiation therapy for breast cancer, try not to wear a bra. If that isn't possible, wear a soft, cotton one without underwire. Don't use any tape, gauze, or bandages on your skin unless the doctor tells you to. Your skin should start to feel better a few weeks after therapy ends. But when it heals, it may be a darker color. And you'll still need to protect yourself from the sun even after radiation therapy has ended. Only people who get radiation to the scalp or the brain may have hair loss. Others won't. If it does happen, it's usually sudden and comes out in clumps. In most cases, your hair will grow back after therapy stops, but it may be thinner or have a different texture. Some people choose to cut their hair short before treatment begins to make less weight on the hair shaft. If you lose hair on top of your head, be sure to wear a hat or a scarf to protect your scalp from the sun when you go outside. If you decide to buy a wig, ask the doctor to write a prescription for one and check to see if it's covered by your insurance or is a tax-deductible expense. Other early side effects you might have usually depend on where you get the radiation. Eating Problems Radiation therapy to the head, neck, or parts of the digestive system can make you lose your appetite. But it's important to keep eating a healthy diet while you're having treatment to keep your body strong. Try eating five or six small meals spread out through the day instead of three large ones. Try new recipes or foods. Keep healthy snacks on hand. It will help you eat when you're hungry rather than waiting for mealtimes and maybe losing your appetite. Mouth Problems Before you start radiation to your head or neck, see your dentist for a thorough exam. Radiation can cause problems in your mouth that include: Mouth sores (little cuts or ulcers) Lack of saliva Thick saliva Trouble swallowing Jaw stiffness Tell your cancer team about any of these problems so they can help you feel better. To help manage these side effects: Avoid spicy and acidic foods. Don't smoke, chew tobacco, or drink alcohol. Brush your teeth often with fluoride toothpaste and a soft brush. Hearing Problems Radiation therapy to the head can sometimes cause hearing problems. One reason might be that it hardens the wax in your ears. Let your doctor know if you have trouble hearing. Nausea Radiation to the head, neck, and any part of the digestive tract can cause nausea and vomiting. Let your doctor know if that happens. She can give you medicine to control it. Also, you might be able to learn relaxation techniques and biofeedback to help control and reduce feelings of nausea. Diarrhea Radiation therapy to your belly can cause diarrhea, which typically starts a few weeks after therapy begins. The doctor will likely prescribe medications to help control it. She'll also suggest changes in your diet, such as eating small meals more often, avoiding high-fiber foods, and getting enough potassium. Fertility and Sexual Issues Radiation therapy to your pelvis can affect your sex drive and whether you'll be able to have a child. If you want to start a family or have more children, it's important to talk to your doctor about how the treatment will affect your fertility before treatment begins. Women shouldn't try to get pregnant during radiation therapy because it can hurt the baby. It also can stop periods and cause other symptoms of menopause. For men, radiation to the testes can affect sperm count and how well they work. This doesn't necessarily mean you can't father a child. But if you want to have kids later on, you should talk with your doctor to see if you should use a sperm bank before treatment begins. Treatment to the pelvis can make sex painful for some women and can also cause scarring that makes the vagina less able to stretch. In men, radiation can affect the nerves and blood vessels that control erections. Your doctor can help you understand what might happen and how you can handle it. It's natural to have less interest in sex when you're having treatment for cancer. But your sex drive will usually come back after treatment stops. Talk openly with your partner about how you can stay close. Make sure you listen to their concerns, too. Late side effects from radiation therapy take months and sometimes years to show up and usually don't go away. But not everyone will have them. These problems happen when radiation damages your body. For example, scar tissue can affect the way your lungs or your heart works. Bladder, bowel, fertility, and sexual problems can start after radiation to your belly or pelvis. Another possible late effect is a second cancer. Doctors have known for a long time that radiation can cause cancer. And research has shown that radiation treatment for one cancer can raise the risk for developing a different cancer later. Factors that can affect that risk include the amount of radiation used and the area that was treated. Talk with your doctor about the potential risk and how it compares to the benefits you'll get from radiation therapy.