What Is Cancer? Cancer happens when cells divide and multiply much faster than most normal cells. Uncontrolled cell growth can lead to masses of cancer cells called tumors, or to a situation where healthy cells are crowded out and can no longer do their jobs efficiently. What Are Side Effects? Chemotherapy (or "chemo") and radiation therapy are the two most common types of cancer treatment. They work by destroying these fast-growing cells. But other types of fast-growing healthy cells (such as blood and hair cells) also can be damaged along with cancer cells, causing adverse reactions, or side effects. Side effects can range from tiredness and flu-like symptoms to hair loss and blood clotting problems. Because it's hard for doctors to predict how the body will react, a child who is being treated for cancer is closely monitored. Doctors weigh the amount and severity of side effects against the benefits of treatments. Fortunately, most side effects are temporary. As the body's normal cells recover, these problems start to go away. Side effects vary: Some can be merely unpleasant, while others can be much more serious. Some show up right away, while others develop over time. Some kids have just a few, while others have many over the course of treatment. What Are Common Side Effects of Chemo and Radiation? Chemo and radiation cause similar side effects. Chemo's side effects depend on the type of drug used, the dosage, and a child's overall health. These effects are more likely to affect the whole body. Radiation's side effects, on the other hand, tend to affect the area being treated. But they do still depend on the dose of radiation given, the location on the body, and whether the radiation was internal or external. Here are some of the side effects associated with these cancer treatments, and how to manage them: Fatigue Tiredness (fatigue) is the most common side effect of both chemotherapy and radiation. Even the most active kids are likely to find themselves exhausted and perhaps even a little "foggy-headed" during treatment — and possibly for a while afterward. This is normal. Encourage your child to scale back on activities and to rest as much as possible. When treatment is over, your child's energy should return. Flu-like Symptoms Some cancer medicines appear to trigger the body's normal inflammatory response, producing flu- or cold-like symptoms, such as a runny nose, chills, and cough. Drinking plenty of fluids can help clear excess mucus. Also ask your doctor which, if any, over-the-counter medicines might help. Pain Some chemo drugs cause headaches, muscle pains, stomach pains, or even temporary nerve damage, which can result in burning, numbness, or tingling in the hands and feet. If this happens, your doctor can prescribe medicines that can help. Never use over-the-counter or herbal medicines without your doctor's OK, though, as these can interact with the chemo drugs. Mouth, Gum, and Throat Sores Both chemo and radiation (specifically to the head and neck) can lead to mouth sores, sensitive gums, an irritated throat, and an increased risk of tooth decay. The doctor may prescribe a mouth rinse to reduce irritation. Soft, cool foods might be easier to eat, and high-acid foods and juices (like oranges or tomatoes) should be avoided. Regular dental checkups are important too. Gastrointestinal Problems Many types of chemo drugs are known to cause nausea, vomiting, loss of appetite, constipation, or diarrhea. Medicines can prevent or ease a lot of these symptoms. It's also common for kids to find that their taste preferences change while on chemo (they can't tolerate certain smells or textures, for example). If your child's appetite wanes, try offering several small servings of something rather than three large meals. Also concentrate on keeping your child hydrated with water, juices, and broths. Gastrointestinal symptoms related to radiation tend not to be as severe as those from by chemo, except in children who get radiation to the pelvis or abdomen. Skin Changes Chemo drugs commonly cause rashes, redness, and other types of skin irritation — especially if your child had radiation before the chemo (this is called "radiation recall"). Radiation alone can cause similar symptoms, along with blisters, peeling, and swelling, in the area of treatment. Wearing loose, soft cotton clothing may help with the discomfort. Your doctor might also recommend or prescribe creams or ointments. Because the affected area can be more sensitive to the sun for a while after treatment, your child should always wear sunscreen with an SPF of at least 30 whenever going outdoors. Weight Changes Some kids have weight loss or weight gain. It's common for those taking steroids to have an increased appetite and gain weight in unusual places, like the cheeks or back of the neck. Other kids might have decreased appetites or trouble keeping food down (especially if they're feeling nauseated after chemo). If you're concerned about your child's weight, talk to the doctor about helping your child maintain a healthy weight based on his or her medical needs. Hair Loss During chemo, hair thinning and hair loss may happen all over the body. Radiation therapy to the head and neck may cause hair loss in that area. But radiation anywhere else will not cause the hair on the head to fall out. Though some kids take hair loss in stride, others find it upsetting. Tell your child that the hair will grow back — though it might be a slightly different color or texture. In the meantime, many kids choose to wear baseball hats, bandanas, scarves, or wigs. Before treatment, some kids get shorter haircuts, as it can be easier to watch shorter strands of hair fall rather than long ones. Kidney and Bladder Problems Some chemo drugs affect the kidneys. Frequent blood tests will check kidney function. Staying well hydrated can help. Tell the doctor if your child has blood in the pee or any problems urinating. Anemia Chemotherapy drugs and radiation can destroy all types of healthy blood cells and harm the body's production of new ones. Low levels of red blood cells (the cells that carry oxygen) can lead to anemia, which causes fatigue, paleness, shortness of breath, and a fast heartbeat. Frequent blood draws throughout treatment will monitor the levels of these cells. If they get too low, your child may get donor cells through a blood transfusion. Blood Clotting Problems Cells that help blood to clot, called platelets, are another type of blood cell that can be affected during cancer treatment, especially chemo. Low platelets, or thrombocytopenia, can lead to bleeding. This may cause small red spots on the skin, bloody or black bowel movements or vomit, or bleeding from the nose, gums, or line site (the area where fluids and medicines are given to people with cancer). Kids with a low platelet count have to take it easy to reduce the risk of bleeding. That means avoiding rough play and contact sports (like football), and brushing with a soft toothbrush and flossing very gently. In very serious cases of thrombocytopenia, a child might need a blood transfusion. Neutropenia White blood cells (WBCs) also can be depleted during or after cancer treatment. WBCs called neutrophils help fight infection. Having too few can put a child at increased risk of serious infection, a condition called neutropenia. A fever can be a sign of serious infection, so tell your doctor right away if your child gets one. Kids with neutropenia need to take special precautions against germs. Like all kids, they should wash their hands well and often, especially before eating, after using the bathroom, and after touching animals. They also need to avoid crowded indoor places or visiting with friends or family members who have contagious illnesses (such as a cold, the flu, or chickenpox). People who have recently received live-virus vaccines, such as measles or oral polio, can pass these viruses to kids with low blood cell counts, so it's also important to avoid contact with them. To prevent food-borne infection, kids with neutropenia shouldn't eat raw seafood, undercooked meat, or eggs. Infection Because their immune systems are compromised, kids with cancer (especially those with neutropenia) can't fight off bacteria and other germs that enter the body. So a seasonal virus or a cold can quickly turn into a life-threatening infection. Signs of infection include fever or chills, coughing or congestion, vomiting or diarrhea, and pain (perhaps in the ears, throat, belly, or head, or pain when going to the bathroom). Or there might be redness, swelling, pain, or oozing around the line site. If your child has any of these symptoms, especially a fever, contact your doctor right away. How Long Do Side Effects Last? Most side effects start to go away after cancer treatment ends and the healthy cells have a chance to grow again. How long this takes typically on a child's overall health and the types and amounts of drugs and/or radiation he or she had. Sometimes, though, cancer treatment can cause lasting changes to a growing body. These long-term side effects (called late effects) can include damage to the heart, lungs, brain, nerves, kidneys, thyroid gland, or reproductive organs. In some cases, kids and teens who've had some types of chemotherapy have a higher risk of developing a second type of cancer later in life. Before treatment, the doctor will talk to you about your child's risk of late effects and what precautions can be taken before treatment, if any. For example, some teens who undergo treatments with fertility risks can take preventive measures like egg or sperm preservation. What Else Should I Know? Cancer treatment has come a long way. But it can be hard for kids and teens to cope with the sometimes painful or uncomfortable side effects of treatment. Fortunately, doctors have many ways to make treatments easier to manage. Your child also might feel the emotional effects of having a serious illness. Answer questions and help explain what's going on in an age-appropriate way. You also can talk with the care team. A hospital support group, life specialist, social worker, or psychologist from the care team can help your child and your whole family before, during, and after cancer treatment. Back to Articles Related Articles Cancer Center Visit our Cancer Center for teens to get information and advice on treating and coping with cancer. Read More Cancer Center From treatments and prevention to coping with the emotional aspects of cancer, the Cancer Center provides comprehensive information that parents need. Read More Chemotherapy Chemotherapy (chemo) is treatment with medicines that stop the growth of cancer cells. Find out how chemo works and what to expect when getting treatment. Read More Coping With Cosmetic Effects of Cancer Treatment It's normal for kids to have hair loss, skin changes, or weight gain during treatment. This article offers tips for helping kids feel better about their appearance. Read More Side Effects of Chemotherapy and Radiation Side effects of cancer treatment can include flu-like symptoms, hair loss, and blood clotting problems. After treatment ends, most side effects go away. Read More Late Effects of Cancer and Cancer Treatment Long-term side effects, or late effects, happen to many cancer survivors. With early diagnosis and proper follow-up care, most late effects can be treated or cured. Read More Radiation Therapy More than half of all people with cancer are treated with radiation therapy. Get the facts on radiation therapy, including what it is, what to expect, and how to cope with side effects. Read More Cancer Center Cancer is a serious illness that needs special treatment. Find out more about how kids can cope with cancer. Read More Chemotherapy Chemotherapy (chemo) is treatment with medicines that stop the growth of cancer cells. Read More Word! Chemotherapy Chemotherapy is the use of special medicines to treat cancer. Read More Effects of Cancer Treatment on Fertility While some cancer treatments have little to no effect on reproductive health, others are more likely cause temporary or permanent infertility. Read More Chemotherapy Chemotherapy is a big word for treatment with medicines used to help people who have cancer. This medicine kills the cancer cells that are making the person sick. Read More Radiation Therapy Radiation therapy, also called radiotherapy, irradiation, or X-ray therapy, is one of the most common forms of cancer treatment. Read More Neutropenia Certain cancers, or cancer treatment, can weaken the immune system, requiring a child to stay home to avoid exposure to germs. Here are ways to help your child make the best of it. Read More Caring for Siblings of Seriously Ill Children By being aware of what healthy siblings are going through and taking a few steps to make things a little easier for them, parents can help kids cope. Read More Caring for a Seriously Ill Child Taking care of a chronically ill child is one of the most draining and difficult tasks a parent can face. But support groups, social workers, and family friends often can help. 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