Breast Cancer Treatment Side Effects

All cancer treatments can cause side effects. It’s important that you report any side effects that you experience to your healthcare team so they can help you manage them. Report them right away—don’t wait for your next appointment. Doing so will improve your quality of life and allow you to stick with your treatment plan. It’s important to remember that not all patients experience all side effects, and patients may experience side effects not listed here.

There are certain side effects that may occur across different treatment approaches. Following are tips and guidance for managing these side effects.

Digestive tract symptoms

Nausea and vomiting

  • Avoid food with strong odors, as well as overly sweet, greasy, fried, or highly seasoned food
  • Eat meals cold or at room temperature, which often makes food more easily tolerated
  • Nibble on dry crackers or toast. These bland foods are easy on the stomach
  • Having something in your stomach when you take medication may help ease nausea


  • Drink plenty of water. Ask your doctor about using drinks such as Gatorade which provide electrolytes as well as liquid. Electrolytes are body salts that must stay in balance for cells to work properly
  • Over-the-counter medicines such as loperamide (Imodium A-D and others) and prescription drugs are available for diarrhea but should be used only if necessary. If the diarrhea is bad enough that you need medicine, discuss it with your doctor or nurse
  • Choose foods that contain soluble fiber—for example beans, oat cereals, oranges, and flaxseeds. High-pectin foods such as peaches, apples, oranges, grapefruit, bananas, and apricots can also help to avoid diarrhea
  • Avoid food high in refined sugar and those sweetened with sugar alcohols such as sorbitol and mannitol. Look for this low-calorie sweetener on food labels; the names of this type of sweetener usually end with the letters “ol”
  • Low fat food choices are less likely to cause diarrhea than fatty, greasy, or fried foods. The fats you eat should come from healthy sources, such as olive oil, canola oil, avocado, olives, nuts, and seeds
  • Limit or avoid lactose, especially if you are lactose-intolerant. There are plant-based milk alternatives you can try, such as soy or rice milk. If lactose is an essential part of your diet, there are dairy products with added lactase (which breaks down lactose) and dietary lactase supplements

Loss of appetite

  • To help maintain your weight, eat small meals throughout the day. That’s an easy way to take in more protein and calories. Try to include protein in every meal
  • To keep from feeling full early, avoid liquids with meals or take only small sips (unless you need liquids to help swallow). Drink most of your liquids between meals
  • Be as physically active as you can. Sometimes, taking a short walk an hour or so before meals can help you feel hungry
  • Keep high-calorie, high-protein snacks on hand such as hard-boiled eggs, peanut butter, cheese, ice cream, granola bars, liquid nutritional supplements, puddings, nuts, canned tuna, or trail mix
  • Eat your favorite foods any time of the day. For example, if you like breakfast foods, eat them for dinner
  • If you are struggling to maintain your appetite, talk to your health care team about whether appetite-building medication could be right for you


Fatigue (extreme tiredness not helped by sleep) is one of the most common side effects of many cancer treatments. If you are taking a medication, your doctor may lower the dose of the drug, as long as it does not make the treatment less effective. If you are experiencing fatigue, talk to your doctor about whether taking a smaller dose is right for you.

There are a number of other tips for reducing fatigue:

  • Take several short naps or breaks
  • Take short walks or do some light exercise, if possible
  • Try easier or shorter versions of the activities you enjoy
  • Ask your family or friends to help you with tasks you find difficult or tiring
  • Save your energy for things you find most important

Fatigue can be a symptom of other illnesses, such as anemia, diabetes, thyroid problems, heart disease, rheumatoid arthritis, and depression. So be sure to ask your doctor if he or she thinks any of these conditions may be contributing to your fatigue.

Also, it could be very valuable to talk to an oncology social worker or oncology nurse. These professionals can also help you manage fatigue. They can work with you to manage any emotional or practical concerns that may be causing symptoms and help you find ways to cope.


To help your doctor prescribe the best medication, it’s useful to give an accurate report of your pain. Keep a journal that includes information on:

  • Where the pain occurs
  • When the pain occurs
  • How long it lasts
  • How strong it is on a scale of 1 to 10, with 1 being the least amount of pain and 10 the most intense
  • What makes the pain feel better and what makes it feel more intense

There are a number of options for pain relief, including prescription and over-the-counter medications. It’s important to talk to a member of your healthcare team before taking any over-the-counter medication, to determine if they are safe and will not interfere with your treatments. Many pain medications can lead to constipation, which may make your pain worse. Your doctor can prescribe medications that help to avoid constipation.

Physical therapy, acupuncture, and massage may also be of help in managing your pain. Consult with a member of your healthcare team before beginning any of these activities.

Bone loss

Both hormone therapies and chemotherapy can cause bone loss, which increases a woman’s risk for osteoporosis (a condition in which bones become weak and brittle, leading to a higher risk of fracture). Talk with your healthcare team about how exercise and changes in your diet may help keep your bones healthy. It’s also important to talk to your doctor about the medications available for bone health:

  • Bisphosphonates such as zoledronic acid (Zometa and others) slow the process by which bone wears away and breaks down. These medications belong to a class of drugs called osteoclast inhibitors
  • RANK ligand inhibitors block a factor in bone development known as RANK ligand, which stimulates cells that break bone down. By blocking RANK ligand, these drugs increase bone density and strength. So far, the only drug approved in this class is denosumab (Xgeva, Prolia). Like bisphosphonates, RANK ligand inhibitors are a type of osteoclast inhibitor.

Hot flashes

Breast cancer treatments can lead to menopausal symptoms, such as hot flashes and night sweats. If you are experiencing these side effects, speak with your health care team about ways to cope with them. The following tips may also help:

  • Identify the triggers for your hot flashes. For many women, hot flashes can be triggered by stress, a hot shower, caffeine, or spicy foods.
  • Change your lifestyle habits to cope with the triggers. That may mean regular exercise, using relaxation techniques, and/or changing your diet.
  • Dress in layers and keep ice water handy to cool yourself off.
  • Avoid synthetic materials, especially at nighttime; wear pajamas and use sheets made of cotton instead.
  • Take a cool shower before going to bed
  • Try a mild medication such as acetaminophen (Tylenol and others)


Women with breast cancer who have undergone lymph node removal and/or radiation as part of their treatment are at risk for developing lymphedema, a condition in which the body’s lymphatic fluid is unable to circulate properly. The lymphatic fluid builds up in soft tissues (usually in an arm or a leg), causing painful swelling. In addition to swelling of the affected limb, the most common problems associated with lymphedema are pain, hardening of the skin, and loss of mobility.

Here are some things you can do to ease the discomfort of lymphedema:

  • Get help for your symptoms as soon as possible. Contact your health care team at the first sign of lymphedema symptoms. If left untreated, the swelling can get worse and may cause permanent damage
  • Consider undergoing manual lymph drainage (MLD). This type of massage helps move the fluid from where it has settled. Afterward, the affected limb is wrapped in low-stretch bandages that are padded with foam or gauze
  • Learn exercises that can help prevent swelling due to fluid build-up. Your healthcare team can refer you to a program of special lymphedema exercises, taught and monitored by a physical therapist
  • Wear a compression sleeve. This can help drain the lymphatic fluid. It’s important to always wear a compression garment when flying, even on short flights.
  • Be kind to your body. Carrying heavy packages, luggage, or shoulder bags puts stress on your affected limb and could cause additional swelling and pain.

Vaginal dryness

Treatments for breast cancer can lead to vaginal dryness and a lowered sex drive. Use of a personal lubricant (such as Astroglide) and/or a moisturizer (such as Replens) can often help. It’s important to keep an open dialogue with your intimate partner. Vaginal dryness can make sexual intercourse uncomfortable, but together you can find other ways to please each other.

If vaginal dryness persists, talk to your doctor about whether prescription medicines designed to treat the condition are right for you, such as hormone creams or suppositories (medicines inserted into the vagina). Your healthcare team can also advise you on regaining the desire for sex. You may wish to ask for a referral to a healthcare professional who specializes in these issues.

Treatment-specific side effects


The side effects specific to chemotherapy depend on the type and dose of drugs given and the length of time they are used, and can include the following:

Hair loss. Hair loss is often one of the more frustrating aspects of chemotherapy. When hair falls out, it can affect a woman’s self-image and quality of life. Depending on the treatment, hair loss may start anywhere from one to three weeks after the first chemotherapy session. Hair usually starts to grow back after the end of treatment. It may have a different texture or color, but these changes are usually temporary. Many women who lose their hair during chemotherapy treatments choose to wear a head covering, whether it’s a scarf, turban, hat, or wig. Some insurance plans may cover part of the cost of these head coverings. If you choose to wear a wig, consider buying one before you lose much hair so that you feel more prepared, and so that you will have a good match to your own hair color. You can have your wig professionally fitted and styled by a full-service wig salon; look for a salon in your community that specializes in hair loss resulting from chemotherapy.

Nerve damage. Some women on chemotherapy or targeted treatments experience nerve damage; the symptoms may include difficulty picking up objects or buttoning clothing, problems maintaining your balance, difficulty walking, and hearing loss. Peripheral neuropathy is a form of nerve damage that may cause numbness or tingling in the hands and feet. Often, nerve damage due to cancer treatments is temporary; it will usually get better, but it can take time. If you are coping with this side effect, take extra care when handling hot, sharp, or dangerous objects. Also, use handrails on stairs and in the tub or shower.

Low white blood cell counts. Chemotherapy may lead to low white blood cell counts, a condition called neutropenia. White blood cells play a key role in fighting infections, and a reduced number of these cells increases the risk of infection. Your doctor can prescribe medication designed to help increase white blood cell counts. If you develop a fever, which is a sign of infection, let your health care team know immediately so that you can get proper treatment.

Memory lapses. After chemotherapy, some people have difficulty concentrating or thinking clearly. If you experience any of these symptoms, speak with your health care team. There are a number of things you can do to help you cope, including:

  • Keep a diary or a log to track how your memory lapses affect your daily routine.
  • Make lists. Carry a pad, smart phone, or tablet with you and note the things you need to do.
  • Organize your environment. Keep things in familiar places so you’ll remember where you put them. To help stay focused, you should work, read and do your thinking in an uncluttered, peaceful environment
  • Repeat information you’re given aloud. This can help give your memory an extra boost
  • Keep your mind active. Do crossword puzzles and word games, or go to a lecture on a subject that interests you
  • Exercise, eat well, and get plenty of rest and sleep. This helps to keep your memory working at its best

Mouth sores (mucositis) are also a side effect of chemotherapy. Your doctor may recommend treatments such as:

  • Coating agents. These medications coat the entire lining of your mouth, forming a film to protect the sores and minimize pain
  • Topical painkillers. These are medications that can be applied directly to your mouth sores
  • Over-the-counter treatments. These include rinsing with baking soda or salt water, or “magic mouthwash,” a term given to a solution to treat mouth sores. Magic mouthwash usually contains at least three of these ingredients: an antibiotic, an antihistamine or local anesthetic, an antifungal, a corticosteroid, and/or an antacid

Chemotherapy can also cause changes in the way food and liquids taste, including causing an unpleasant metallic taste in the mouth. Many people find that switching to plastic utensils helps. It may also help to avoid eating or drinking anything that comes in a can, and to use enamel-coated pots and pans for food preparation.

Radiation therapy

Changes to the skin are the most common side effects of radiation therapy; those changes can include dryness, swelling, peeling, redness, and blistering. If a reaction occurs, contact your healthcare team so the appropriate treatment can be prescribed. It’s especially important to contact your healthcare team if there is any open skin or painful areas, as this could indicate an infection. Infections can be treated with an oral antibiotic or topical antibiotic cream.

Targeted treatments and hormone therapy

Targeted treatment drugs and hormone therapy don’t have the same effect on the body as do chemotherapy drugs, but they can still cause side effects.

Side effects of certain targeted therapies can include diarrhea, liver problems (such as hepatitis and elevated liver enzymes), problems with blood clotting and wound healing, and high blood pressure. Nerve damage, as outlined in the Chemotherapy Side Effects section above, may also occur.

The side effects of hormone therapy are dependent on the type of therapy and include hot flashes (seen more with tamoxifen) and joint pain (seen more with aromatase inhibitors).


Information provided by CancerCare.