February 22, 2024/Cancer Care & Prevention

Does Breast Cancer Treatment Make You Tired?

The answer is yes — but there are things you can do to help boost your energy

Female asleep on couch on backyard deck next to laptop and glasses

Breast cancer treatment can be exhausting.


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That statement probably doesn’t surprise you. Nobody expects breast cancer to be easy, after all. But even if you go into treatment thinking it will be draining, the grueling reality of it can still be startling.

By some estimates, more than 90% of people with cancer experience fatigue during treatment. This isn’t just feeling tired. It’s about reaching a level of weariness that can make getting out of bed challenging.

So, what should you do if you have breast cancer and don’t feel like doing much of anything? Let’s talk it through with oncologist Tiffany Onger, MD.

Breast cancer and exhaustion

There isn’t one single reason why breast cancer and treatment lead to stretches of physical, emotional and mental fatigue. “It really can be due to any number of different causes,” explains Dr. Onger.

The list includes:

  • The disease itself. Breast cancer can knock your hormone levels out of balance; damage tissues and cells; and cause anemia by depleting healthy red blood cells — all of which can sap energy levels. (There’s more, too, but you get the idea.)
  • Cancer treatments. Chemotherapy, radiation therapy and breast cancer surgery all place extra stress on your body that can cause extra tiredness as you work through the recovery process.
  • Mental health. Worrying takes a lot out of you … and who doesn’t worry following a breast cancer diagnosis? Mood changes or a turn toward depression can deepen low-energy feelings as well.
  • Pain. Research shows that elevated levels of cancer-related pain increase fatigue. And the worse the pain, the higher the level of tiredness.
  • Lack of nutrition. Food is energy. If you’re not eating much because of nausea from cancer or the treatment, your body won’t get the nutrients it needs to power through your day.
  • Medications. Side effects of medication prescribed as part of your cancer care may include general fatigue.
  • Lack of sleep. Insomnia is often a side effect of breast cancer and its treatment. Restless nights without much sleep won’t allow you to recharge your body battery.

“Fatigue is hard to quantify and there isn’t a test that offers measurable data points,” notes Dr. Onger. “But it’s real and it can be a formidable challenge.”

How long can cancer-related tiredness last?

Every person is different, so there’s no set timetable for when cancer-related fatigue lifts. It might last only a few days or weeks, says Dr. Onger. It also could extend for months or even years.

“One of the most important things I talk to my patients about is knowing that fatigue can happen,” she continues. “It’s natural to feel fatigued as your body works to heal. Give yourself some grace during this time.”


And know that eventually, it will get better.

Signs of breast cancer fatigue

When cancer fatigue hits during the day, it may arrive with the following feelings or symptoms (aside from overall tiredness and lack of energy):

  • An inability to focus or concentrate.
  • Lack of motivation.
  • Irritability.
  • Nervousness.
  • Impatience.

How to overcome cancer fatigue

So, what can you do to build energy and break through that cancer-related wall of fatigue? Let’s build a management plan to tackle your tiredness.

Keep a fatigue diary

Keep track of when your energy levels seem at their highest and when they bottom out. The time of day or activities you were doing at those times may offer clues as to what you can do to improve your day-to-day routine.


As odd as it may sound, the solution to being less tired often starts with moving more.

“Exercise may feel like the last thing that you want to do — but it may be the most necessary,” emphasizes Dr. Onger. “Moving around helps to give your body the strength and energy it needs.”

That’s because exercise brings more oxygen to your muscles, which helps your body move and function better. Movement also causes your system to release energy-building hormones that offer an extra jolt.

Look to move your body in gentle ways: “Walk or stretch for five minutes … seven minutes … 10 minutes — whatever you can do,” encourages Dr. Onger. “Keep building a routine, day by day, and focus on getting stronger.”


Ideal activities include:

  • Walking. Taking a simple stroll around your neighborhood can provide both physical and emotional benefits. “Don’t underestimate the value of getting out for some sunlight and fresh air,” says Dr. Onger.
  • Yoga. Stretching and moving your body through various yoga poses can build strength and release stress. Even yoga movements done in a chair reinforce the activity’s therapeutic mind-body-breathe connection.
  • Resistance training. Research shows that people with breast cancer better tolerate treatment if they exercise using hand-held weights, resistance bands or even their body weight.
  • Whatever gives you joy. What’ll get you moving with a smile? Maybe it’s cycling, swimming or gardening. Just find something you enjoy and do it regularly.

Eat healthy

Make sure that you’re consuming enough calories, as well as the right sort of calories. A balanced diet loaded with fruits, vegetables, whole grains and lean proteins can help keep your energy levels high. It’s important to stay hydrated, too.

(Learn more about the best foods to eat if you have breast cancer.)

Get enough sleep

Creating a consistent bedtime routine and sleep schedule may help you get the restorative ZZZs your body needs. Try to limit daytime naps to an hour or less, so you’re ready for bed at night.

The bottom line?

Talk to your healthcare provider if you can’t shake that feeling of exhaustion during your breast cancer recovery. They may suggest options like treatment adjustments, lifestyle changes or counseling to address the issue.

“What we want to avoid is someone lying in bed for 18 hours a day,” says Dr. Onger. “That’s not going to help you reach your treatment goal.”

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