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Cancer Fatigue: What You Should Know

cancer fatigue

It’s normal to feel tired after we’ve had cancer. In fact, cancer-related fatigue is the most common side effect. More than 80 percent of people experience fatigue at some point during their journey. Even so, we don’t all experience it the same way.

Here’s what you should know about cancer-related fatigue, how it’s diagnosed, and how you can overcome the lack of energy to improve your quality of life.

What is cancer-related fatigue?

Understanding cancer-related fatigue means grasping the difference between tiredness and exhaustion. It’s common to feel tired, especially during cancer treatment. The primary difference between tiredness and fatigue is that tiredness can be overcome with a good night’s sleep. Fatigue, however, results in overwhelming exhaustion that has a debilitating impact on our daily lives. 

Cancer fatigue symptoms can feel like:

  • A feeling of heaviness, exhaustion, or a lack of motivation
  • Irritability or sadness
  • Difficulty concentrating or focusing
  • A sense that you just can’t get your energy back

Cancer-related fatigue has a negative impact our quality of life. There are different levels of cancer-related fatigue, ranging from acute to chronic. Some people feel fatigue during treatment which diminishes afterward. However, it’s also common to find fatigue in cancer survivors well after treatment has ended. 

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What causes cancer fatigue?

Cancer treatments cause changes to our bodies that lead to fatigue. Radiation therapy, chemotherapy, immunotherapy, etc., all take a toll on the body. The type of treatment may impact the level of fatigue you experience.

For example, people with cancer who go through chemotherapy tend to experience severe fatigue in the days after treatment. Conversely, radiation therapy has a cumulative effect resulting in persistent fatigue that intensifies as time goes by.

Treatment side effects on fatigue levels

Health professionals haven’t identified a single cause of fatigue in patients undergoing treatment. Cancer-related fatigue is linked to many different things happening within the body, like:

  • A low red blood cell count (chemotherapy-induced anemia)
  • Side effects of our treatments and medications
  • Post-surgery healing
  • Hormone changes
  • Blood transfusion side effects
  • Damage to normal cells during treatment
  • Changes in blood pressure 

Lifestyle impacts on fatigue levels

In addition to the negative effects of fatigue during cancer treatment, some of our lifestyle habits also impact fatigue in people. For example:

  • A poor diet
  • Diminished nutrition related to cancer treatments (i.e., not being able to eat due to illness)
  • Not enough sleep or poor-quality sleep
  • Too much rest or extended periods of inactivity
  • Too many daily activities (i.e., trying to do everything you did before)
  • Poor stress management

Fatigue may also stem from the emotions we’re dealing with, like stress, anxiety, and depression. Even healthy people experience symptoms of fatigue in relation to mental health.

It’s normal to have a wide range of emotions surrounding diagnosis and treatment. When we’re already tired from what cancer is doing to our body, it’s an even bigger drain on our energy.

How cancer fatigue is diagnosed

If you notice the signs of cancer-related fatigue, talk to your cancer care team. You’ll go through a few evaluations to assess your levels of fatigue and any underlying causes. Your health care team will often have patients with fatigue keep a journal to identify patterns. For example, if the fatigue occurs at a certain time of day or after you exude more physical energy doing activities.

Additionally, you may undergo some blood tests to determine if there’s an underlying medical condition impacting your energy levels. As mentioned before, one of the effects of cancer and treatment is changes in hormones or iron levels. Blood tests will identify if you’re experiencing hypothyroidism, an electrolyte imbalance, or chemotherapy-induced anemia. 

Once your cancer care team has the relevant data, they can work with you to create a management plan.

Why it’s important to treat cancer-related fatigue

The management of fatigue isn’t just important for feeling better and living life. Cancer fatigue can be extremely debilitating. It can affect so many areas of our lives and our healing journey.

Cancer-related fatigue may:

  • Lower our quality of everyday life
  • Interfere with relationships with friends and loved ones
  • Make going to work or caring for children much more difficult
  • Make it more challenging to follow the advice of our healthcare team
  • Slow down or interfere with healing
  • Put us at risk for suicide

Fatigue is treatable, but many patients with fatigue don’t report these symptoms to their health care team. Maybe we think it’s just a natural or non-negotiable part of having cancer. It’s not. Like many health conditions, fatigue can be treated and managed. There are many things that we can do to create notable reductions in fatigue.

The health professionals overseeing your treatment are experienced and skilled in dealing with fatigue in cancer patients. Work with them to find the medical causes for your elevated fatigue.

In the meantime, we’ve put together several things you can do today to help overcome cancer-related fatigue.

Tips for overcoming cancer-related fatigue

First, talk to your medical team so they can test and treat possible physical causes. Next, try these intentional lifestyle tips to help manage treatment side effects.


A poor diet lowers our physical and emotional energy and leaves our body without the fuel it needs to heal. Try these tips to boost your nutrition:

1. Stay hydrated

Your body is made of water. Elevated fatigue is a common symptom of dehydration, even among healthy people. Try to get a full 64 ounces of water per day.

2. Reduce alcohol consumption

Cut down alcohol intake by ½ or eliminate it entirely. Alcohol is a depressant and can make fatigue worse. Plus, it makes it harder to get a restful night’s sleep.

3. Try nutrition supplements

Try high-quality supplements. The right supplements can provide essential micro-nutritional support to convert food into energy. 

4. Eat a healthy breakfast

Start your day with a nutrient-dense plant-forward breakfast. Our medical advisors recommend a high-quality protein shake, green juice with turmeric and ginger, and steel-cut oatmeal to give a surge of morning energy.

5. Eat a healthy lunch

Eat more at breakfast and lunch to deliver more energy throughout the day. So, even though many of us make dinner the biggest meal, we need calories during the day to combat fatigue. If you don’t have an appetite, try eating smaller, more frequent meals.

6. Increase your fiber intake

Bump up your intake of fiber through vegetables, fruits, whole grains and beans. Even though it may feel hard right now, eating more of these foods provides nutrients that boost our energy levels. Now might be a good time to try out a new recipe. Here are some cookbooks we love that have unexpected options.

  • Right now, focus on adding in healthy (like fruits) versus cutting out unhealthy (like sweets).
  • Add duos or trios of veggies to each meal. Instead of a side of green beans, mix it up with a trio of green beans, tomatoes, and edamame or a combination of other veggies you like.
  • Remember this: The darker the vegetable, the more nutrients it has. Prioritize purple, dark green, and red vegetables over light green and yellow veggies. But all choices are good choices! Any vegetable is better than no vegetable.
  • Ethnic cuisines, like Mediterranean and Asian, offer flavorful and healthful dishes.

7. Simplify food prep

It’s overwhelming to prepare healthy food when we have low energy. When friends and family offer help, take it! Invite them over to cook or let them bring over a meal—and don’t forget to ask for a salad.

8. Learn from a pro

A registered dietitian or nutritionist can help you learn more about foods that boost energy and reduce fatigue. Talk to someone on staff at your hospital or find an expert with experience in cancer-related side effects.

What’s the difference between a nutritionist and a registered dietician? Both are trained in nutrition and diet, but a registered dietitian has advanced clinical training. We suggest working with a dietician.


When we’re tired, it may seem best to rest as much as possible. But physical inactivity can actually make fatigue worse. The trick is to establish the right pattern.

Many patients with cancer experience anxious, sleepless nights and lethargic days (also known as “excessive rest syndrome”). The goal is to break the cycle and replace it with healthful activity during the day and restful sleep at night. Here’s how:

1. Focus on quality rest

Sleep well (at night). If you have trouble falling asleep, staying asleep, or waking up too early try some of these products.

2. Limit naps during active treatment

After treatments end, we might need to take a nap during the day. While fatigued patients certainly benefit from the positive effects of more sleep, too much of a good thing isn’t a good thing at all. Try to limit it to less than an hour or you may have trouble falling asleep at night and returning to a normal routine.

3. Prioritize daily activities

Don’t deplete energy with things that don’t really matter. Use your energy to take care of the most important things in life first.

4. Get help

Accept help from friends or loved ones with day-to-day tasks like cleaning, shopping, or watching children. Use the extra time to go for a walk or try that yoga class. Remember, people like to help and it’s a gift to let them play a role in our life after a cancer diagnosis.

Mend Together has a convenient Volunteer Calendar to communicate how friends and family can help. Create your free account here

5. Get moving

“A sedentary lifestyle is a bad idea no matter what, but it is a really bad idea for cancer patients,” advises Dr. Keith Block, medical director of the Block Center for Integrative Cancer Treatment.

While we may think cancer earns us a break from physical activity, it can actually get in the way of healing. Inactivity leads to muscle loss and may compromise our immune system. Bed rest doesn’t save our energy, it depletes it. For every hour you’re awake, try to move for at least five minutes, even if you’re very sick. The beneficial effects of moving are well worth it.

6. Try yoga

It gives us a double bang for our buck. We get the positive effects of exercise on fatigue while also reducing stress, both of which help manage fatigue. One of our favorite types of yoga is Bikram (or hot) yoga. For those of us who enjoy warmer temperatures, it’s particularly healing (and addictive). Find a place to practice by searching for a Bikram or Original Hot Yoga studio.

Even tiny improvements in our habits can make a difference. Walking as little as 10 minutes at a time or lifting very light weights can develop more resistance to fatigue. Scale up your activities during times of positive energy levels.


1. Seek counseling

Fatigue in adult survivors is a common symptom of depression. Many of us benefit from talk therapy with a licensed certified social worker (LCSW), psychologist or psychiatrist.

2. Be open to an antidepressant

Your mental health counselor may suggest an antidepressant. Antidepressants can help turn chronic sad days into sunny ones. In addition to seeing an improvement in fatigue, antidepressants can have positive effects on all aspects of quality of life.

Ignore any social stigma you may feel about antidepressants— they can be life-changing if you are clinically depressed. There are also natural supplements that can help regulate mood.

3. Experiment as needed

It often takes some trial and error to find the right antidepressant for you. There are many formulations with different strengths and side effects. If you start this process, muscle through it with your practitioner until you find a solution that works for you.

Many people find a combination of therapy and medication to be most effective.

How can friends, family, and colleagues help?

If our friend or loved one is suffering from fatigue, here’s how we can help.

1. Provide support

Listening to and validating our friends can mean a lot to them. Also, symptoms of fatigue are not always predictable, and some days are worse days than others. Asking “How are your spirits?” is a great way to check-in.

2. Offer specific (not general) help

If our friend or colleague has young children or a critter, offer to help for an hour or two. Maybe we can organize a group to provide some meals or pay for a house cleaner. Know that it’s often hard for patients to ask for help, so don’t wait for a request. Reach out with specific chores we’re willing to do and let them choose.

3. Attend a class together

We know being more active can help with feelings of fatigue, but sometimes it’s hard to find motivation. Suggest going for a regular weekly walk or offer to join them at an exercise class or yoga session. This sort of support can be critical and is even better if you make it a regular part of both your routines.

A little goes a long way

Cancer fatigue can feel debilitating, but small, inspired steps can raise energy levels. Watch the difference it makes. Get the support you need by creating a free Mend Together account.

Errol J. Phillip has a PhD in Clinical Psychology from Notre Dame and is a former Clinical Research Psycho-Oncology Fellow at Memorial Sloan Kettering Cancer Center.

Lisa Lefebvre is the Founder of Mend Together. She has experience recovering from 8 cancer-related surgeries, chemotherapy treatments, radiation protocols and hormone suppression therapy.