CANCER RELATED FATIGUE

After being diagnosed with cancer, you may feel tired, weak, listless, exhausted — basically like you have no energy. Sleep and rest don’t help. Your arms and legs may feel heavy and sluggish. You may have little desire to do anything and find it too tiring to eat or even walk to the door, let alone go to work or school. This is cancer fatigue.

Also called cancer-related fatigue by doctors, cancer fatigue is the most common side effect of cancer treatment. A 2023 study found that more than 70% of people diagnosed with cancer report having fatigue.

Cancer fatigue can dramatically affect your quality of life by making you feel too exhausted to participate in your usual activities. In many cases, physical fatigue can lead to mental fatigue and mood changes. But the good news is there are ways to ease fatigue, including exercise and diet changes.

What causes cancer fatigue?

There are a number of things that can cause cancer fatigue.

Being diagnosed with breast cancer: Breast cancer causes changes in your body that can lead to fatigue. Many breast cancers release proteins called cytokines, which have been linked to fatigue. Breast cancer also may change your body’s hormone levels and cause inflammation, both of which may contribute to fatigue.

Breast cancer treatment: Surgery, radiation therapy, chemotherapy, hormonal therapy, targeted therapy, and immunotherapy all may cause fatigue. Many medicines used to treat breast cancer affect both healthy cells and cancer cells. You may feel fatigue as your body works to repair or replace damaged healthy cells.

Treatment side effects: A number of side effects are also linked to fatigue, including pain, nausea, low red blood cell counts (anemia), low white blood cell counts, diarrhea, dehydration, trouble sleeping, and vomiting. These side effects can cause fatigue or make it more severe.

Your emotional health: People diagnosed with breast cancer often report feeling stressed, anxious, or depressed. All these emotions can lead to fatigue.

Not getting enough calories or nutrients: Breast cancer treatment side effects like nausea and taste changes — and even just the stress of a diagnosis — can make it hard to eat enough. But there are ways to get in more calories and nutrients to fight fatigue.

Pain medicines: A number of pain medicines, such as codeine, oxycodone, and morphine, are known to cause fatigue.

Lack of exercise. It may sound counterintuitive, but exercising, even gentle walking, can give you more energy. Not exercising can make you feel sluggish and tired.

Cancer fatigue symptoms

People describe cancer fatigue in many different ways. Common symptoms include:

feeling a lack of energy
sleeping less
sleeping more, but still feeling tired
having no interest in your normal activities
having trouble thinking or concentrating
feeling sad or cranky
paying less attention to your personal appearance
feeling so tired you can’t do even small tasks, like use the television remote or make a phone call
feeling very weak

How long does cancer fatigue last?

Unfortunately, if you have cancer fatigue, there is no way to know how long it might last or how severe it might be. Fatigue from breast cancer and breast cancer treatment can start before, during, or after treatment and last for weeks, months, or even years after you finish treatment.

It’s important to know that the effects of cancer fatigue can change from day to day. If you’re receiving chemotherapy, targeted therapy, or immunotherapy in cycles, the fatigue is often worse at the beginning of the cycle and then eases until the next cycle starts. If you’re receiving radiation therapy, fatigue usually gets worse as treatment goes on and then eases a few weeks or months after you finish treatment.

Managing cancer fatigue

If you think you have cancer fatigue, the first thing to do is to talk with your doctor. Many people think that fatigue is just part of cancer treatment, so they don’t mention it. Although fatigue is common, it can be treated and managed.

Usually, there is no single cause of cancer fatigue. So your doctor may add other clinicians to your care team, including palliative care professionals, nurses, social workers, physical therapists, pharmacists, cancer exercise trainers, and registered dietitians to help you manage fatigue.

It can help your care team develop strategies to ease fatigue if you keep a journal or log that includes:

all your breast cancer-related symptoms and treatment side effects
when each symptom and side effect started
how severe the symptoms and side effects are throughout each day
how you’re feeling physically and emotionally each day

Treating specific side effects, such as pain or anemia, can help ease cancer fatigue, but your doctor is likely to recommend other steps and therapies that can help manage fatigue.

Exercise

Exercise is considered the most effective non-drug treatment for cancer-related fatigue and is strongly recommended by the American Society of Clinical Oncology (ASCO).

Research consistently shows that regular physical activity can reduce fatigue during and after cancer treatment while improving physical function, mood, and quality of life.

Exercise programs may include:

Walking
Cycling
Swimming
Resistance or strength training
Yoga
Tai Chi

Combining aerobic exercise with strength training appears to provide the greatest benefit. Even light activity is often better than complete rest. Exercise programs should be tailored to your fitness level and treatment plan.

Nutrition & Hydration

Eating a balanced diet can help support energy levels during treatment.

Aim to include:

Whole grains
Fruits and vegetables
Lean protein
Fish
Nuts and seeds
Healthy fats such as olive or flaxseed oil

Staying well hydrated is also important, as dehydration can worsen fatigue.

If eating is difficult because of treatment side effects, ask your healthcare provider for a referral to a registered dietitian with experience in oncology nutrition.

Energy Conservation

Managing your energy wisely can help you accomplish important activities without becoming overly exhausted.

Strategies include:

Prioritize essential tasks.
Plan demanding activities for times of day when you have the most energy.
Pace yourself and take regular breaks.
Break large tasks into smaller steps.
Accept help from family and friends when available.
Consider assistive devices if recommended by your healthcare team.

Occupational therapists can provide additional strategies for conserving energy.

Improve Sleep

Good sleep habits can help reduce fatigue.

Consider:

Going to bed and waking up at the same time each day
Creating a relaxing bedtime routine
Limiting screen time before bed
Keeping the bedroom cool, dark, and quiet
Avoiding large meals, alcohol, and excessive caffeine close to bedtime

Short daytime naps (20–30 minutes) may help without interfering with nighttime sleep.

If you have ongoing insomnia, snoring, or other sleep concerns, discuss them with your healthcare provider.

Manage Stress and Emotional Well-being

Stress, anxiety, and depression can worsen fatigue.

Several approaches have been shown to help:

Cognitive behavioural therapy (CBT)
Mindfulness meditation
Relaxation techniques
Yoga
Counselling
Support groups
Journaling
Massage therapy
Acupuncture

Addressing emotional health is an important part of managing fatigue.

Rehabilitation

Physical therapists and occupational therapists can help improve endurance, strength, mobility, and independence through individualized rehabilitation programs.

These professionals can also recommend adaptive equipment and teach strategies to safely perform daily activities while conserving energy.

Pharmacological Options

There are no medications approved specifically for cancer-related fatigue, and non-drug approaches remain the preferred first-line treatment.

However, in selected patients with severe fatigue, healthcare providers may consider medications after evaluating for reversible causes.

Possible options include:

Psychostimulants, such as methylphenidate, which may improve alertness and reduce fatigue in some patients. Evidence is mixed, so they are not routinely recommended.
Modafinil may be considered in select individuals, particularly those with severe fatigue or excessive daytime sleepiness, although studies have shown inconsistent results.
Corticosteroids (such as dexamethasone) may provide short-term relief of fatigue in people with advanced cancer receiving palliative care. They are generally not recommended for long-term use because of potential side effects.

Any medication should be prescribed only after discussing the potential benefits and risks with your healthcare provider.

Integrative Therapies

Some complementary therapies have shown benefit for reducing cancer-related fatigue when used alongside standard medical care.

These include:

Acupuncture
Yoga
Tai Chi
Qigong
Mindfulness-based stress reduction
Massage therapy (for appropriate patients)

Discuss any complementary therapies with your healthcare team to ensure they are safe alongside your cancer treatment.

Ask for Help

Fatigue can make everyday activities more challenging. Accepting support from family, friends, or community resources can help conserve energy for the activities that matter most.

Remember that cancer-related fatigue is common, but it should not be ignored. If fatigue is affecting your daily life, talk with your healthcare team—effective strategies are available, and combining several approaches often provides the greatest benefit.