Fatigue – Causes and symptoms


Also called: Weariness, Exhaustion, Tiredness

Reviewed By:
David Slotnick, M.D.


Fatigue is a lack of energy or a feeling of debilitating tiredness. It affects almost everyone at some point. It can be a normal response to overexertion, stress or minor illness such as a cold. However, it can also be a symptom of a medical condition or signal that a disease has worsened.

Most people can recover from fatigue due to nonmedical origins in a short period of time. However, continually getting inadequate amounts and quality of sleep can create a sleep debt even in otherwise healthy people. Long-term sleep debt can cause health problems that require medical attention. Fatigue alone can also significantly influence the ability of people to function.

The many conditions that can cause fatigue include pain disorders, diabetes, heart disease, lung problems, mental conditions, digestive disorders or cancer. It may also be due to certain medications or other medical treatments.

Diagnosis typically begins with a review of the patient’s medical history and a physical examination. Factors important in the history include current medical conditions, medications and pattern of fatigue.

Patients may be diagnosed with chronic fatigue syndrome if they have debilitating fatigue for at least six months and meet certain other criteria.

Treatment focuses on addressing the underlying cause of fatigue and achieving adequate rest. Possible options may include sleep therapy, exercise, or changes in diet or medication People can help prevent fatigue by getting regular medical care and practicing good health habits such as exercise, diet, stress management and regular sleep.

About fatigue

Fatigue is a lack of energy or feeling of debilitating tiredness. It may be a normal physical response to factors such as:

  • Lack of sleep
  • Physical exertion
  • Stress or anxiety
  • Depression or grief
  • Boredom
  • Certain medications, such as for high blood pressure or cancer

Fatigue associated with these factors may last days, weeks or months. It often disappears after the patient becomes rested. It is also a common symptom of pregnancy, and of minor illnesses such as colds.

Fatigue can also be due to many serious or long-term diseases ranging from diabetes to fibromyalgia. This fatigue may not be relieved as easily.Such patients may experience chronic fatigue, often defined as lasting six months or longer . Chronic fatigue can impede on normal functioning and interfere with a patient’s ability to:

  • Concentrate at work or school
  • Perform household tasks
  • Maintain normal relationships
  • Derive pleasure from favorite activities

Patients who have chronic fatigue and meet certain other diagnostic criteria may be diagnosed with chronic fatigue syndrome.

Recent research indicates that disabling short-term and long-term fatigue may have genetic roots and tend to run in families.

Fatigue can impair memory, trigger headaches, induce muscle pain and cause accidents. Even though fatigue can greatly affect patients’ lives, many individuals do not report it to healthcare professionals. Patients experiencing fatigue are encouraged to discuss the condition with their physician, who can determine the possible cause.

Other symptoms related to fatigue

Patients usually characterize fatigue as a feeling of lacking energy or feeling weak, tired, worn out, exhausted, weary or slow. Fatigue may be associated with an increased need for rest or the inability to regain energy after rest periods.

Psychological symptoms associated with fatigue may include:

  • Lack of motivation
  • Lethargy
  • Sadness
  • Irritability
  • Frustration
  • Apathy

There are also physical responses to fatigue, including:

  • Inability to sleep
  • Oversleeping
  • Drowsiness
  • Feeling of heaviness in the arms and legs
  • Muscle pain
  • Headaches

Potential causes of fatigue

A wide range of physical and psychological conditions can cause fatigue. Among them are:

  • Allergies, asthma and respiratory disorders.

  • Anemia (insufficient number of red blood cells).

  • Cancer. Many cancer treatments also cause fatigue.

  • Cardiovascular disorders such as heart failure, coronary artery disease and endocarditis.

  • Digestive problems including inflammatory bowel disease and liver disease.

  • Emotional disorders including depression, eating disorders and drug or alcohol abuse.

  • Endocrine conditions such as diabetes, thyroid disorders and Addison’s disease (underactive adrenal glands).

  • Kidney diseases including chronic renal failure, and treatments including dialysis.

  • Many infectious conditions. Examples include colds, flu, encephalitis, HIV/AIDS, Lyme disease, mononucleosis, parasitic infection, rabies, tuberculosis and West Nile virus.

  • Neurological diseases such as multiple sclerosis.

  • Many pain conditions. These include arthritis, chronic fatigue syndrome, fibromyalgia, headaches, lupus, myofascial pain syndrome, myositis, polymyalgia rheumatica, sarcoidosis, sickle cell anemia and temporal arteritis.

  • Sleep disorders including insomnia, narcolepsy, night terrors and sleepwalking, and sleep-disrupting conditions ranging from apnea to restless legs syndrome to prostate enlargement (benign prostatic hyperplasia).

Other sources of fatigue include poor eating habits, malnutrition, excess consumption of caffeine or alcohol, dehydration and pregnancy.

Medication is another factor that may contribute to fatigue. A number of prescription and over-the-counter medications can cause fatigue, including antidepressants, antihistamines, antihypertensives (drugs used to treat high blood pressure), anticonvulsants, chemotherapy drugs, corticosteroids, sleeping pills and triptans (a class of migraine drugs).

Diagnosis methods for fatigue

Diagnosis of fatigue typically begins with a physician obtaining a detailed medical history and discussing the condition with the patient. Patients should also report any additional symptoms that make fatigue worse, such as:

  • Nausea or vomiting
  • Pain
  • Constipation
  • Diarrhea
  • Shortness of breath
  • Inability to keep liquids or food down
  • General weakness

To accurately assess fatigue, physicians may ask patients to rate their fatigue on a scale of zero to 10, where a rating of 10 indicates maximum fatigue. Patients may be evaluated for contributing conditions, such as anemia or infections. Physicians evaluate factors such as:

  • The pattern of fatigue (e.g., when it began, how long it has lasted, etc.)
  • Current medications
  • Sleep patterns
  • Eating habits
  • Daily activities

A physical examination may be performed after the medical history. During an evaluation for fatigue, physicians often focus on examining the heart, lymph nodes and thyroid gland. Blood tests and urine tests may be ordered to identify or rule out certain conditions.

People with long-lasting fatigue do not necessarily have chronic fatigue syndrome (CFS). Patients must meet two criteria to be diagnosed with CFS, according to the U.S. National Institutes of Health (NIH):

  • Have severe, chronic fatigue for six months or more, with other known causes ruled out by clinical diagnosis

  • Have four or more of the following symptoms for the previous six months or longer:

    • Substantially impaired concentration or short-term memory
    • Sore throat
    • Tenderness in the lymph nodes of the armpits or neck
    • Muscle pain
    • Multiple joint pains without swelling or redness
    • Headaches of a new type, pattern or severity
    • Sleep that does not refresh
    • Malaise after exertion

Treatment and prevention of fatigue

Treatment of fatigue often involves addressing the underlying condition. If a medication or other medical treatment is a contributing factor, the patient’s treatment plan may be adjusted where feasible.

Treatment methods for fatigue may include:

  • Exercise. Many patients can help combat fatigue with regular exercise, which can:

    • Enhance their mood
    • Increase their energy
    • Improve their endurance, strength and stamina
    • Increase their appetite
    • Facilitate sleep (if completed at least several hours before bedtime)
    • Prepare them for the challenges of other conditions and their treatments

Patients are generally advised to begin with short periods of low-intensity exercise, such as leisurely walking, and gradually increase the duration and intensity level of exercise over time (when appropriate). In many cases of individuals experiencing chronic pain or conditions, exercising is difficult. Patients should speak with their healthcare professionals to determine appropriate exercises for their condition.

  • Schedule of activity and rest. Patients who experience fatigue should prioritize their daily activities and use a schedule to conserve their energy. A physician or occupational therapist can help devise an activity and rest program that allows the patient to conserve the maximum amount of energy. Patients may reduce fatigue and improve their sleeping habits by:

    • Lying down only when ready for sleep
    • Limiting nap times during the day to allow sleeping at night
    • Increasing their activity level during the day
    • Eliminating distracting noises during sleep times
    • Eliminating foods at bedtime that could interfere with sleep

Patients should set realistic activity goals and, as needed, avoid overexerting themselves by using equipment aids (e.g., a ramp instead of stairs or an electric cart at the supermarket). These aids can help patients conserve energy, especially if the activities can cause pain in addition to fatigue.

Patients may also benefit from enlisting the help of others when errands and housework become too difficult. In addition, patients who work may choose to speak with their employer about modified responsibilities and flexible scheduling if need be. Many patients also benefit from maintaining an activity diary, which allows them to identify activities that are particularly taxing.

  • Maintain adequate hydration and nutrition. Patients are sometimes advised to drink a minimum of eight glasses of liquids every day to remain sufficiently hydrated. They should also eat a balanced and nutritious diet with enough calories, complex carbohydrates (vegetables, fruits and whole grains), proteins, beneficial fats (e.g., monounsaturated and omega-3) and vitamins to provide sustained energy sources and help the body meet its energy demands.

Patients may choose to speak with a dietician regarding ways to maximize their nutritional intake. Patients may also benefit from taking a multivitamin.

  • Reduce and manage stress. Patients experiencing fatigue may benefit from reducing their stress. This can be achieved by learning stress management and relaxation techniques, such as meditation and yoga. Treatments such as biofeedback, hydrotherapy or massage therapy may help.

  • Avoid activities that contribute to their pain. Patients should determine which activities and exercises can be tolerated without adding to their pain. They should choose activities that help lessen their fatigue and improve their well being.

People experiencing fatigue are often advised by their physician to avoid stimulants. Caffeine and other stimulants are not effective in the treatment of fatigue because they may worsen the disorder in the long run by disturbing sleep. Alcohol, nicotine and illegal drugs should also be avoided. In addition, a physician may advise against taking sedatives, which can also worsen the condition.  

Patients are encouraged to monitor the level of their fatigue and contact their physician should its severity increase.

Questions for your doctor regarding fatigue

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about fatigue:

  1. Why do I always feel tired?
  2. Are my medications making my fatigue worse?
  3. What related symptoms might I experience?
  4. Do I need to have any diagnostic tests?
  5. How can I relieve my fatigue?
  6. How long is my fatigue likely to last?
  7. Are there any alternative treatments that could help my fatigue?
  8. Can my diet affect my fatigue?
  9. How can exercise reduce my fatigue, and when should I avoid exercise?
  10. How do I know if I have chronic fatigue?
  11. Could I have chronic fatigue syndrome? How is it defined and diagnosed?
Scroll to Top