Fatigue is a feeling of weariness, tiredness, or lack of energy.
Fatigue is different from drowsiness. Drowsiness is feeling the need to sleep. Fatigue is a lack of energy and motivation. Drowsiness and apathy (a feeling of not caring about what happens) can be symptoms that go along with fatigue.
Fatigue can be a normal and important response to physical activity, emotional stress, boredom, or lack of sleep. Fatigue is a common symptom, and it is usually not due to a serious disease. But it can be a sign of a more serious mental or physical condition. When fatigue is not relieved by enough sleep, good nutrition, or a low-stress environment, it should be evaluated by your doctor.
There are many possible causes of fatigue, including:
- Anemia (including iron deficiency anemia)
- Depression or grief
- Iron deficiency (without anemia)
- Medicines such as sedatives or antidepressants
- Persistent pain
- Sleep disorders such as insomnia, obstructive sleep apnea, or narcolepsy
- Thyroid gland that is underactive or overactive
- Use of alcohol or drugs such as cocaine or narcotics, especially with regular use
Fatigue can also occur with the following illnesses:
- Addison disease
- Anorexia nervosa or other eating disorders
- Arthritis, including juvenile rheumatoid arthritis
- Autoimmune diseases such as systemic lupus erythematosus
- Congestive heart failure
- Infection, especially one that takes a long time to recover from or treat, such as bacterial endocarditis (infection of the heart muscle or valves), parasitic infections, hepatitis, human immunodeficiency virus (HIV) AIDS, tuberculosis, and mononucleosis
- Kidney disease
- Liver disease
Certain medicines may also cause drowsiness or fatigue, including antihistamines for allergies, blood pressure medicines, sleeping pills, steroids, and diuretics.
Chronic fatigue syndrome (CFS) is a condition in which symptoms of fatigue persist for at least 6 months and do not resolve with rest. The fatigue may be worsened with physical activity or mental stress. It is diagnosed based on the presence of a specific group of symptoms and after all other possible causes of fatigue are ruled out.
Here are some tips for reducing fatigue:
- Get enough sleep each night.
- Eat a healthy, well-balanced diet and drink plenty of water throughout the day.
- Exercise regularly.
- Learn better ways to relax. Try yoga or meditation.
- Maintain a reasonable work and personal schedule.
- Change or reduce your stressors, if possible. For example, take a vacation or resolve relationship problems.
- Take a multivitamin. Talk to your doctor about what is best for you.
- Avoid alcohol, nicotine, and drug use.
If you have chronic pain or depression, treating it often helps the fatigue. Be aware that some antidepressant drugs may cause or worsen fatigue. If your drug is one of these, your doctor may have to adjust the dosage or switch you to another drug. DO NOT stop or change any medicines without first talking to your doctor.
Stimulants (including caffeine) are not effective treatments for fatigue. They can make the problem worse when they are stopped. Sedatives also tend to worsen fatigue.
When to Contact a Medical Professional
Call your health care provider right away if you have any of the following:
- Confusion or dizziness
- Blurred vision
- Little or no urine, or recent swelling and weight gain
- Thoughts of harming yourself or of committing suicide
Call your provider for an appointment if you have any of the following:
- Unexplained weakness or fatigue, especially if you also have a fever or unintentional weight loss
- Constipation, dry skin, weight gain, or you cannot tolerate cold
- Wake up and fall back to sleep many times during the night
- Headaches all the time
- Are taking medicines, prescribed or non-prescribed, or using drugs that may cause fatigue or drowsiness
- Feel sad or depressed
What to Expect at Your Office Visit
Your provider will perform a complete physical examination, paying special attention to your heart, lymph nodes, thyroid, abdomen, and nervous system. You will be asked about your medical history, fatigue symptoms, and your lifestyle, habits, and feelings.
Tests that may be ordered include the following:
- Blood tests to check for anemia, diabetes, inflammatory diseases, and possible infection
- Kidney function tests
- Liver function tests
- Thyroid function tests
Treatment depends on the cause of your fatigue symptoms.
Tiredness; Weariness; Exhaustion; Lethargy
Bennett RM. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 274.
Thames TA, Karrh LR, Bajorek E, Higgins CC. Fatigue. In: Paulman PM, Harrison J, Paulman A, Nasir LS, Collier DS, Bryan S. Signs and Symptoms in Family Medicine. Philadelphia, PA: Elsevier Mosby; 2012:chap 22.
Update Date 4/30/2015
Updated by: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.