Fatigue is a feeling of weariness, tiredness, or lack of energy.
Tiredness; Weariness; Exhaustion; Lethargy
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 health care provider.
There are many possible causes of fatigue, including:
Fatigue can also occur with the following illnesses:
Certain medicines may also cause drowsiness or fatigue, including antihistamines for allergies, blood pressure medicines, sleeping pills, steroids, and diuretics (water pills).
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:
If you have long-term (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 provider may have to adjust the dosage or switch you to another drug. DO NOT stop or change any medicines without first talking to your provider.
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.
Contact your provider right away if you have any of the following:
Call your provider for an appointment if you have any of the following:
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:
Treatment depends on the cause of your fatigue symptoms.
Clauw DJ. Fibromyalgia, chronic fatigue syndrome, and myofascial pain. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 258.
Lindemann JC. Fatigue. In: Kellerman RD, Rakel DP, eds. Conn's Current Therapy 2021. Philadelphia, PA: Elsevier 2021:14-15.
Seller RH, Symons AB. Fatigue. In: Seller RH, Symons AB, eds. Differential Diagnosis of Common Complaints. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 14.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.