Fatigue is a feeling of weariness, tiredness, or lack of energy.
Fatigue is different from
. 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:
(including
)
or
Iron deficiency (without anemia)
Medicines, such as sedatives or antidepressants
Persistent pain
such as
,
, or
Thyroid gland that is
or
Use of alcohol or drugs, such as cocaine or narcotics, especially with regular use
Fatigue can also occur with the following illnesses:
(a disorder that occurs when the adrenal glands don't produce enough hormones)
or other eating disorders
Arthritis, mainly adult or
Autoimmune diseases such as systemic
erythematosus
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,
, HIV/AIDS,
, and
Kidney disease
Liver disease
Certain medicines may also cause drowsiness or fatigue, including antihistamines for allergies, blood pressure medicines, sleeping pills, steroids, and diuretics (water pills).
(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.
Make sure your diet is healthy and well-balanced, and drink plenty of water throughout the day.
.
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, if you are able, take a vacation or resolve relationship problems.
Discuss with your provider whether any supplemental vitamins might help you.
Avoid alcohol, nicotine, and drug use.
If you have long-term (chronic) pain or depression, treating it often helps the fatigue. Be aware that some antidepressant medicines may cause or worsen fatigue. If your medicine is one of these, your provider may have to adjust the dosage or switch you to another medicine. 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:
Confusion or dizziness
Blurred vision
Little or no urine output
Recent swelling and weight gain
Thoughts of harming yourself or of suicide
Contact your provider for an appointment if you have any of the following:
Unexplained weakness or fatigue, especially if you also have a fever, unintentional weight loss, or regular sweats
Constipation, dry skin, weight gain, or you cannot tolerate cold
Wake up and fall back to sleep many times during the night
Frequent headaches
Are taking medicines, prescribed or non-prescribed, or using drugs that may cause fatigue or drowsiness
Feel sad or depressed
Insomnia
You will be asked about your medical history, fatigue symptoms, and your lifestyle, habits, and feelings.
Your provider will likely perform a complete physical examination, paying special attention to your heart, lymph nodes, thyroid, abdomen, and nervous system.
Tests that may be ordered include the following:
Blood tests to check for anemia, diabetes, inflammatory diseases, and possible infection
Treatment depends on the cause of your fatigue symptoms.
Tiredness; Weariness; Exhaustion; Lethargy
Clauw DJ. Fibromyalgia. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 253.
Regehr J. Fatigue. In: Kellerman RD, Heidelbaugh JJ, Lee EM, eds. Conn's Current Therapy 2025. Philadelphia, PA: Elsevier 2025:13-14.
Seller RH, Symons AB. Fatigue. In: Seller RH, Symons AB, eds. Differential Diagnosis of Common Complaints. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 14.
Updated by: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.