Medically Reviewed By William C. Lloyd III, MD, FACS

What is fatigue?

A fatigue definition is a feeling or sensation of being tired, weary, exhausted, weak or low energy. It can occur during or after routine activities. Fatigue can also be a lack of energy to begin such activities. Unlike physical tiredness, a good night’s sleep often provides no relief from fatigue. Fatigue is a symptom of a wide variety of mild to serious diseases, disorders and conditions. Fatigue causes include infection, inflammation, insomnia, trauma, cancer, chronic diseases, autoimmune diseases, and mental health problems.

Fatigue can occur in any age group or population. However, it is particularly common in the elderly and in people with chronic diseases. Depending on the cause, fatigue symptoms can be brief and disappear quickly, such as after exertion or a single night of insomnia. It can also be chronic and ongoing over a longer period of time, such as with chronic fatigue syndrome (CFS), depression, or heart failure.

Fatigue can be a symptom of a serious or life-threatening condition. If you have fatigue that does not go away with good sleep habits and good nutrition, see your doctor promptly. If you, or someone you know, is having fatigue with chest pain, difficulty breathing, dizziness, or a change in consciousness or alertness, seek immediate medical care (call 911).

What other symptoms might occur with fatigue?

Fatigue may occur with other symptoms that vary depending on the underlying disease, disorder or condition. For example, fatigue due to hypothyroidism may occur with dry or brittle hair, hair loss, unusual weight gain, and possibly goiter (neck swelling due to enlargement of the thyroid gland). Fatigue from depression may occur with excessive crying, sleep problems, and apathy.

Symptoms that may occur with fatigue include:

  • Apathy (feeling indifferent to your surroundings)
  • Depression
  • Loss of appetite
  • Pain

Serious symptoms that might indicate a life-threatening condition

In some cases, fatigue can indicate a serious or life-threatening condition, such as acute heart failure or gastrointestinal bleeding, which should be immediately evaluated in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms:

  • Change in level of consciousness or alertness, such as passing out or unresponsiveness
  • Change in mental status or sudden behavior change, such as confusion, delirium, lethargy, hallucinations and delusions
  • Dizziness or lightheadedness
  • High fever (higher than 101°F)
  • Not producing any urine

What causes fatigue?

A wide variety of diseases, disorders or conditions can cause fatigue. This includes anemia, low blood pressure (hypotension), chronic fatigue syndrome, and Addison's disease. Fatigue can be due to relatively mild and temporary conditions, such as jet lag. It can also be caused by serious or life-threatening conditions, such as organ failure or cancer. Fatigue that lasts for more than six months, does not go away with rest, and is not due to a known mental or physical illness is defined as chronic fatigue syndrome (CFS). The cause of CFS is not known at this time.

Common causes of fatigue

Fatigue can be due to common conditions including:

  • Anemia
  • Chronic pain
  • Dehydration
  • Depression
  • Endocrine abnormality (thyroid, adrenal gland, etc.)
  • Fever
  • Hyperthyroidism (overactive thyroid gland) or hypothyroidism (underactive thyroid gland)
  • Lifestyle habits
  • Pregnancy

Other causes of fatigue

Fatigue can be due to a variety of other diseases, disorders and conditions including:

  • Addison’s disease (deceased production of hormones by the adrenal glands)
  • Cancer
  • Chronic fatigue syndrome
  • Diabetes (chronic disease that affects your body’s ability to use sugar for energy)
  • Fibromyalgia (syndrome associated with long-term, body-wide pain points)
  • Toxic environmental exposure

Medications that can cause fatigue

Always tell your doctor about any medications or supplements you are taking, including prescription and over-the-counter medications and herbal or alternative supplements. The following medications may be a possible cause of fatigue:

  • Antidepressants
  • Antihistamines
  • Sleeping medications, tranquilizers, sedatives, and anti-anxiety medications
  • Steroids

When should you see a doctor for fatigue?

Most causes of fatigue are not serious. Fatigue often responds to adequate rest, stress reduction, good nutrition, and hydration. If fatigue persists for more than two weeks despite these efforts, make an appointment with your doctor. Also, see your doctor if fatigue is interfering with your daily activities.

There are times when seeing a healthcare provider is the safest option to diagnose more serious causes. See a doctor promptly when fatigue occurs along with:

  • Feelings of sadness, hopelessness or depression
  • Fever, weakness, or unintended weight loss
  • Insomnia or other sleep problems

Call 911 or go to your nearest emergency room for fatigue when:

  • You are not producing much urine or have other signs of dehydration.
  • You have thoughts of harming yourself or someone else or you are thinking about suicide.

How do doctors diagnose the cause of fatigue?

Diagnosing the cause of fatigue usually starts with a complete medical history and physical exam. The exam will be thorough and cover your heart, lungs, nervous system, thyroid gland, abdomen, lymph nodes, and eyes, ears, nose and throat.

Questions for diagnosing the cause of fatigue

To best understand your medical history, your doctor may ask you several questions related to your fatigue including:

  • When did your fatigue start? Did it begin suddenly or gradually?
  • Describe the fatigue. Is it constant or intermittent? Is it mild, moderate or severe? Does it occur with or after certain activities or events, such as stress, exercise, or just before the menstrual period?
  • How long have you had fatigue?
  • What, if anything, seems to make your fatigue better or worse?
  • What other symptoms do you have with fatigue?
  • What other medical conditions do you have?
  • What medications are you taking?
  • How much sleep do you get on a regular basis? How easily do you fall asleep? How often do you awaken during the night?
  • How often do you exercise?
  • Do you smoke, drink caffeine, or use alcohol or drugs?

Using your answers and the results of the exam, your doctor may order testing. This could include:

  • Basic blood tests to check red blood cell counts, white blood cell counts, blood sugar levels, and markers of inflammation
  • Kidney and liver function tests
  • Thyroid hormone levels

It is not always possible to diagnose an underlying cause or condition. If the problem persists and your provider is unable to determine a cause, seeking a second opinion may give you more information and answers.

What are the treatments for fatigue?

Fatigue treatment is entirely dependent on the underlying cause. The goal is to eliminate the cause, if possible, or reduce the impact of fatigue on your quality of life. Your treatment plan may include any of the following:

  • Medications, including pain relievers and medicines to treat specific medical conditions, such as heart problems, low thyroid hormone levels, and depression

Home remedies for fatigue

People dealing with fatigue can benefit from good sleep hygiene, which includes:

  • Avoiding daytime naps
  • Getting regular exercise
  • Having routine sleep and wake times and only using the bed for sleep and sex
  • Keeping your room cool and dark
  • Not eating or using electronics too close to bedtime and taking time to wind down before bed

Your goal should be sleeping 7 to 9 hours per day. It is also important to eat a healthy diet, stay hydrated, and maintain your body weight within a normal range.

Alternative treatments for fatigue

Alternative treatments may help some people with fatigue. Strategies include:

  • Brain games, which may help stimulate the brain and reduce brain fog that may accompany fatigue
  • Relaxation techniques, such as meditation and mindfulness
  • Mind-body exercises, such as Yoga, Pilates, and Tai Chi
  • Supplements, such as magnesium and NADH (nicotinamide adenine dinucleotide)

Talk with your doctor before adding supplements or changing your diet or exercise routine.

What are the potential complications of fatigue?

Complications associated with fatigue can be progressive. It is important to visit your healthcare provider promptly when you experience unexplained fatigue. Once the underlying cause is diagnosed, following the treatment plan you and your healthcare provider design specifically for you can help reduce potential complications including:

  • Decreased overall quality of life
  • Inability to perform daily tasks and disability
  • Increased risk of physical trauma due to accidental injuries caused by inattention and slowed responses
  • Poor quality of life
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Dec 10
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.