What Are Common Causes of Fatigue

Tired woman in front of laptop computer

Tired woman in front of laptop computer

Fatigue is a feeling of tiredness, exhaustion, or lack of energy. You may feel mildly fatigued because of overwork, poor sleep, worry, boredom, or lack of exercise.

Most causes of fatigue will resolve in time without requiring a visit to the doctor.

Illness such as a cold or the flu, may cause fatigue, which usually resolves over a short period of time as the illness clears up. A stressful emotional situation may also cause fatigue. This type of fatigue usually clears up when the stress is relieved or becomes better controlled.

Many prescription and non-prescription medication can cause weakness or fatigue. These side effects usually resolve after you adjust to taking the medication. This may be seen with almost any drug; however, it is more common with blood pressure medications, and mood altering drugs (sedatives and antidepressants).

The use or abuse of alcohol, caffeine, or illegal drugs can cause fatigue.

A visit to a health professional usually is needed when fatigue occurs along with more serious symptoms such as pain, fever and chills, trouble breathing, abnormal bleeding, or unexplained weight loss or gain.

Fatigue that lasts longer than 1-2 weeks usually requires a visit to a health professional for further evaluation. This type of fatigue may be caused by a more serious health problem. Your physician will probably recommend test to evaluate you for the following potentially serious causes of fatigue:


A decrease in the amount of oxygen-carrying substance (hemoglobin) found in red blood cells (anemia). This may occur from blood loss related to intestinal bleeding, menstruation, and trauma. Chronic blood loss can result in iron deficiency which is required for the body to maintain appropriate hemoglobin levels required to carry oxygen. Nutritional deficiencies such as Vitamin B12 and folate can also result in anemia.

Cardiac Problems

If you have problems with the heart, such as coronary artery disease or heart failure, the ability of the heart to supply oxygen-rich blood to the heart muscle and the rest of the body will be impaired. This may result in poor exercise tolerance and fatigue.

A sudden change in your exercise tolerance can be an early sign of heart problems such as coronary artery disease. Approximately one third of patients with underlying heart disease have no signs or symptoms (such as chest pain or myocardial infarction). The first sign of any underlying problem in this one third is sudden death. Therefore, it is imperative that you seek further evaluation if you are noticing increased fatigue that is not easily explained.

Metabolic Disorders

Patients with metabolic disorders, such as diabetes, have impaired ability to utilize sugar (glucose) which is required to form energy for the body and organs.

Thyroid Abnormalities

Abnormalities of the thyroid gland may result in fatigue. It is important to determine if your thyroid gland is performing appropriately. If your gland is underactive you will require thyroid medication to restore your bodies normal levels. This will improve your energy and help with fatigue.

Fatigue may be related to an overactive or high thyroid level (hyperthyroidism). An overactive thyroid requires further evaluation. You may require radioactive ablation to destroy the overactive thyroid tissue. Other options include medication to control the symptoms caused by an overactive thyroid or medication to block the effects of the excess thyroid hormone in your body.

Kidney and Liver Abnormalities

Patients with kidney disease and liver disease have impaired ability to eliminate the waste products of the body. If the level of these chemicals get too high the patient will begin to experience weakness and fatigue.

Chronic Fatigue

Chronic fatigue syndrome is an uncommon cause of severe, persistent fatigue. It is commonly associated with a previous viral infection such as epstein barr virus.

Mental Health Problems

Mental health problems can result in fatigue. Patients suffering from anxiety and depression will frequently complain of fatigue. This is an important consideration if no medical explanation for fatigue can be found. Anxiety and depression can also develop in someone with other chronic health problems, so it is important that a thorough evaluation be performed by your health care provider.

The symptom of fatigue is commonly experienced by all of us during our day to day activities. If your fatigue is not improving with rest, or out of character from what you are accustomed to it is important to seek further medical evaluation by your health care provider.