Fatigue (medical)

What Is Fatigue?

Fatigue is defined as extreme tiredness that can occur on both a mental and physical level. Exhausted, weary, tired, and lethargic are all words that are commonly used to describe fatigue. It is a state of persistent and unyielding exhaustion that isn’t eased by rest. It is a symptom that develops over time that can significantly decrease a person’s motivation, energy, concentration, and overall quality of life.

What Causes Fatigue?

Fatigue is typically linked to a person’s lifestyle habits. It is commonly related to a lack of exercise, and can also be linked to conditions such as depression and stress. Regular causes of fatigue include:

  • Lack of sleep
  • Lack of exercise
  • Excessive exercise
  • Excessive activity trying to meet the demands of everyday life
  • Unhealthy eating habits
  • Alcohol or drug use
  • Certain medications (antihistamines and cough medicines)

There are also certain conditions that are known to cause fatigue. These can include the following:

  • Anxiety
  • Depression (major depressive disorder)
  • Stress
  • Persistent pain
  • Ingestion of toxins
  • Chemotherapy
  • Cancer
  • Antidepressant medication
  • Thyroid problems
  • Diabetes
  • Heart Disease
  • Obesity
  • Sleep apnoea
  • Certain respiratory diseases



Fatigue generally appears in a gradual onset. Many times, a person will not realise they are tired until they feel completely depleted or exhausted. Some of the symptoms of fatigue a person can experience include:

  • Lack of energy
  • Feeling run down
  • Feeling tired all the time
  • Impaired memory
  • Trouble concentrating
  • Pain in muscles or joints
  • Weight loss
  • Fever
  • Chills
  • Chest Pain
  • Shortness of breath
  • Headache
  • Feeling tired after adequate sleep
  • Tenderness in the lymph nodes

Fatigue is often classified into three different concerns. These include:

  • Lack of motivation to begin or finish an activity or project
  • Tiring easily once beginning an activity or project
  • Problems concentrating or mental fatigue that inhibits the start or completion of an activity or project


Fatigue is considered a symptom of an underlying condition. It is necessary to identify the underlying condition causing fatigue before a treatment plan can be properly administered. The causes of fatigue can be mental, physical, or a combination of both.

Finding the cause of fatigue is done by a medical professional. It typically involves a complete medical history, including questions about the quality and quantity of fatigue the individual is experiencing. Alcohol and drug screening questions are also addressed, as fatigue is a common symptom of substance abuse. A full physical screening is also done to ensure there are no underlying medical conditions. Blood tests may also be taken to determine the cause of a person’s fatigue.

The treatment a person receives is dependent upon the underlying cause for the fatigue they are experiencing. Lifestyle changes can play a big role in treating fatigue. Eating well, staying hydrated, and getting regular exercise can help a person overcome fatigue. Avoiding drugs and alcohol, excessive amounts of caffeine, and getting regular rest can also help.

Engaging in various techniques to manage and reduce stress can also help with fatigue. For those experiencing fatigue due to depression, antidepressants can help, but aren’t considered a stand-alone treatment for fatigue.

Fatigue FAQ

Can fatigue be prevented?

When fatigue is considered a symptom, it means that it can be caused by several different things. Because fatigue has a gradual onset, it can be difficult to realise something is wrong. It is therefore difficult to prevent fatigue from occurring.

Does being overweight cause a person to feel fatigue?

Yes. Being overweight causes the need for more physical exertion to do regular tasks, which is something that can lead to fatigue. Consequently, being underweight can also cause fatigue.

What is one of the main reasons people feel fatigue?

Everyone suffers from fatigue for different reasons. One of the main however, is due to inactivity. Getting regular exercise can help a person overcome fatigue and increase their energy levels.

Does depression cause fatigue?

Stress, anxiety, and worry are all emotions that can cause a person to feel tired. Clinically diagnosed depression, such as major depressive disorder, can both cause fatigue and be a symptom of it.

External Links

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, Centers for Disease Control and Prevention, 2017

Fatigue, Mayo Clinic

Fatigue, MedicineNet, Benjamin Wedro, MD, FACEP, FAAEM & Charles Patrick Davis, MD, PhD

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