Weakness and Fatigue

Topic Overview

Weakness and fatigue are terms that are often interchanged but in fact
describe two different sensations. It is important to know exactly
what you mean when you say, "I feel weak" or "I am fatigued," because
it can help you and your health professional narrow down the possible
causes of your symptoms.

Weakness is a lack of physical or muscle strength and the feeling that
extra effort is needed to perform daily activities that require you to
move your arms, legs, or other muscles.
Fatigue is a feeling of tiredness, exhaustion, or lack of energy.
Both weakness and fatigue are symptoms, not diseases. Because these
symptoms can be caused by many other health problems, the importance
of weakness and fatigue can only be determined when other symptoms are
evaluated.

Weakness
General weakness often occurs after you have overexerted yourself,
such as by taking an extra-long hike. You may feel weak and tired or
your muscles may be sore. These sensations usually clear up within a
few days.

Rarely, generalized muscle weakness may be caused by another health
problem, such as:

Hypothyroidism or hyperthyroidism
Guillain-Barré syndrome
Myasthenia gravis
Muscle weakness that is getting progressively worse requires a visit
to a health professional.

Sudden muscle weakness and loss of function in one area of the body
can indicate a serious problem within the brain (such as a stroke or
transient ischemic attack) or spinal cord or with a specific nerve in
the body.

Fatigue
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. Any illness, such as a cold or the flu,
may cause fatigue, which usually goes away as the illness clears up.
Most of the time, mild fatigue occurs with a health problem that will
improve with home treatment and does not require a visit to a health
professional.

A stressful emotional situation may also cause fatigue. This type of
fatigue usually clears up when the stress is relieved.

Many prescription and nonprescription medications can cause weakness
or fatigue. The use or abuse of social drugs, such as alcohol,
caffeine, or illegal drugs, can cause fatigue.

A visit to a health professional is usually needed when fatigue occurs
with other more serious symptoms, such as increased breathing
difficulties, signs of a serious illness, abnormal bleeding, or
unexplained weight loss or gain.

Fatigue that lasts longer than 2 weeks usually requires a visit to a
health professional. This type of fatigue may be caused by a more
serious health problem, such as:

Anemia.
Coronary artery disease.
Diabetes.
Heart failure.
Hypothyroidism or hyperthyroidism.
Kidney disease.
Liver disease.
Chronic fatigue syndrome is an uncommon cause of severe, persistent
fatigue.

If fatigue occurs without an obvious cause, it is important to
evaluate your mental health. Fatigue is a common symptom of mental
health problems, such as anxiety or depression. Fatigue and depression
may become so severe that you may consider suicide as a way to end the
pain. If you think your fatigue may be caused by a mental health
problem, a visit to a health professional is needed.

Review the Emergencies and Check Your Symptoms sections to determine
if and when you need to see a health professional