Weakness: Causes

What causes weakness?

Weakness is a feeling of being tired, exhausted, or experiencing a loss of strength. Weakness may or may not be accompanied by obvious or visible sickness. Short-term weakness may occur because of overwork, stress, or lack of sleep. You may also feel weakness after overcoming an illness, such as a cold or the flu. It is normal to feel some weakness after some physical activity.

You may also feel weakness as a symptom of depression. Long-term depression may indicate more serious emotional or psychological problems.

Weakness may also occur because of physical diseases or toxic disorders. Long-term (chronic) conditions, such as multiple sclerosis or an underactive thyroid may cause weakness. Short-term (acute) conditions, such as a pinched nerve or a urinary tract infection, may also lead to weakness. Other possible causes of weakness are toxic disorders, exposure to an insecticide, or shellfish poisoning.

Emotional or psychological causes of weakness

Weakness may be caused by emotional or psychological disturbances including:

• Depression
• Fatigue
• Lack of sleep
• Overwork
• Stress

Physical causes of weakness

Weakness can also be caused by chronic physical disorders including:

• Amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease; a severe neuromuscular disease that causes muscle weakness and disability)
• Anemia (low red blood cell count)
• Cancers
• Fibromyalgia (chronic condition that causes pain, stiffness and tenderness)
• Hashimoto’s thyroiditis (autoimmune disease resulting in hypothyroidism and low production of thyroid hormone)
• Hypothyroidism (underactive thyroid)
• Infections
• Multiple sclerosis (disease that affects the brain and spinal cord causing weakness, coordination, balance difficulties, and other problems)
• Muscle breakdown (rhabdomyolysis)
• Muscular dystrophy (inherited disorder that causes a progressive loss of muscle tissue and muscle weakness)
• Myasthenia gravis (autoimmune disorder that causes a progressive loss of muscle tissue and muscle weakness)
• Polymyositis (widespread inflammation and weakness of muscles)

Serious or life-threatening causes of weakness

• Arrhythmias (irregular heart beats)
• Dehydration (loss of body fluids and electrolytes, which can be life threatening when severe and untreated)
• Kidney failure
• Myasthenia gravis crisis
• Myocardial infarction (heart attack)
• Myxedema coma (life-threatening complications of hypothyroidism)
• Pulmonary embolism (blockage of an artery in the lung due to blood clot)
• Ruptured aortic aneurysm
• Sepsis (life-threatening bacterial blood infection)
• Stroke
• Toxic ingestion, such as eating poisonous plants, mushrooms or chemicals

Questions for diagnosing the cause of weakness

To diagnose your condition, your doctor or licensed health care provider will ask you several questions related to your weakness including:

• How long have you felt weak?
• Do you feel weak all over or is it specific to one area of your body?
• Do you use alcohol or drugs?
• Are you in any physical pain or discomfort?
• Do you have any other symptoms?
• What medications are you taking?
• When did you first notice the feelings of fatigue or depression?
• Are you currently under the care of a mental health care professional?

What are the potential complications of weakness?

Because weakness can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care provider design specifically for you to reduce the risk of potential complications including:

• Difficulty performing daily tasks
• Difficulty sleeping
• Spread of cancer
• Spread of infection
• Withdrawal or depression

References:

Weakness. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003174.htm. Accessed May 31, 2011.

Weakness or fatigue. The Harvard Medical School Family Health Guide. http://www.health.harvard.edu/fhg/symptoms/weakness/weakness1.shtml. Accessed May 31, 2011.