Asthenia - Weakness

Weakness is usually defined as a lack of or decrease in muscle strength. It is different from fatigue, which is a loss of energy.

What is going on in the body?

Weakness can be used to describe a mental and physical state in which someone doesn't have the muscle strength, for example, to walk. It is common and sometimes difficult to evaluate. Weakness has many causes.

What are the causes and risks of the condition?

Weakness has many causes that are best grouped into these categories:

Other causes are also possible. Sometimes, no cause is found.

What are the signs and symptoms of the condition?

Weakness itself may be a symptom. So when someone complains of weakness, the healthcare provider will need to know more details such as:

Other symptoms may also be important, such as weight loss, fever, depression, or pain.

How is the condition diagnosed?

Figuring out the cause of weakness starts with a history and physical exam. In some cases, this may be all that the healthcare provider needs to make a diagnosis. In other cases, further testing is needed.

Which tests are done depends on the suspected cause. For example, blood tests such as a chem-7 can be used to diagnose salt imbalances. Chest x-rays may show pneumonia, and cranial CT scans can help detect a stroke. Special nerve and muscle tests, such as an electromyogram or nerve conduction velocity test, may help diagnose myasthenia gravis or diabetic neuropathy. Other tests may be needed as well.

What can be done to prevent the condition?

Prevention depends on the cause. For example, weakness due to lack of exercise can be prevented with regular exercise. Weakness due to alcohol or diabetic neuropathy can be prevented by not drinking alcohol or controlling diabetes with a proper diet and medications. Many cases of weakness cannot be prevented.

What are the long-term effects of the condition?

Weakness, when severe, may prevent people from doing normal activities. Most of the serious long-term effects are due to the cause. For example, people who have had a stroke may become paralyzed for life. People who are weak from an infection may have no long-term effects after treatment. People with cancer may die if treatment fails.

What are the risks to others?

Weakness is not contagious and poses no risk to others. But if the cause of weakness is an infection, the infection may be contagious.

What are the treatments for the condition?

Treatment depends on the cause. For example, an infection may be treated with antibiotics. An autoimmune disorder may be treated with drugs to suppress the immune system, such as corticosteroids. People with cancer may need surgery, chemotherapy, or radiation therapy. People with a muscle injury may need to apply ice to the muscle, take pain medication and rest.

What are the side effects of the treatments?

Side effects depend on the treatments used. All medications have possible side effects. For example, antibiotics may cause allergic reactions and stomach upset. Corticosteroids can cause weight gain, a puffy-looking face, and weak bones. Surgery carries a risk of bleeding and infection.

What happens after treatment for the condition?

If the weakness goes away or the cause is "fixed," people can usually resume normal activities fairly soon. In other cases, treatment may not end. For example, those with severe heart, liver, or kidney disease usually need treatment for life.

How is the condition monitored?

People can monitor their weakness and how it responds to treatment at home. Further monitoring depends on the cause. For example, those with diabetes need regular check-ups and blood tests.

Author:Adam Brochert, MD
Date Written:
Editor:Wendel, Sandra J., BA
Edit Date:06/26/00
Reviewer:Eileen McLaughlin, RN, BSN
Date Reviewed:08/09/01

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