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Weakness

Weakness is reduced strength in one or more muscles.

Causes

Weakness may be all over the body or in only one area. Weakness is more noticeable when it is in one area. Weakness in one area may occur:

You may feel weak but have no real loss of strength. This is called subjective weakness. It may be due to an infection such as the flu. Or, you may have a loss of strength that can be noted on a physical exam. This is called objective weakness.

Weakness may be caused by diseases or conditions affecting many different body systems, such as the following:

METABOLIC

BRAIN/NERVOUS SYSTEM (NEUROLOGIC)

MUSCLE DISEASES

  • Inherited disorder that involves slowly worsening muscle weakness of the legs and pelvis (Becker muscular dystrophy)
  • Muscle disease that involves inflammation and a skin rash (dermatomyositis)
  • Group of inherited disorders that cause muscle weakness and loss of muscle tissue (muscular dystrophy)

POISONING

OTHER

Home Care

Follow the treatment your health care provider recommends to treat the cause of the weakness.

When to Contact a Medical Professional

Call your provider if you have:

  • Sudden weakness, especially if it is in one area and does not occur with other symptoms, such as fever
  • Sudden weakness after being ill with a virus
  • Weakness that does not go away and has no cause you can explain
  • Weakness in one area of the body

What to Expect at Your Office Visit

The provider will do a physical exam. Your provider will also ask you about your weakness, such as when it began, how long it has lasted, and whether you have it all the time or only at certain times. You may also be asked about medicines you take or if you have been ill recently.

The provider may pay close attention to your heart, lungs, and thyroid gland. The exam will focus on the nerves and muscles if the weakness is only in one area.

You may have blood or urine tests. Imaging tests such as x-ray or ultrasound may also be ordered.

Alternative Names

Lack of strength; Muscle weakness

References

Fearon C, Murray B, Mitsumoto H. Disorders of upper and lower motor neurons. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 98.

Selcen D. Muscle diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 421.

Review Date 6/28/2018

Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.