Weakness is reduced strength in one or more muscles.
Lack of strength; Muscle weakness
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:
BRAIN/NERVOUS SYSTEM (NEUROLOGIC)
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:
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.
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
Reviewed 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.
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