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:
After a stroke
After injury to a nerve
During a flare-up of multiple sclerosis
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 mononucleosis or 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 diseases or conditions affecting many different body systems. Causes may include:
Weakness may be caused by a variety of conditions, including:
Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.