WeaknessLack of strength; Muscle weakness
Weakness is reduced strength in one or more muscles.
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 (MS)
Multiple sclerosis (MS)
Multiple sclerosis (MS) is an autoimmune disease that affects the brain and spinal cord (central nervous system).Read Article Now Book Mark Article
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:
- Adrenal glands not producing enough hormones (Addison disease)
Addison disease is a disorder that occurs when the adrenal glands do not produce enough hormones.Read Article Now Book Mark Article
- Parathyroid glands producing too much parathyroid hormone (hyperparathyroidism)
Hyperparathyroidism is a disorder in which 1 or more of the parathyroid glands in your neck produce too much parathyroid hormone (PTH).Read Article Now Book Mark Article
- Low blood level of sodium or potassium
- Overactive thyroid (thyrotoxicosis)
Hyperthyroidism is a condition in which the thyroid gland makes too much thyroid hormone. The condition is often called overactive thyroid.Read Article Now Book Mark Article
BRAIN/NERVOUS SYSTEM (NEUROLOGIC)
- Disease of the nerve cells in the brain and spinal cord (amyotrophic lateral sclerosis; ALS)
Amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis, or ALS, is a disease of the nerve cells in the brain, brain stem and spinal cord that control voluntary muscle movemen...Read Article Now Book Mark Article
- Weakness of the muscles of the face (Bell palsy)
Bell palsy is a disorder of the nerve that controls movement of the muscles in the face. This nerve is called the facial or seventh cranial nerve. D...Read Article Now Book Mark Article
- Group of disorders involving brain and nervous system functions (cerebral palsy)
Cerebral palsy (CP) is a group of disorders that can involve the brain. This affects nervous system functions, such as movement, learning, hearing, ...Read Article Now Book Mark Article
- Nerve inflammation causing muscle weakness (Guillain-Barré syndrome)
Guillain-Barré syndrome (GBS) is a serious health problem that occurs when the body's defense (immune) system mistakenly attacks part of the peripher...Read Article Now Book Mark Article
- Multiple sclerosis
- Pinched nerve (for example, caused by a slipped disk in the spine)
- Inherited disorder that involves slowly worsening muscle weakness of the legs and pelvis (Becker muscular dystrophy)
Becker muscular dystrophy
Becker muscular dystrophy is an inherited disorder that involves slowly worsening muscle weakness of the legs and pelvis.Read Article Now Book Mark Article
- Muscle disease that involves inflammation and a skin rash (dermatomyositis)
Dermatomyositis is a disease that involves muscle inflammation and a skin rash. Polymyositis is a similar inflammatory condition that also involves ...Read Article Now Book Mark Article
- Group of inherited disorders that cause muscle weakness and loss of muscle tissue (muscular dystrophy)
Muscular dystrophy is a group of inherited disorders that cause muscle weakness and loss of muscle tissue, which get worse over time.Read Article Now Book Mark Article
Botulism is a rare but serious illness caused by Clostridium botulinum bacteria. The bacteria may enter the body through wounds or by eating imprope...Read Article Now Book Mark Article
- Poisoning (insecticides, nerve gas)
Insecticide is a chemical that kills bugs. Insecticide poisoning occurs when someone swallows or breathes in this substance or it is absorbed throug...Read Article Now Book Mark Article
This article describes a group of different conditions caused by eating contaminated fish and seafood. The most common of these are ciguatera poison...Read Article Now Book Mark Article
- Not enough healthy red blood cells (anemia)
Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. Different type...Read Article Now Book Mark Article
- Disorder of the muscles and nerves that control them (myasthenia gravis)
Myasthenia gravis is a neuromuscular disorder. Neuromuscular disorders involve the muscles and the nerves that control them.Read Article Now Book Mark Article
Polio is a viral disease that can affect nerves and can lead to partial or full paralysis. The medical name for polio is poliomyelitis.Read Article Now Book Mark Article
Follow the treatment your health care provider recommends to treat the cause of the weakness.
When to Contact a Medical Professional
Contact 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.
Eyre AJ. Weakness. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 9.
Fearon C, Murray B, Mitsumoto H. Disorders of upper and lower motor neurons. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff's Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 97.
Selcen D. Muscle diseases. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 393.
Review Date: 7/25/2022
Reviewed By: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.