What causes muscle stiffness? 15 possible conditions

What Is Muscle Stiffness?

Muscle stiffness is a condition in which muscles feel tight and contracted rather than the usual supple state of muscles at rest. It’s also called stiff muscles, rigidity, and in severe cases, spasticity.

Muscle stiffness is a feeling of tension and contraction in the muscles. In other words, your muscles feel like they are always flexed.  This stiffness may limit your normal range of motion. Sometimes muscles feel stiff after periods of vigorous use like athletic activities, physical labor, or weight lifting.

Other times, muscles feel stiff after periods of inactivity, like rising out of bed in the morning or getting out of a chair from a sitting position. Sometimes, rigid muscles may be due to:

  • muscle spasm caused by overuse
  • injury
  • bleeding into the muscle
  • toxic effect from a bite or sting
  • infection
  • environmental exposure, like extreme heat or cold

Stiff muscles are often a temporary symptom and can be resolved by stretching and movement. However, in other cases, the symptom can be a sign of something more serious.

Possible Underlying Causes of Muscle Stiffness

There are many things that can cause stiff muscles. Usually, if it’s something more than overuse or stiffness from lack of use, there will be other accompanying symptoms. Your doctor will use these symptoms to help determine what’s causing your stiff muscles.

It could be one of the following conditions:

  • acute HIV infection
  • rhabdomyolysis (a condition that breaks down your muscles)
  • overuse syndromes
  • coccidiomyocosis (also known as valley fever or California fever)
  • dermatomyositis (a disease of the connective tissues)
  • generalized anxiety disorder
  • Huntington’s disease (a brain disorder that leads to mental and muscular decline)
  • infectious mononucleosis (also known as “mono”)
  • Legionnaires’ disease (a pneumonia caused by bacteria)
  • muscular dystrophies (a group of diseases that weaken the muscular system)
  • Parkinson’s disease (a nervous system disorder that worsens over time)
  • polio (potentially fatal infectious disease)
  • sprains and strains
  • polymyalgia rheumatica (inflammatory disorder in older adults)
  • hypothermia (the body’s response to severe cold)
  • heat illness
  • post-anesthesia
  • black widow spider bite

Treating Stiff Muscles

If the cause is known and deemed to be minor, such as muscle stiffness from exercise, then rest, massage, and cold or heat packs may be helpful. Stretching and toning muscles are important for keeping muscles flexible and preventing stiffness. Regular exercise to improve circulation and reduce inflammation, along with warm baths and massage therapy, can help decrease muscle stiffness. Observe good posture and check the ergonomics of furniture and equipment used at home and at work.

However, if you don’t know what’s causing your stiffness, make an appointment with your doctor. Your doctor will ask about your medical history and any other symptoms you are experiencing. They may run blood tests and take images of your body using a CT scan or MRI.

Once the cause of your stiffness is determined, treatment options can be explored. Because there are many possible causes of stiffness, treatments vary widely. 

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See a list of possible causes in order from the most common to the least.


Muscular Dystrophies

Muscular dystrophies are a group of diseases that cause damage and weakness to muscles over time. This damage and weakness is caused by the lack of a protein called dystrophin, which is necessary for normal muscl...

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Sprains & Strains

Sprains and strains are injuries to the body, often resulting from physical activity. These injuries are common and can range from minor to severe, depending on the incident. Most don't require medical attention.

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Poliomyelitis, or polio, is a highly contagious disease that is caused by a virus that attacks the body's nervous system. It is most likely to be contracted by children under five years old.

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Infectious Mononucleosis

Infectious mononucleosis, or "mono," is a group of symptoms caused by the Epstein-Barr virus. One potential symptom is a pink rash that looks like the measles.

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Polymyalgia Rheumatica

Polymyalgia rheumatica is an inflammatory disorder that causes pain and stiffness in various parts of the body, including the shoulders, neck, arms, thighs, and hips. The cause of this disorder is unknown.

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Huntington's Disease

Huntington's disease is a hereditary condition in which the brain's nerve cells gradually break down. This affects physical movements, emotions, and cognitive abilities. There is no cure, but there are ways to cope wit...

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Parkinson's Disease

Parkinson's disease (PD) is a progressive neurological disorder. It first presents with problems of movement. Smooth and coordinated muscle movements of the body are made possible by a substance in the brain calle...

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Epilepsy Overview

Epilepsy is a neurological condition caused by malfunctioning brain cells that result in seizures. There is no cure for this disorder but episodes can become less frequent.

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Generalized Anxiety Disorder

People who suffer from generalized anxiety disorder, or GAD, worry uncontrollably about common occurrences and situations. The condition may also be called chronic anxiety neurosis.GAD is different than normal feeling...

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Legionnaires' Disease

Legionnaires' disease is a serious type of lung infection, or pneumonia, caused by bacteria. Fever, chills, cough, and head and muscle aches are common symptoms.

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Rhabdomyolysis is breakdown of muscle fibers. Muscle breakdown causes the release of myoglobin into the bloodstream. Myoglobin can cause kidney damage. Symptoms include dark urine, muscle weakness, and fatigue. Abou...

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Krabbe Disease

Krabbe disease is a rare and usually deadly disorder of the nervous system. It is an inherited genetic disease, which means that it is passed down in families. People with Krabbe disease are not able to create enough o...

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Valley Fever (Coccidioidomycosis)

Coccidioidomycosis, also known as valley fever, is a fungal infection that starts in the lungs and can potentially spread to the rest of the body. Fever, chills and sweating are common.

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Encephalopathy is a general term describing a disease that affects the function or structure of your brain. There are many types of encephalopathy and brain disease. Some types are permanent and some are temporary. Som...

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Dermatomyositis is a rare inflammatory disease that can occur when muscles become inflamed. The most apparent symptom is a rash on the face, nails, elbows, or chest that is red or violet.

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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.
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