What causes slurred speech?

There are many causes of slurred speech. Disease or injury to the brain or nerves and muscles of the face, tongue, and vocal cords may cause slurred speech.

Neuromuscular causes of slurred speech

Slurred speech can be caused by disease or damage affecting the muscle and nerves of the vocal cords, mouth, or tongue. These neuromuscular causes include:

  • Amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease, severe neuromuscular disease that causes muscle weakness and disability)
  • Bell’s palsy (swollen or inflamed nerve that controls facial muscles)
  • Cerebral palsy (birth defect that causes brain damage that may result in problems with speech or muscular coordination)
  • Multiple sclerosis (disease that affects the brain and spinal cord causing weakness, coordination, balance difficulties, and other problems)
  • Muscular dystrophy (inherited disorder that causes a progressive loss of muscle tissue and muscle weakness)
  • Myasthenia gravis (autoimmune neuromuscular disorder that causes muscle weakness)
  • Parkinson’s disease (brain disorder that impairs movement and coordination)
  • Surgery on the face, head or neck

Other causes of slurred speech

Slurred speech may also be caused by:

  • Alcohol or drug intoxication
  • Dementia
  • Ill-fitting dentures
  • Medication side effects
  • Migraine

Serious or life-threatening causes of slurred speech

In some cases, slurred speech may be a symptom of a serious or life-threatening condition that should be evaluated immediately in an emergency setting. These include:

  • Brain tumor
  • Stroke
  • Transient ischemic attack (temporary stroke-like symptoms that may be a warning sign of an impending stroke)
  • Trauma to the face, head or neck
  • Traumatic brain injury

Questions for diagnosing the cause of slurred speech

To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your slurred speech including:

  • How long have you had slurred speech?
  • Did your slurred speech develop slowly over time or after a single incident?
  • Have you experienced any recent injuries or trauma?
  • Do you have any other symptoms?
  • What medications are you taking?

What are the potential complications of slurred speech?

Because slurred speech can be caused by serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:

  • Brain damage
  • Disability
  • Impaired balance and coordination
  • Loss of vision and blindness
  • Neurological problems, such as memory loss, confusion, and encephalitis
  • Paralysis
  • Permanent hearing loss
  • Permanent loss of sensation
  • Seizures and tremors
  • Unconsciousness and coma


  1. Dysarthria. PubMed Health, a service of the NLM from the NIH. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004947/.
  2. Dysarthria. American Speech-Language-Hearing Association. http://www.asha.org/public/speech/disorders/dysarthria.htm.

What is slurred speech?

Slurred speech is a symptom characterized by poor pronunciation of words, mumbling, or a change in speed or rhythm during talking. The medical term for slurred speech is dysarthria.

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What other symptoms might occur with slurred speech?

Slurred speech may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect your ability to speak may also involve other body systems.

Neurological symptoms that may occur along with slurred speech

Slurred speech may accompany other symptoms affecting the brain and nerves including:

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Aug 8, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Brain and Nerves