Stuttering

What it is

A neurodevelopmental difference in speech fluency, with repetitions, prolongations, and blocks. Nervousness does not cause it.

Common experiences

Stuttering can change from one situation to another, and phone calls are usually harder. Some people swap or avoid words that are hard to say.

What helps

Give time, do not finish sentences, and keep natural eye contact. Speech-language pathologists offer individualized support.

Across life

It begins in early childhood. About 5 to 8 percent of children stutter at some point (ASHA), and most recover. About 1 percent of people stutter long-term (Stuttering Foundation).

Evaluation and treatment

Speech-language pathologists assess stuttering and offer treatment. Stuttering that has lasted 6 to 12 months or more is a risk factor for persisting (ASHA), so ask for an evaluation if it lasts that long or you are worried.

Myth vs fact

Myth: stuttering is caused by nervousness, or you can help by saying slow down or take a breath. Fact: nervousness does not cause stuttering, though stress can make it worse. Genetics and differences in how the brain processes speech are involved, and that kind of advice makes people self-conscious (Stuttering Foundation; NIDCD).

Full chapter

Definitions and terminology

Stuttering, called stammering in the UK and some other countries, is a difference in the flow of speech. The American Speech-Language-Hearing Association (ASHA) describes its core behaviors as repetitions of sounds, syllables, and one-syllable words, prolongations of sounds, and blocks (ASHA Practice Portal). Stuttering that begins in early childhood is called developmental stuttering, and the NIDCD describes it as occurring when a child's speech and language abilities cannot meet the child's verbal demands (NIDCD). Stuttering that begins later in life has its own section below.

How the DSM-5-TR and ICD-11 describe it

The DSM-5-TR calls it childhood-onset fluency disorder (stuttering) and places it among the communication disorders in the neurodevelopmental group. Its criteria describe disturbances in the normal fluency and time patterning of speech that are inappropriate for the person's age and language skills and that persist over time, with frequent and marked occurrences of features such as sound and syllable repetitions, sound prolongations, broken words (pauses within a word), audible or silent blocking, word substitutions to avoid problem words, words produced with excess physical tension, and repetitions of whole one-syllable words. The disturbance must cause anxiety about speaking or limit communication, social participation, or school or work performance, so a diagnosis reflects impact as well as speech patterns. It must begin in the early developmental period and must not be attributable to a speech-motor or sensory deficit, to dysfluency associated with a neurological injury such as stroke, tumor, or trauma, or to another medical condition, and must not be better explained by another mental disorder. Later-onset cases are classified separately, as adult-onset fluency disorder. The ICD-11 calls it developmental speech fluency disorder (6A01.1) and describes a frequent or pervasive disruption of the normal rhythmic flow and rate of speech, with repetitions, prolongations, blocking, and word avoidance. Its entry lists tic disorders as an exclusion, and its inclusion terms cover both persistent developmental stuttering and developmental-onset cluttering.

What stuttering looks like

ASHA lists repetitions, prolongations, and blocks as core behaviors, and head nodding or leg tapping, eye blinking or jaw tightening, and throat clearing as examples of secondary behaviors (ASHA Practice Portal). The NIDCD gives rapid eye blinks and lip tremors as examples of struggle behaviors (NIDCD). The ICD-11 includes word avoidance and the DSM-5-TR includes word substitutions to avoid problem words, so a person may swap or skip a word that feels hard to say, and listeners may not notice the stuttering that was avoided. ASHA includes minimizing avoidances among the aims of treatment. Stuttering can also differ from one situation to another, and the Stuttering Foundation notes that people who stutter usually have more trouble controlling their speech on the telephone.

How common it is

Figures differ between sources and measure different things. The NIDCD says roughly 3 million Americans stutter and that about 5 to 10 percent of children stutter for some period. ASHA reports a cumulative incidence (the share of people who stutter at some point) of 5 to 8 percent, and a rate of 0.78 percent among adults aged 21 to 50. The Stuttering Foundation says about 5 percent of children go through a period of stuttering that lasts six months or more, and that more than 80 million people worldwide stutter, which is about 1 percent of the population. The sources also give different sex ratios: the NIDCD says boys are 2 to 3 times as likely as girls to stutter, and the Stuttering Foundation says it affects four times as many males as females. Treat all of these as approximate. Girls and women stutter too.

When it starts and who recovers

Developmental stuttering begins in early childhood, while speech and language are still developing. The NIDCD says about 75 percent of children who stutter recover and about 25 percent continue into adulthood. The Stuttering Foundation says that of the roughly 5 percent of children who stutter for six months or more, three-quarters recover by late childhood, leaving about 1 percent with a long-term problem. ASHA reports that about 88 to 91 percent recover spontaneously. The estimates differ, but all three sources agree that most children who stutter recover and that some do not. ASHA lists these risk factors for persistence: being male, a family history of persistent stuttering, stuttering that has lasted 6 to 12 months or more, onset at age 3 and a half or later, and slower language development or another speech or language impairment. Risk factors raise the odds and do not decide the outcome for an individual child, so an assessment by a speech-language pathologist is the way to find out what applies to a particular child.

What causes stuttering

No one knows the exact causes of stuttering (Stuttering Foundation). The NIDCD says genetic factors contribute and that four genes have been associated with stuttering. The Stuttering Foundation lists four factors most likely to contribute: genetics (approximately 60 percent of people who stutter have a family member who does); child development (children with other speech and language problems or developmental delays are more likely to stutter); neurophysiology (recent neurological research has shown that people who stutter process speech and language slightly differently than those who do not); and family dynamics, which it describes in terms of high expectations and fast-paced lifestyles. It also says there is no reason to believe that emotional trauma causes stuttering. You cannot catch stuttering from another person, and tickling does not cause it (Stuttering Foundation).

Myths and misunderstandings

Myth: stuttering is a sign of low intelligence. Fact: the Stuttering Foundation says there is no link whatsoever between stuttering and intelligence. Myth: people who stutter are nervous, anxious, or shy. Fact: nervousness does not cause stuttering, and people who stutter should not be assumed to be nervous, anxious, or shy. Myth: you can catch stuttering from someone. Fact: you cannot. Myth: stress or emotional trauma causes stuttering. Fact: stress is not the cause but can aggravate stuttering, and there is no reason to believe emotional trauma causes it. Myth: tickling a child causes stuttering. Fact: it does not. Myth: telling someone to slow down or take a deep breath helps. Fact: advice like this makes people self-conscious (Stuttering Foundation). No one knows the exact causes of stuttering, although genetics and differences in how the brain processes speech are involved (Stuttering Foundation; NIDCD).

Emotions, anxiety, and wellbeing

The DSM-5-TR criteria include anxiety about speaking as one way stuttering can affect a person, and ASHA lists the emotional and cognitive impact of stuttering among the things an assessment looks at. ASHA also lists social anxiety disorder among the conditions that can occur alongside stuttering. The NIDCD says stuttering often affects quality of life and that therapy addresses anxiety in certain speaking situations. The Stuttering Foundation says children and adults who stutter are no more likely to have psychological or emotional problems than those who do not, and that nervousness does not cause stuttering. Taken together, these sources suggest that anxiety about speaking can be part of the experience for some people and can be addressed in therapy, but that stuttering is not caused by anxiety and that people who stutter should not be assumed to be anxious. Stress can aggravate stuttering without causing it (Stuttering Foundation). If you are struggling emotionally, the Crisis help page lists where to turn.

Other conditions that can occur with stuttering

ASHA lists several conditions that can occur alongside stuttering: ADHD, autism spectrum disorder, intellectual disability, language and learning disabilities, seizure disorders, social anxiety disorder, and speech sound disorders. The Stuttering Foundation likewise says children with other speech and language problems or developmental delays are more likely to stutter. Having one of these conditions does not mean a person will stutter, and stuttering does not mean a person has one, but a thorough assessment can check for them. Because the ICD-11 lists tic disorders as an exclusion for this diagnosis, a clinician needs to tell speech interruptions caused by tics from stuttering; the Tourette syndrome and tics guide covers tics. The ADHD, autism, developmental language disorder, and intellectual and developmental disabilities guides cover several conditions on ASHA's list.

Stuttering that starts in adulthood

Stuttering that begins in adulthood is described differently from developmental stuttering. The DSM-5-TR requires onset in the early developmental period for childhood-onset fluency disorder, classifies later-onset cases as adult-onset fluency disorder, and sets aside dysfluency associated with a neurological injury such as stroke, tumor, or trauma. The NIDCD describes neurogenic stuttering as resulting from the brain having difficulty coordinating the different regions involved in speaking. A new change in speech in an adult should be checked by a doctor, who can look for medical causes, and a speech-language pathologist can assess the speech itself. The CDC lists sudden confusion, trouble speaking, or difficulty understanding speech among the signs of stroke and says to call 9-1-1 right away if you or someone else has any of the signs. Outside the United States, call your local emergency number.

Getting evaluated

A speech-language pathologist (speech and language therapist in the UK) carries out the assessment. ASHA's assessment components include a case history, consultation with the family, analysis of a speech sample, how often disfluencies occur and what types and durations they have, secondary behaviors, and the emotional and cognitive impact of stuttering (ASHA Practice Portal). For a child, ASHA lists stuttering that has lasted 6 to 12 months or more as a risk factor for persistence, and the Stuttering Foundation says about 5 percent of children stutter for six months or more, so a child who has stuttered for several months is a good reason to ask for an assessment. The Stuttering Foundation advises parents to contact the school speech-language pathologist. Adults can also seek an assessment and support. Rules about referral, who can diagnose, and funding vary by country, so check locally.

Treatment for preschool children

ASHA describes three kinds of preschool treatment. Indirect treatment focuses on counseling families about changing their own speech and their child's environment. Direct treatment focuses on changing the child's speech, attitudes, and beliefs in order to manage stuttering or help fluency. Operant treatment, such as the Lidcombe Program, uses principles of operant conditioning, with a response contingency that reinforces fluent speech and redirects disfluent speech (ASHA Practice Portal). The NIDCD lists early intervention among the treatment options. A randomized controlled trial of the Lidcombe Program of early stuttering intervention was published in the BMJ (Jones et al., 2005). Whatever approach is used, parents can ask the clinician which approach it is, why it was chosen, how progress will be measured, and what they will be asked to do at home.

Treatment for older children, teens, and adults

ASHA describes treatment for school-age children, adolescents, and adults as individualized and focused on increasing effective and efficient communication, increasing acceptance and openness with stuttering, reducing secondary behaviors and minimizing avoidances, improving social communication, increasing self-confidence and self-efficacy, managing bullying effectively, and minimizing the adverse impact of stuttering. Approaches it describes include speech modification, stuttering modification (such as pull-out, cancellation, and preparatory set), desensitization, cognitive restructuring, self-disclosure, and support groups. The NIDCD lists fluency-technique therapy, electronic devices that alter voice feedback, and self-help groups, and says the U.S. Food and Drug Administration has not approved any drug for stuttering. Because treatment is individualized, it is reasonable to tell the clinician what matters most to you, whether that is smoother speech, less avoidance, or feeling easier in particular situations.

Being a good communication partner

The Stuttering Foundation suggests the following. Listen to the content of what is said, not how it is delivered. Keep natural eye contact and wait. Do not finish the person's sentences. Avoid saying slow down, take a breath, or relax, which it says can be felt as demeaning and is not helpful. Be patient on phone calls, because people who stutter usually have more trouble controlling their speech on the telephone. Speak in an unhurried but natural way yourself. If you are not sure what would help, you can ask the person what they prefer. The Toolkit page has communication cards that show a prepared message in large text and copy it, which can help when words are hard to find.

School, work, and rights

In the United States, speech or language impairment is a named disability category under the IDEA, and its definition names stuttering: a communication disorder, such as stuttering, impaired articulation, a language impairment, or a voice impairment, that adversely affects a child's educational performance (34 C.F.R. 300.8(c)(11)). Section 504 and the ADA can require reasonable accommodations at school and work. In the UK, the Equality Act 2010 can require reasonable adjustments, and in Canada provincial and territorial human rights codes require accommodation to the point of undue hardship. Adjustments people commonly ask for include speech-language services at school, extra time for speaking tasks, alternatives to timed oral presentations, and options other than the telephone for work tasks. These are common requests, not guaranteed entitlements. Laws and eligibility vary, so confirm locally, and see the Resources page, which lists the Job Accommodation Network for workplace guidance.

Identity and being understood

The Stuttering Foundation says stuttering has no link whatsoever with intelligence and that people who stutter should not be assumed to be nervous, anxious, or shy. People relate to their stuttering in different ways. Some want to change how they speak, some focus on speaking openly with their stutter, and many do some of each. ASHA's description of treatment includes acceptance and openness with stuttering, self-disclosure, and support groups, and the NIDCD lists self-help groups. Meeting other people who stutter can reduce isolation, and the Resources page lists the Stuttering Foundation.

For families, teachers, and colleagues

For parents, the Stuttering Foundation advises keeping eye contact, not filling in words, modeling about 2 seconds of wait time, adding pauses to your own speech instead of telling the child to slow down or relax, and praising the child for sharing ideas. It also advises contacting the school speech-language pathologist, and notes that tickling does not cause stuttering. For teachers and colleagues, give the person time, do not finish sentences or fill in words, and do not assume that a person who stutters is nervous, anxious, or shy. Ask privately how the person would like to handle reading aloud, presentations, and phone calls, and offer alternatives where you can.

Sources

American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.).
World Health Organization. International Classification of Diseases, 11th Revision (ICD-11), section on developmental speech fluency disorder (6A01.1).
National Institute on Deafness and Other Communication Disorders. Stuttering. https://www.nidcd.nih.gov/health/stuttering (retrieved October 3, 2026).
American Speech-Language-Hearing Association. Fluency Disorders (Practice Portal). https://www.asha.org/practice-portal/clinical-topics/fluency-disorders/ (retrieved October 3, 2026).
Stuttering Foundation. Frequently asked questions. https://www.stutteringhelp.org/faq (retrieved October 3, 2026).
Stuttering Foundation. Five myths about stuttering. https://www.stutteringhelp.org/five-myths-about-stuttering (retrieved October 3, 2026).
Stuttering Foundation. FAQs for parents. https://www.stutteringhelp.org/faqs-parents (retrieved October 3, 2026).
Stuttering Foundation. 6 tips for speaking with someone who stutters. https://www.stutteringhelp.org/6-tips-speaking-someone-who-stutters (retrieved October 3, 2026).
Jones, M., Onslow, M., Packman, A., Williams, S., Ormond, T., Schwarz, I., & Gebski, V. (2005). Randomised controlled trial of the Lidcombe programme of early stuttering intervention. BMJ, 331(7518), 659. https://doi.org/10.1136/bmj.38520.451840.E0
Centers for Disease Control and Prevention. Signs and symptoms of stroke. https://www.cdc.gov/stroke/signs-symptoms/index.html (retrieved October 3, 2026).
Individuals with Disabilities Education Act regulations, 34 C.F.R. 300.8(c)(11) (speech or language impairment).
Equality Act 2010 (United Kingdom).

Citations are listed so you can verify claims and read further. Guidance is revised over time, so check for newer editions.