What Causes a Lisp in Children and Adults?

A lisp is a speech sound disorder that most often affects S and Z sounds.

Some lisps fade as a child’s speech develops, especially the early front-of-the-mouth distortions. Others stick around into the school years or adulthood. About 1 in 14 children ages 3 to 17 — roughly 7.2% — had a voice, speech, or language disorder in the past year, and the rate rises to 10.8% for ages 3 to 6.¹

A speech-language pathologist (SLP) can identify the type and cause of a lisp and guide treatment.²

What Causes a Lisp?

Many lisps don’t have a single identifiable cause.²³ Some trace back to how a child learned to make the sound. Others involve physical, sensory, motor, or developmental factors. Common contributors include:

• Learning to say S and Z sounds incorrectly as speech develops
• Jaw alignment issues
• Structural factors such as limited tongue movement, including tongue tie (ankyloglossia)
• Prolonged pacifier use or thumbsucking

A single cause is rarely the whole story. Most children with lisps respond well to speech therapy once the contributing factors are sorted out.³

The Four Types of Lisps

Speech-language pathologists group lisps into four types — frontal, lateral, palatal, and dental — based on where the tongue goes when the sound breaks down.²

1. Frontal lisp — the tongue pushes too far forward, turning S or Z into a “th” sound. This is the most common type.
2. Lateral lisp — air slips over the sides of the tongue, giving S and Z a wet, slushy quality. The sound resembles excess saliva in the mouth.
3. Palatal lisp — the tongue contacts the roof of the mouth while the speaker tries to make an S or Z, distorting the sound.
4. Dental lisp — the tongue presses against the front teeth instead of moving past them. Dental and frontal lisps sound similar.

Identifying the type guides the treatment plan. An SLP will listen carefully and watch tongue placement to make the call.

Symptoms of a Lisp

Lisp symptoms are heard, not felt. The most common signs in a child’s speech include:

• Pronouncing S and Z sounds as “th” (frontal or dental lisp)
• A wet, slushy sound during S and Z (lateral lisp)
• A muffled S or Z that sounds slightly like an “h” (palatal lisp)

Lisps don’t cause physical symptoms beyond speech. But children with lisps sometimes have co-occurring conditions worth checking:

• Structural irregularities in the tongue or palate
• Jaw issues such as an excessive overbite
• Tooth-position issues like an excessive overjet
• A history of repeated ear infections or suspected hearing loss
• Developmental, neurologic, motor, or language concerns that can affect speech

These don’t explain every lisp, but some can shape how an SLP evaluates the speech and what referrals or treatment plan they recommend.³

When to See a Speech-Language Pathologist

See an SLP if your child’s lisp persists around age 5, or sooner if it sounds wet, slushy, or muffled, falls into a lateral or palatal pattern, affects communication, or causes distress. By age 5, most children produce the majority of consonants correctly, though sounds like S, R, Z, SH, CH, and TH can still be developing.⁴⁵

Early frontal or dental distortions sometimes resolve on their own as speech develops. Lateral and palatal lisps are different — they aren’t a typical stage children outgrow and deserve an SLP evaluation rather than a wait-and-see approach.

An SLP will evaluate the lisp, determine its type, and build a treatment plan to correct it. If the cause appears structural — a dental or oral-anatomy issue — the SLP will refer you to a dentist or orthodontist.³

Finding a speech therapist is straightforward. Many public schools employ SLPs who see students during the school day. You can also ask your pediatrician for a referral, check local rehabilitation centers, or contact private therapy clinics.

The American Speech-Language-Hearing Association (ASHA) maintains a search tool for finding a speech therapist near you.

How a Speech Therapist Corrects a Lisp

Speech therapy is effective for most children with articulation lisps. Treatment typically moves through five stages, building from awareness of the lisp to natural conversation.²⁶

Developing Awareness

The first step is teaching a child to hear the difference between their pronunciation and others’. Many children don’t notice their own lisp.

The therapist demonstrates both ways of saying a sound and has the child tell them apart. Parents can practice the same exercise at home.

Learning Tongue Placement

Once the child can hear the lisp, the therapist shows them where the tongue belongs for correct sounds. This usually includes a mirror, hand cues, and direct demonstration.

Tongue-placement drills work well at home too, with the therapist’s instructions as a guide.

Practicing Words

The child practices words that trigger their lisp. For an S problem, the therapist starts with words that begin with S, then moves to S in the middle, then S at the end.

This builds correct production into the muscle memory of everyday vocabulary.

Working on Phrases

The child moves from single words to short phrases that combine difficult sounds. The therapist stays on this step until the child can produce the phrases reliably.

Having Conversations

The final stage is full conversation. The child and therapist talk through topics that pull together everything from earlier steps.

To practice at home, ask your child to:

• Tell you a story about their day
• Teach you how to do something
• Identify pictures or objects around the house

Other Treatments for Lisping

Some non-speech exercises — like drinking through a straw or doing tongue push-ups — are marketed as lisp treatments. Current evidence does not support these techniques for developmental speech sound disorders, either on their own or alongside speech therapy.⁷ Stick with the approach your SLP recommends.

How to Cope With a Lisp

A persistent lisp can affect confidence and social comfort, especially in school-age children.³ Teasing happens, and it can wear on a child’s willingness to speak up in class or with friends.

Adults with lisps face similar pressures in social and professional settings. A few practical strategies help:

• Seek treatment — speech therapy works at any age and builds confidence as the lisp improves.
• Get support — psychotherapy or a counselor can help with the social side, especially for children dealing with teasing.
• Set boundaries — ask friends and family not to mimic or joke about speech differences.

Can a Lisp Cause Other Problems?

A lisp is not physically harmful. Your child’s health is not at risk because of a lisp itself.³

The main effects are social — peer teasing, hesitation to speak, and the confidence dips that follow.³ A lisp can also point to an underlying issue worth checking, such as a tongue tie or jaw alignment problem. An SLP evaluation is the right next step.

Summary

A lisp is a speech sound disorder that most often affects S and Z. Causes vary — some lisps trace to how a child learned the sound, others involve structural factors like jaw alignment or tongue mobility, and many have no single identifiable cause.

Early frontal or dental distortions often resolve as a child’s speech develops. Persistent lisps, and lateral or palatal patterns at any age, deserve an SLP evaluation. Therapy moves through awareness, tongue placement, words, phrases, and conversation — and works well for most children with articulation lisps.