Understanding Lisps: What They Are, When They’re Typical, and When to Seek Support

DisclaimerThis blog is intended for educational purposes only and does not replace individualized medical or professional advice. If you have concerns about speech, please consult a licensed speech-language pathologist. This content is not intended to diagnose or provide individualized treatment recommendations.

We often hear the same question from parents and adults alike: “Is this lisp something to worry about?” Lisps are one of the most commonly noticed speech differences, and they can bring up uncertainty, concern, or even self-consciousness—especially when speech matters at school, work, or in social settings.

The goal of this post is to offer clear, reassuring information about what a lisp is, the different types of lisps, and when a speech evaluation may be helpful. Whether you’re a parent, caregiver, teacher, or adult noticing speech differences in yourself, you’re not alone in asking these questions.

What Is a Lisp?

A lisp is a speech pattern that affects how certain sounds—most often /s/ and /z/—are produced. Instead of sounding crisp or clear, these sounds may come out distorted or different than expected.

From an SLP perspective, a lisp is considered a type of speech sound disorder when it impacts clarity, confidence, or functional communication. However, not all lisps automatically require intervention. Some can be part of typical speech development, while others may benefit from speech therapy support.

Common Types of Lisps

Not all lisps sound the same. Understanding the differences can help clarify what you may be noticing.

Frontal (Interdental) Lisp

A frontal lisp, also called an interdental lisp, happens when the tongue comes forward between the teeth during speech. This often makes /s/ and /z/ sound more like “th.”

• “sun” may sound like “thun”

• This type of lisp is common in young children and may be part of typical development

Lateral Lisp

A lateral lisp occurs when air escapes over the sides of the tongue rather than flowing straight out of the mouth. This can give speech a “slushy” or wet sound.

• Lateral lisps are not typically part of normal development

• They often benefit from evaluation by a speech-language pathologist

Dentalized Lisp

A dentalized lisp happens when the tongue pushes against the teeth (rather than between them), slightly distorting the sound.

• Speech may sound imprecise or muffled

• This type can be subtle but still noticeable, especially in older children or adults

When a Lisp Can Be Part of Typical Speech Development

As speech-language pathologists, we want to normalize that speech develops over time. Many young children experiment with tongue placement as they learn new sounds.

• A frontal/interdental lisp can be typical in early childhood

• Some children naturally refine their speech as oral motor control and awareness develop

What matters most is age, consistency, and impact. A lisp that is decreasing over time and not affecting communication may simply need monitoring rather than immediate intervention.

Signs a Lisp May Benefit From a Speech Evaluation

While some lisps resolve naturally, others may benefit from professional support. A speech evaluation can help determine whether intervention is recommended.

You may want to consider an evaluation if:

• A lisp persists beyond early childhood

• Speech is difficult for unfamiliar listeners to understand

• The child or adult feels frustrated or self-conscious about speech

• A lateral lisp is present

• Speech differences impact school participation, social interaction, or work performance

Common Myths About Lisps

“They’ll just grow out of it”

Some lisps do improve with time, but not all do. A speech-language pathologist can help determine whether monitoring or support is appropriate.

“It’s caused by laziness or bad habits”

Lisps are not about effort. They’re about coordination and awareness, which can be supported through therapy when needed.

“Speech therapy is only for kids”

Adults can absolutely benefit from speech therapy, especially if a lisp affects confidence or professional communication.

How Speech-Language Pathologists Support Lisps

Speech-language pathologists are trained to evaluate and support speech sound development across the lifespan. During an evaluation, we look at how sounds are produced, how consistent patterns are, and how speech differences affect daily communication.

Support for lisps in therapy may include:

• Increasing awareness of tongue placement and airflow

• Practicing sounds in meaningful, functional contexts

• Building confidence alongside clarity

• Adapting strategies to the individual’s learning style

Why a Speech-Language Pathologist Is the Right Resource

Speech-language pathologists are experts in speech sound development.

If you’re unsure whether a lisp is typical or something that may benefit from treatment, a Speech Pathologist can help!