Many parents first notice a lisp when their child starts saying words with an s or z. Instead of “sun,” they might say “thun,” or “zebra” might sound like “thebra.” While lisps are common and often temporary, understanding what causes them can help families decide whether speech therapy is needed.

Let’s explore the types of lisps, their possible causes, and the ways SLPs help correct them with gentle, effective strategies.

What Is a Lisp?

A lisp is a speech pattern where certain sounds—most often s and z—are produced incorrectly because of tongue placement. The sound may come out distorted, slushy, or replaced with a “th” sound.

Lisps are classified as articulation errors, meaning they occur when the mouth and tongue don’t coordinate exactly as needed for clear speech.

For many children, a mild lisp is part of normal speech development. However, if it continues past early childhood, an evaluation from a speech-language pathologist (SLP) can help determine whether therapy is appropriate.

The Four Main Types of Lisps

Not all lisps sound the same. Each type involves slightly different tongue positions and sound patterns.

1. Interdental Lisp

This is the most common type. The tongue pushes between the front teeth, making s and z sound like th. For example, “sun” becomes “thun.”

2. Dentalized Lisp

Here, the tongue touches the back of the front teeth instead of staying behind them. The result is a muffled or “slushy” s sound.

3. Lateral Lisp

In this type, air escapes from the sides of the tongue, creating a “wet” or “gurgly” sound. Lateral lisps are not part of normal development and almost always need speech therapy to correct.

4. Palatal Lisp

This occurs when the tongue makes contact with the soft palate (the roof of the mouth) instead of the front teeth area. The result sounds more like a “sh” than an “s.”

Understanding which type of lisp is present helps an SLP design the right therapy approach.

What Causes a Lisp?

There isn’t one single cause of a lisp—it can stem from a mix of developmental, physical, and behavioral factors. Some of the most common include:

• Normal developmental patterns: Many children under four or five have a temporary interdental lisp as they learn to coordinate their tongue and teeth.

• Oral habits: Thumb sucking, pacifier use, or prolonged bottle feeding can influence tongue posture and muscle patterns.

• Tongue thrust: A swallowing pattern where the tongue pushes forward may affect speech sounds too.

• Dental alignment: Missing teeth, overbites, or other dental issues can interfere with correct tongue placement.

• Hearing differences: If a child can’t hear certain high-frequency sounds clearly, they may not produce them accurately.

• Muscle tone or motor coordination: Weakness or incoordination in oral muscles can impact precise articulation.

Sometimes, no clear cause is found—and that’s okay. What matters most is how the speech pattern affects communication and confidence.

When to Seek Help from an SLP

It’s normal for preschoolers to have a slight lisp as they learn speech sounds, but most children outgrow it by around age five. If the lisp continues beyond kindergarten, or if it makes your child hard to understand, a speech-language pathologist can help.

You may want to reach out for an evaluation if:

• The lisp persists after age five or six

• Your child is frustrated when speaking

• The sound error affects social confidence

• Teachers or peers have difficulty understanding them

An SLP can assess how your child produces sounds, look at tongue and jaw movement, and recommend specific therapy goals.

How Speech Therapy Helps Correct a Lisp

Speech therapy for lisps focuses on awareness, placement, and practice. Most sessions include fun, motivating activities that encourage correct tongue movement and airflow.

Here’s how therapy typically works:

1. Awareness: The SLP helps the child notice what their tongue is doing when saying s and z.

2. Correct placement: Using mirrors, visuals, and verbal cues, the SLP teaches where the tongue should go (behind the top teeth, not between them).

3. Sound practice: The child practices isolated sounds, then syllables, words, sentences, and finally conversation.

4. Carryover: Once correct production becomes natural, the SLP helps the child use their new speech skills everywhere—home, school, and play.

Progress varies, but with consistent practice and positive reinforcement, most children make steady improvement.

Can Adults Have Lisps Too?

Yes! Some adults continue to have a lisp from childhood, while others develop one later due to dental changes or tongue habits. The good news is that it’s never too late for speech therapy. Many adults see improvement within weeks once they understand tongue placement and commit to daily practice.

Tips for Supporting Clear Speech at Home

Parents and caregivers can help reinforce therapy goals with simple, supportive habits:

• Be patient: Avoid overcorrecting. Instead, model clear s and z sounds naturally.

• Use mirrors: Let your child watch how their tongue moves during speech play.

• Read and repeat: Pick picture books with lots of s words and take turns saying them clearly.

• Celebrate small wins: Every improvement builds confidence and motivation.

These daily interactions make speech practice feel fun and rewarding.

FAQs

Is a lisp always a problem?
Not necessarily. Some mild lisps are developmental and fade naturally. Persistent lisps, however, benefit from evaluation and therapy.

At what age should a child stop having a lisp?
Most children master s and z by age five or six. If the lisp continues past that, it’s best to consult an SLP.

Can a lisp come back after therapy?
Rarely. Once correct tongue placement becomes automatic, the lisp usually doesn’t return—especially with continued awareness and confidence in speech.