Some children do grow out of a lisp and some do not, and the type of lisp is the best early predictor of which. A frontal lisp, where the tongue pushes forward between the teeth on /s/ and /z/, is common in young children and often resolves. A lateral lisp, where air escapes over the sides of the tongue and produces a wet or slushy sound, is not part of typical development at any age and rarely resolves without help.
After 27 years of pediatric speech therapy, this is one of the two or three questions I am asked most often, usually by a parent who has been told to wait and is not sure how long waiting is supposed to last.
What is the difference between a frontal and a lateral lisp?
A frontal, or interdental, lisp turns /s/ into something closer to “th.” Many typically developing children produce /s/ this way while they still have gaps from missing front teeth, and the sound tends to correct itself as the permanent teeth come in and the tongue learns a more precise placement.
A lateral lisp sounds different in kind, not just degree. Instead of a narrow central groove directing air over the tip of the tongue, the air spills over the sides. The American Speech-Language-Hearing Association describes these distortions as alterations of the sound rather than substitutions, and lateral productions in particular are known to be resistant to change (ASHA, Speech Sound Disorders: Articulation and Phonology).
That resistance is the practical point. Lateral lisps do not generally self-correct, and they tend to become more entrenched with each year of practice.
At what age should a lisp be gone?
The /s/ and /z/ sounds are later-developing, and clinicians generally expect them to be accurate in most children’s speech by around age seven, with some variation depending on the norms used. That is why a frontal lisp in a five-year-old is usually watched rather than treated, and the same pattern in a second grader is usually evaluated.
Three things change the answer:
- A lateral quality. Age is not the deciding factor. A lateral lisp is worth evaluating whenever it is noticed, including in a four-year-old.
- Intelligibility. If teachers, coaches, or unfamiliar adults are asking your child to repeat themselves, the calendar matters less than the daily experience.
- The child’s own awareness. A child who has started avoiding words, volunteering less in class, or noticing that their speech sounds different has already paid a cost that waiting does not reduce.
What else can cause or maintain a lisp?
Several contributors are worth ruling out during an evaluation. A persistent tongue-forward swallowing pattern, sometimes described as an orofacial myofunctional pattern, can keep the tongue in the wrong resting position. Enlarged tonsils, chronic mouth breathing, prolonged thumb sucking or pacifier use, and an open bite or other dental alignment issue can all play a role.
None of these are diagnoses a parent should make at home, and none of them mean therapy will not work. They simply change the plan, and sometimes mean a dentist, orthodontist, or ENT becomes part of the picture alongside speech therapy.
What does an evaluation look like?
In my Vero Beach practice, an evaluation for a suspected lisp is a single appointment. I listen to /s/, /z/, and the related sounds in isolation, in words, in sentences, and in connected conversation, because many children produce a sound correctly in a word list and lose it in running speech. I look at oral structure and function, at how the tongue rests and moves, and at whether the child can imitate a correct production when given a model, which is one of the strongest indicators of how quickly therapy will go.
Parents often want to know who will actually be evaluating your child before they book, which is a fair question in a solo practice where the person who evaluates is the person who treats.
How long does treatment usually take?
A frontal lisp in a motivated school-age child is often among the faster things we treat, sometimes a few months of weekly sessions once the correct placement is established. A lateral lisp generally takes longer, because the child must build a tongue shape they have never used and then replace a habit that has thousands of repetitions behind it.
The variable that moves the timeline most is practice between sessions, and it does not require a curriculum. A few minutes a day, built into something you already do, outperforms a long weekend session. There are simple ways to support clearer sounds at home that fit into a car ride or a bedtime routine.
Frequently asked questions
Is a lisp in a four-year-old normal? A frontal lisp at four is common and often resolves. A lateral lisp at four is not part of typical development and is worth having evaluated rather than waiting on.
Can a lisp be caused by a tongue tie? Restricted tongue movement can affect some sounds, but a lisp by itself is not evidence of a tongue tie, and most children with a lisp do not have one. An evaluation looks at tongue mobility directly rather than assuming either way.
Will braces fix my child’s lisp? Orthodontic work can change the structure the tongue is working against, and it sometimes helps. It does not teach the tongue a new placement, so a lisp that has been practiced for years usually persists after treatment unless it is addressed directly.
Does a lisp affect reading or school performance? A lisp on its own is a speech sound issue rather than a language or literacy one, and most children with a lisp read normally. What it can affect is participation, because children who are self-conscious about their speech often speak less in class.
Should I correct my child every time I hear it? No. Constant correction tends to reduce how much a child talks, which is the opposite of what helps. Model the correct sound naturally in your own speech and save direct practice for the short, structured moments a therapist gives you.
Schedule an evaluation
If you have been told to wait and you are no longer sure that is the right advice, a single evaluation will tell you which kind of lisp you are dealing with and whether waiting makes sense. Contact Vero Speech Therapy to schedule an appointment in Vero Beach.
About the author
Pamela Cerrato, MA, CCC-SLP is a licensed speech-language pathologist with more than 27 years of experience in pediatric speech and language therapy. She holds the Certificate of Clinical Competence from the American Speech-Language-Hearing Association and provides private, one-on-one therapy to families in Vero Beach and throughout Indian River County, Florida.
