Lisp in children: types, ages and when to get help

A lisp is when a child says "s" and "z" in an unusual way, so "sun" might sound like "thun" or come out slushy. Some lisps are a normal phase for young children, and some are not. An interdental lisp (tongue between the teeth) is common in some children until about 4 and a half, while a lateral lisp (air escaping over the sides of the tongue) is never part of typical development and is worth having assessed at any age.^[][]

The four types of lisp

Bowen describes four types. The type matters more than the child's age, because two of them are expected in young children and two are not.^[]

If you're not sure which type you're hearing, watch your child's mouth as they say "sun" or "bus". A tongue tip you can see between the teeth points to an interdental lisp. A slushy sound with no tongue showing may be lateral, and a speech pathologist can confirm it.

What's typical at each age

Children learn speech sounds over several years, and "s" usually settles around 4 to 5. Raising Children Network says most children learn "s" at around 4 to 5 years.^[]

• 3 to 5 years. Some preschoolers still produce "s" as "th". Speech Pathology Australia lists this alongside other sounds that are still settling at this age, such as "r", "v" and "th".^[]
• Around 4 and a half. An interdental or dentalised lisp should be resolving. Speech pathologist Caroline Bowen describes waiting well past 4 and a half as poor advice.^[]
• When the front teeth fall out. School-aged children may have trouble with "s" and "z" while they're missing front teeth.^[]
• 8 years. Raising Children Network lists a stutter or lisp at 8 as a sign to see your GP or paediatrician, who may refer you to a speech pathologist.^[]

A lateral or palatal lisp doesn't follow this timeline. It isn't a stage children pass through, so there's no age at which it's expected to fix itself.^[]

When to see a speech pathologist

Book an assessment if any of these apply:

• your child has a lateral (slushy) or palatal lisp, at any age^[]
• an interdental or dentalised lisp is still there past about 4 and a half^[]
• your child is 8 or older and still lisps^[]
• other sounds are also hard to understand, or your child gets frustrated or upset when people don't understand them^[]
• you have any doubt about your child's hearing, or they've had lots of middle ear infections^[]

Speech Pathology Australia suggests a hearing check by an audiologist when parents are worried about how their child says sounds, because children need to hear sounds clearly to learn to say them.^[]

You can go straight to a private speech pathologist, or talk to your GP, paediatrician or child and family health nurse first.^[] If the lisp is one part of a wider pattern of unclear speech, our page on speech sound disorder explains how that's assessed.

What therapy involves

Bowen describes speech pathology for lisps in young children as usually short-term and successful. Most, she says, use a traditional articulation approach, which usually works through steps like these:^[]

1. Checking your child can hear the difference between "s" and "th" (as in "sink" and "think")
2. Saying the "s" sound correctly on its own
3. Adding it to syllables ("sa", "see")
4. Then words ("sun", "bus", "messy")
5. Then phrases and sentences
6. Then everyday conversation
7. Finally, your child noticing and fixing their own "s" without reminders

Bowen notes that brief, frequent practice works best, with an adult supervising. Your speech pathologist will suggest how often to practise at home.^[] The speech pathologist teaches the tongue position and airflow, shows you how to practise at home, and moves to the next step when your child is ready.

Bowen also notes that successful self-help is rarely reported, and that the longer a lisp continues, the stronger the habit becomes.^[] That's the main reason not to wait years once a lisp is past the age when it's typical. More about what sessions look like is on our speech therapy page.

Simple things parents can do

You don't need to drill your child or point out every lisped word. These everyday habits help without making talking feel like a test:

• Model it back. If your child says "Look, a thnake!", reply "Yes, a snake! A long snake." Saying the word correctly with a little emphasis gives them a clear example without correcting them.^[]
• Skip the "say it properly" requests. Raising Children Network notes there's no need to correct young children every time they say a word differently.^[]
• Keep practice short once therapy starts. Short, frequent practice works best. Follow the routine your speech pathologist sets.^[]
• Get hearing checked if you're unsure. Hearing matters for learning to say sounds correctly.^[]
• Let your child talk freely. Give them time to finish, and respond to what they said, not how they said it.

What to do next

If your child is under about 4 and a half with an interdental or dentalised lisp and their other speech is clear, keep modelling and listen again in a few months. A speech pathologist can still check which type it is at any age. If the lisp is slushy, if it's lasted past 4 and a half, or if you're simply not sure which type it is, a speech pathologist can tell you which type it is and whether it needs therapy. For a broader view of where your child's speech should be, see our milestones by age.

To see where "s" fits with other sounds, check our speech sounds by age chart, and if you're looking for help, read how to choose a speech pathologist.

If you'd like to talk it through, you can send Hey Sprout an enquiry.