What Is a Lisp?

Medically Reviewed by Dan Brennan, MD on February 18, 2024
4 min read

A lisp is a speech impediment that specifically relates to making the sounds associated with the letters S and Z. Lisps usually develop during childhood and often go away on their own. But some persist and require treatment.

There are no known causes of lisps. Some people think that using a pacifier after a certain age may contribute to lisps. They believe prolonged pacifier use can strengthen the muscles of the tongue and lips, making lisps more likely. However, pacifier usage is not a factor in every child with a lisp. Additionally, each child who uses a pacifier doesn't get a lisp.

Other possible causes of lisps include:

  • Tongue-tie — a condition where the tongue is tethered to the bottom of the mouth. This restricts its movement. Another name for a tongue-tie is ankyloglossia.
  • Problems with jaw alignment.
  • Simply having learned to say the sound incorrectly.

Many young children have some kind of lisp as they learn to talk. It is one of the most common speech impediments. About 23% of speech-language pathologist clients have lisps. 

However, you may want to look into professional help if your child is still lisping after the age of 4 1/2. However, children as young as three years old can work on lisping with a speech-language pathologist.

There are four types of lisps:

  • Frontal lisp. This lisp occurs when you push your tongue too far forward, making a "th" sound when trying to words with S or Z in them.
  • Lateral lisp. Extra air slides over your tongue when making S and Z sounds, making it sound like there is excess saliva.
  • Palatal lisp. You touch your tongue to the roof of your mouth when making S and Z sounds.
  • Dental lisp. This lisp sounds like a frontal lisp. The difference is that instead of pushing the tongue through the teeth, it is pressing against the teeth.

Speech-language pathologists are specialists who can help children with lisps. They will evaluate what type of lisp your child has and then help them with it over a period of time. It can take anywhere from a few months to a few years to get rid of a lisp. If a child is older when they start working with a speech-language pathologist, it may take a longer time. 

Speech pathologists work with people who have lisps to help them recognize what their lisp sounds like and how to position their tongue in the correct place to make the sound. They do this by giving them exercises to do, like saying specific words or phrases with the sounds in them. Once your child has been working on their lisp for a while, your speech pathologist will engage them in conversation to challenge them to remember proper tongue placement.

If your child's lisp is from a tongue-tie, a doctor may recommend a simple in-office procedure called a frenotomy to reduce the tethering. They take a pair of scissors and snip the excess tissue holding the tongue down. If the tongue-tie is more severe, a surgery called a frenuloplasty may be required.

Make sure that any speech-language pathologist you take your child to is licensed. In the US, each state has a different licensure process for speech-language therapists. They may also opt to get an additional certification from ASHA — the American Speech-Language-Hearing Association. Those who have this certification show they meet certain qualifications and follow ASHA's code of ethics. 

You should also make sure the speech-language therapist is child-friendly. You may be able to find this information on their website or by reading reviews online. In the session, you can also observe the interaction to make sure you are comfortable with how the therapist is treating your child.

After evaluation, the speech-language pathologist should be able to tell which type of lisp your child has. They should also be able to recommend exercises specific to that type of lisp to help your child. 

Lisps are just one type of speech impediment. Other common speech impediments include:

  • Lambdacism. Trouble saying the letter L. People with lambdacism often use the R sound as a substitute.
  • Rhotacism. Difficulty with saying the letter R correctly.

The three most common speech impediments are sigmatism (lisping), lambdacism, and rhotacism. However, other people can also have trouble pronouncing the sounds associated with the letters K, G, T, D, and E. 

Whether or not your child sees a speech-language pathologist, there are things you can do at home to help your child's lisp, including:

  • Treat allergies and sinus problems that may lead to lisping.
  • Curb thumb sucking.
  • Have your child drink through a straw to build strength.
  • Encourage playtime with things like bubbles or horns.