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Smack! Smack! Smack! Hearing this coming from your baby’s mouth can be a little disconcerting.

As a parent or caregiver, you expect your little one to smack their hand on the table or bang their toys, but hearing repeated lip smacking noises may leave you feeling worried.

Rest assured that lip smacking is common and generally not a cause of concern. However, it’s still useful to determine the motivation behind it, so you can understand your little one and their needs better.

Unsure what’s causing your baby’s lip smacking? We’ve compiled a list of some of the more common reasons as well as some rare causes that you’d want to discuss with your child’s pediatrician.

Your baby won’t have the words to tell you that they’re hungry, so you’ll need to rely on other signals to know when they need food.

If your little one is smacking their lips because they’re hungry, you might notice other hunger cues like:

  • rooting or turning their head
  • trying to stick fingers or fists in their mouth
  • clenching their hands into fists
  • crying (though this is a later hunger cue, and hopefully you can avoid it!)

While lip smacking may begin when your little one is hungry, it should diminish once your baby is fed. If it continues after this, there may be another cause.

Lip smacking may be a sign that a tooth is about to poke its way through your little one’s gums. Teething can be uncomfortable, and lip smacking may offer some pain relief.

While teething frequently begins when a baby is 6 to 8 months old, you may notice signs of it as soon as 4 months.

If your little one is teething, you may also notice:

  • increased drooling
  • sore, tender, red, or swollen gums
  • loss of appetite
  • desire to chew

If your child is smacking their lips due to teething, you can offer comfort measures like teething rings to help with any discomfort. In the case of teething, lip smacking will likely diminish once the tooth (or teeth!) cut through the gum line.

Around 4 to 6 months of age, if you notice that your little one is reaching out for your food and smacking their lips while they watch you eat, it may be a sign that they’re getting ready for their own solid foods.

Other signs that your little one is ready for solids include:

  • being able to support their head and body in a seated position
  • picking up finger foods and placing them in their mouth
  • trying to chew

Before beginning solid foods, you may wish to speak with your child’s pediatrician for more guidance and support.

If it’s nearing nap or bedtime and you’ve just finished feeding your baby, you may notice that they continue smacking their lips drowsily. Don’t worry — chances are, they aren’t still hungry. Instead, they may be soothing themselves into a deep sleep.

As they get older, many infants develop self-soothing skills to help them fall asleep and stay asleep. (Another example of this is thumb sucking.)

Some signs that your baby may be sleepy include:

  • eye rubbing
  • ear tugging
  • yawning
  • sucking on a fist or fingers

It’s not uncommon for your baby to smack their lips in deep sleep as well. This can be a sign that they’re soothing themselves through a sleep cycle, dream eating, or starting to get hungry.

If you’re concerned about noises you hear while your baby is sleeping, you may wish to speak with their pediatrician.

Young children love to explore and play using their bodies. As a parent, you may have watched your little one discover their hands and feet. Suddenly, they want to spend hours reaching for them and sticking them in their mouth.

Learning that they can smack their lips is no different. Your little one has a new ability, and it’s fun to repeat it over and over again!

Signs that your child is just enjoying smacking their lips include:

  • having a cheerful attitude as they do it
  • stopping when distracted
  • seeking adult approval and support

While it’s likely that your baby is smacking their lips for one of the above reasons, there are rare cases where it may be a sign of something more serious.

Rare causes of lip smacking include:

  • Gastroesophageal reflux disease (GERD). If you’re noticing other signs of acid reflux like discomfort after feeds and being unable to keep food down, have a discussion with your little one’s pediatrician about whether it could be GERD.
  • Autism spectrum disorder (ASD). Early signs of ASD can include things like poor eye contact, inability to connect with caregivers, a lack of babbling, and continual repetition of behaviors. When repeated lip smacking is seen in combination with other behaviors, it may be beneficial to have a conversation with your child’s doctor.
  • Seizures. Lip smacking is associated with certain types of seizures and can be especially concerning if connected with a zoned-out look. If you believe your child is having a seizure, seek immediate medical help.

You might be surprised the first few times you hear the sound of your baby smacking their lips, but chances are it’s nothing to worry about. Check to make sure that your baby isn’t letting you know that they’re hungry, teething, or otherwise needing your help.

Discuss this behavior with your child’s pediatrician if you have concerns or are unable to identify the cause behind it.