Thumb Sucking in Babies: Causes, Effects and How To Stop

| Reviewed By Sarah Schulze, MSN, APRN, CPNP

It is not unusual for babies to use their thumbs as a way of self-soothing. This behavior can aid in soothing them to sleep or calming them during times of crying.

However, it’s normal to want your child to discontinue this habit and to wonder why some babies seem more attached to it than others.

Is thumb-sucking hereditary? The short answer is that thumb-sucking could be hereditary. Recent studies of identical twins versus fraternal twins lend credence to the idea that heredity is an issue since identical twins were more likely to both be thumb suckers than fraternal twins were. 

Whether or not genetics play a role, many parents look for guidance when they are ready for their children to stop using their thumbs to soothe themselves.

Thumb Sucking in Babies

Your baby will find a way to get his thumb in his mouth very early in life. Here’s what you need to know about this common habit.

Is Thumb-Sucking Bad?

Thumb-sucking isn’t inherently bad. It can become a problem when it happens too frequently for too long, especially if your child is getting permanent teeth and still sucking their thumb often.

Past the age of five, many doctors and dentists recommend trying to curb the habit.

Is Thumb-Sucking Genetic?

It’s possible that thumb-sucking is genetic, though more research would need to be done to confirm this theory. Recent studies show a possible genetic component when research on twins was completed.

Thumb-Sucking Causes

Babies are naturals when it comes to rooting and sucking. Sonogram scans have even shown babies sucking their thumbs in the womb.

If a child figures out how to suck their thumb and that it helps calm them, it’s normal for a habit to form. 

When Does Thumb-Sucking Start?

Thumb-sucking can start as early as before your child is born. If you don’t catch pictures of your child sucking his thumb in the womb, just wait until he arrives. The impulse to root is strong and shows up very early.

Benefits of Thumb-Sucking

You will probably notice that thumb-sucking helps your child calm down and may get them to sleep much faster.

It can also help strengthen their jaw muscles, boost immunity, and aid with digestion. Plus, your child enjoys the soothing sensation it offers.

Effects of Thumb-Sucking

The effects of thumb-sucking largely depend on how long and how frequently your child does it. Effects vary depending on both of those factors.

Long-Term Effects of Thumb-Sucking

If your child sucks his thumb for too long, he may develop an overbite or underbite due to the movement of permanent teeth. There can also be pain in the roof of the mouth from contact with the thumb. 

When your child’s teeth and jaw are impacted by thumb-sucking, speech may be impacted and require therapy to correct.

Effects of Thumb-Sucking on Teeth

Long-term thumb-sucking that continues after a child’s permanent teeth start coming in, usually around the age of five, can negatively impact teeth.

Permanent teeth can end up in the wrong place because of thumb-sucking, so it’s important to help your child break the habit before this occurs.

When To Stop Thumb-Sucking

Most dentists and doctors recommend discouraging thumb-sucking once your child reaches the age of four.

Unlike a pacifier, a thumb is always with your child and can’t be taken away, so it’s important to start weaning your child from thumb-sucking before their fourth birthday. That will give you time for setbacks.

A toddler with curly hair sucking her thumb while sitting in her high chair.

Thumb-Sucking vs. Pacifier

Is it better for your child to suck their thumb or use a pacifier? For the most part, it doesn’t matter.

If your child sucks his thumb, it’s always available and not subject to being dropped constantly. While this is a benefit when your child is young, it can make weaning your child off the thumb very difficult.

Pacifiers are supposed to be discontinued by the age of three, two years before thumb-sucking needs to end.

It’s often easier to keep your child from using a pacifier since you can physically take it away. However, my sister used a pacifier until she was six and stashed them where my parents couldn’t take them, so this plan doesn’t always work. 

Medicine for Thumb-Sucking

If you’ve tried conventional methods, you may have to move to medicinal measures to help your child break the thumb-sucking habit.

There are products that taste bitter but are harmless and can be put on your child’s thumb (this one works well). When your child puts the thumb in his mouth, he’ll taste the bitterness and hopefully remember to stop the habit.

However, many kids wash off the medicine, so you will have to be committed to applying it when necessary.

How To Stop Baby From Sucking Thumb

If you need your child to stop sucking his thumb, there are plenty of methods you can try.

Figure Out the Why

Babies tend to suck their thumbs for comfort, but your toddler may be doing it for other reasons.

Comfort may be the main motive, but they may be triggered by certain events that make them stressed and lead to the desire for soothing through thumb-sucking.

Figure out when and why your child is sucking their thumb so you can address the core issue.

Offer Prizes

Also known as bribery, get your kid on board with some positive reinforcement. It may come in the form of gold stars, special treats, or cold-hard cash.

Some kids simply need positive words offered when they are trying to break the habit. Others, like my sister, may require candy.

Hand Blocks

Use mittens, gloves, or finger covers (find them here) to help your child avoid putting fingers in his mouth. They can easily be taken off, but they are still worth a try.


Look for a safe, natural medicine that can be used as a deterrent.

Related Questions: 

Is It Okay for Baby To Sleep With Thumb in Mouth?

When your child is under the age of four or five, it’s perfectly okay for them to sleep with their thumb in their mouth. When permanent teeth arrive, this gets a bit tricky.

Keeping a thumb in the mouth all night may cause misalignment with permanent teeth, and this can create future dental problems.

Do Pacifiers Ruin Teeth?

Much like thumb-sucking, pacifier use is discouraged at a certain age. After three, you need to convince your child to give up the pacifier in order to avoid dental issues. Before that, it’s a normal habit that may assist with soothing and sleeping.

Extended thumb sucking can alter the way adult teeth come in or even the way your child swallows, speaks, or chews, which can all affect adult teeth.

Talk to your child’s dentist or a speech-language pathologist for advice on extended thumb sucking and its consequences. 

Final Thoughts

Don’t feel discouraged if your child’s soothing method involves thumb-sucking. Know when to help him move past this habit and why it happens in the first place.