Everything You Needed to Know About Thumb Sucking

Are you a parent with an infant or toddler who sucks their thumb? We here at Dr. Marchbanks’ office are here to answer the questions you either have or SHOULD be asking! 


Most parents understand why children reach for their thumb, but some are new to the world of parenting or otherwise are looking for a refresher on the thumb-sucking phenomenon. 


We want to explain this topic through and through: the why and when, the causes and effects, the ways to address the habit, and—if needed—when to be concerned.  

 Everything you wanted to know about thumb sucking

Let’s begin! 


Why do children suck their thumb?  


Thumb sucking in infants actually starts in the womb. Everyone has seen that adorable ultrasound of the baby curled up with its thumb in his or her mouth, right? Thumb sucking is a tactic for these new-to-the-planet babes to “soothe” themselves. Who can blame them? 


As a child gets older, thumb sucking doesn’t just allude to soothing an anxiety, but can also be done out of boredom. And for some, it turns into a passive habit that can actually cause damage.  


When is thumb sucking the most common?  


Thumb sucking can start from the moment a fetus has a thumb to suck. In extreme cases, the habit can continue on until they are about six years old. Most thumb sucking happens from ages 0-3 months and might persist until the age of four.  


Which brings us to our next point. When do you need to “intervene?” Studies have shown pressuring your child to stop will only give them more anxiety, which will incite more thumb sucking. So, we advise being careful and empathetic when breaking this habit.  


When has it gone on so long that you should be concerned? 


As a parent, we recognize that whatever it takes to stop your kids from crying is will sometimes reign over your longer-term concerns about habit development. So, if the child needs to suck his or her thumb, or pacifier, you’ll usually let ‘em at it without a second thought. 


But, at a certain point, we have to begin to make gentle efforts to sway our little ones out of using their thumbs for a few reasons: 


  • It does start to get socially awkward at school  
  • Physical changes to oral structures, and 
  • A sore thumb and mouth along with other illnesses 


So, how long is too long? Doctors and specialists report that “normal thumb sucking” usually stops around age two. For the little ones who persist, it can last up to age six.  


With this habit it’s crucial as a parent to be observant of the triggers that cause “too-long” thumb sucking to assess when intervention is needed. Thumb sucking in toddlers becomes harmful because: 


  1. Children start to sprout their baby teeth at 4-7 months old. Prolonged thumb sucking at ages three to six can eventually cause physical and aesthetical changes to the placement of teeth and to their bite.


  1. Habitual sucking can cause a thumb to become sore, and can potentially crack and bleed thanks to the constant exposure to saliva. Even thumb nails can crack, and the finger can get infected.


  1. As children start to attend daycares and schooling, as children get older they begin to recognize what thumb sucking is: an agent to combat social anxiety. And, sadly, there are children who will target others for this and perhaps point it out in the not-so-nicest way.


What physical damage can thumb sucking really cause? 


Some of the damage that can be caused by a thumb gone sucked for too long are:  


  1. A protruding upper gum
  2. An overbite
  3. Buckteeth
  4. Gapped teeth
  5. Other malocclusions (deep bites) 


How does it cause that damage?  


The human mouth continues developing until around age 20. Just as the brain is developing, that little mouth is being shaped, literally, by what is put into it. The thumb presses up against the roof of the mouth in children who thumb-suck, and also press against the inside of the upper front teeth as they grow in these formative years.  


Expensive cosmetic corrections later on aren’t anyone’s idea of a good time. So, below are some tips to help you curb your little ones’ thumb-sucking. 


How to break the habit? 


  1. Satisfy the urge to suck.


We recommend starting here, which means starting young. Thumb sucking is evidence of a need—a need for attachment. If not satisfied, thumb sucking becomes a crutch. Fill the need to suck while the baby is young with other toys and options. 


  1. Teach other pacifying behaviors


We’re here to remind you that your baby feels what you feel. So, most importantly, try to keep all of your environments as stress-free and peaceful as possible. There will be plenty of other opportunities in life to learn about stress. If your little one has a strong need for stress-sucking, try using other methods to soothe your child like: rocking, massages, playing animated games, or singing. The earlier your child learns other ways to pacify him or herself, the less s/he will seek the comfort of the breast, bottle, thumb or pacifier.  


  1. Occupy the thumbs


If your child is past infancy, try to keep those thumbs busy. Bored thumbs wind up in the mouth. If you see it about to happen, redirect, distract, and give the child an activity that keeps both of their hands busy. Or, you can suggest a competing habit if they’re old enough like hiding the thumb game, folding their arms, taking the thumb out of the mouth and squeezing it immediately upon it entering the mouth as a corrective behavior. You could even suggest the gold-star reward system, for when they go a whole day without sucking. 


  1. Time your intervention


Ultimately, you want to time your intervention. Assess if the habit is harmful: ferocious sucking, sore thumbs, impending gum and teeth movements—and be gentle. Wait until your son or daughter is in a receptive mood. You wouldn’t want to threaten their independence or make them feel bad! 



We want to offer up one last option: come bring your kids to talk to us! Bringing your little ones into our office from a young age can help them understand the importance of their teeth and how oral habits can affect them, good and bad.  


While some people see thumb sucking as unsightly, or annoying, we see it as a natural evolution into being a healthy adult. At Dr. Marchbanks’ office we’re happy to take some of the parenting questions off your shoulders by providing our professional know-how! 

Also published on Medium.

About Mark C. Marchbanks, D.D.S.

Dr. Mark Marchbanks has practiced dentistry in Arlington Texas since 1983. He enjoys caring for patients young and old. You can find Dr. Marchbanks on
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