Ask the experts
My 27-month-old son has sucked his thumb since he was a newborn. In the past month, the nail on his thumb has become so soft that it is about to come off, and now he has started sucking his other thumb. What can I do?
You can sit back, relax! Ultrasounds and actual videos of fetuses in the womb show them sucking thumbs or fingers! This is a most natural, normal, self-nurturing, and stress-reducing behavior. A veteran nurse in the newborn nursery at my training hospital (many years ago!) used to actually try to encourage the newborns to "find their thumbs" and felt she helped thousands of parents and tens of thousands of babies get millions of hours of better sleep!
The feeling of pediatricians and dentists alike is that as long as the thumb sucking has ceased by the time the first permanent upper central incisor teeth come through (usually age 7 or so), this behavior does not cause any dental disorders. And even at this age, foul-tasting potions applied to the thumb is cruel and to be avoided. If the behavior has not gone away by this age, I've found that a very reasonably priced appliance that your dentist can apply across the child's upper arch prevents the formation of a suction. The behavior usually quickly ceases, without threats or punishment.
In your toddler's case, he did some very impressive problem-solving all on his own by switching thumbs! Even if the first nail comes off, there will be a perfectly fine new one beneath. And be sure to avoid the use of any kinds of arm restraints or bandages (that could become lodged in his airway!).
There are plenty of things that us parents have to worry about. Thumb sucking is not one of them!
Medically reviewed by Margaret A. Walsh, MD; Board Certification in Pediatrics
"Oral habits and orofacial development in children"