Finger-sucking in children – when is this abnormal and how can you manage it?

How common is this phenomenon of finger-sucking in children?

Super common.
Up to 25% of children aged 2 years.
Between 10-15% of children at the age of 5 years.
And of course, in most of the children, it is the thumb.

Why do children suck their fingers to begin with? What stands behind this practice?

Keep in mind that this can start already intrauterine, take a look at the short chapter on this website about sucking blisters that can be seen in newborn babies.
At this young age, the following stands behind this practice:
Rooting reflex – when you touch the angle of a baby’s mouth, they will turn their head and lips to that side in order to try and latch the nipple. This reflex presents at birth and weakens and gradually disappears at the age of 1 month.
Sucking reflex – placing something inside a baby’s mouth, activates the sucking reflex, just like when they feed. This reflex presents at birth and disappears gradually by the age of 4 months. After this age, it turns into a habit because it is soothing and makes them feel safe during certain times of the day or all throughout the day.

What about a child that resumes thumb-sucking after they have already stopped?

This also happens quite often, especially after a stressful event (such as the birth of a younger sibling).

What is the problem with this practice?

Usually, it is not problematic. Nonetheless, two things that may come up are:
Paronychia (an infection in the nail bed) – imagine there is a microscopic injury t the skin, sucking the thumb, whether forcefully or not forcefully, can lead to further trauma and and bacteria from the child’s mouth can cause infection. We have an excellent chapter on this website about paronychia, find out more in the link here.
Changes to the structure of the mouth and teeth – usually it leads to enlarged spacing between the upper and lower teeth in the front of the mouth.

So, at what age is it abnormal for children to suck their fingers?

Generally, there aren’t any medical issues with finger sucking until at least the age of 5 years.
Starting the age of 5, this habit can cause abnormal opening of the mouth and additional changes to the teeth, some of which will need orthodontic treatment at a later stage.

How can finger-sucking be managed?

First of all, in very young children, where this isn’t truly a problem, I do not recommend trying to manage it and I suggest parents try to ignore it. Or in other words, if you would like this habit to disappear, it is better to ignore it and not comment about it. The more you comment about it, the higher the chances of the habit being reinforced.
When the child reaches the right age, you can try to gently shift their attention to other habits or try to give them a prize for being able to avoid sucking their fingers for a certain period of time (the stickers method). But obviously, do not exaggerate with the prizes because within a week’s time you may find yourself handing out cars to them.
When a child resumes finger sucking after a period of time during which they had stopped, it is more important to focus on trying to identify the problem that is causing the child stress and to relieve that stress from them.

What should I avoid doing?

Do not get angry, do not comment about it, do not spank the child’s hand and try to ignore the habit as much as possible.

What about applying a bitter ointment or using certain devices?

There is no evidence that any of these approaches work and I have to say that I would save these techniques for very resistant cases, when there is concern for orthodontic issues and only when a professional has recommended using these techniques.

In summary, we all have different habits, some are good and some are not so good and we would prefer to get rid of them. Finger/thumb-sucking is a habit that does not typically cause any harm to young children, so I think it is worth picking your battles and ignoring this one.