Thumb sucking, regardless of what you hear, is a very normal, natural and healthy activity that your baby can do. Usually, children overcome this habit by the age of three, even if they start, without any physical or psychological side effects.
However, some children are not affected by this habit. If it continues through the ages of 4, 5 and 6, your child may be at risk for or already develop some problems associated with thumb sucking. You can look for the guide on how to stop thumb sucking via https://www.amazon.co.uk/Age-2-7-Stop-Thumb-Sucking/dp/B00VQU2DZS.
How do you get your child to quit thumb sucking?
Do not yell at, peck, or annoy your child if they are still sucking their thumb. This will only strengthen their thumb-sucking habit and make it even harder to break. There are several ways that young children stop sucking their thumbs:
1) Taste – There are products you can put on your child's thumb that taste quite bad. This of course is completely safe and approved by doctors. This is exacerbated by direct stimulation of the thumb with an unpleasant taste of the thumb.
2) Praise – If the child does not suck his thumb for a period of time, be sure to praise him. It provides positive reinforcement for something well done.
3) Pay more attention to the child – thumb sucking often continues because of feelings of insecurity and a need for comfort.
4) Older Children – Help them choose the method they want to try. This gives them more control over braking.