My 3-year-old son bites his lower lip during the day and while he's asleep. When I try to make him stop, he does it again. Should I be concerned?
Lip biting might be a coping mechanism that your kid uses to self sooth and make himself feel better.
There could be something medical at play with that I recommend you discuss with your pediatrician. For instance, there could be misalignment of the teeth and jaw that would be best discussed with a dentist. Your son could be allergic to certain foods that make his lips uncomfortable. For instance, my sister is mildly allergic to kiwis and they make her lips itch.
My two cents is that if your son isn't hurting himself, like biting himself until he bleeds for instance, I'm not very concerned (I'm not a doctor and this isn't medical advice). But as always it's best to bring up your concerns with your son's pediatrician and they'll be able to properly evaluate.