Sucking lips

[MoRaw]

For the past year, my son has continuously sucked on his bottom lip. He does it throughout the day and even while he sleeps.

We have tried everything; from ignoring to scolding him but to no avail.

I worry that he will do permanent damage to his lip. They seem to be getting more swollen.

Any ideas on how to stop this behaviour or understand why he is doing it?

From what I can observe, he does it when he is playing, when he is distressed, etc. There seems to be no specific reason that I can discern.

At wits end now.

Howith old is he? My step son does it with his top lip which is now horrifically chapped. I just keep saying stop when i see it - no point getting cross if it's subconscious though as he can help it just need to break the cycle

He is 2 years and 5 months.

He is very young huni. It won't do permanent damage and I would stick to distraction techniques rather than anything else at this stage.