When should you consult a doctor?
Pain, bleeding, swelling and ulcers may occur due to biting in the inner lip area. As a rule, biting is accidental and is common in children.
It is quite possible to bite the inner lip:
Yes, involuntary lip biting is painful and uncomfortable, but rarely becomes a serious complication and requires special medical intervention (subject to treatment at home). Keep in mind, the lip has many nerve endings and that is why you feel sharp pain with any injury in this area.
When biting the lip, along with pain, other symptoms may appear, namely:
Consult a doctor if the bleeding does not stop after biting your lip.
You should definitely consult a doctor when an infection is detected or if the discomfort persists and the pain worsens.
The patient should be taken to the clinic immediately if the cause of the injury is a serious fall or incident.
https://www.healthline.com/health/bit-inside-of-lip#symptoms