4 doctors weighed in:

What causes that "fat lip" feeling when you get numbed at the dentist?

4 doctors weighed in
2 doctors agree

In brief: Loss of feeling

When a tooth is numbed for treatment, the same nerve that gives feeling to the tooth gives feeling to other structures as well, such as your lip & tongue.
When these other parts are numb they feel fat, ... That is the numbness. All goes away when the numbness wears off. The lip never actually get fat or looks fat, just feels that way.

In brief: Loss of feeling

When a tooth is numbed for treatment, the same nerve that gives feeling to the tooth gives feeling to other structures as well, such as your lip & tongue.
When these other parts are numb they feel fat, ... That is the numbness. All goes away when the numbness wears off. The lip never actually get fat or looks fat, just feels that way.
Dr. Bruce Apfelbaum
Dr. Bruce Apfelbaum
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Dr. William Goldie
Pediatrics - Neurology

In brief: Sensory distortion

Injections of medication at the dentist suppresses function of the nerves that provide sensation.
Sensation gets distorted, and weird feelings can develop. The good effect is to suppress pain, but the bad effect is the suppression of normal sensation. The tone of muscles and skin also is effected so that they can swell up and appear puffy.

In brief: Sensory distortion

Injections of medication at the dentist suppresses function of the nerves that provide sensation.
Sensation gets distorted, and weird feelings can develop. The good effect is to suppress pain, but the bad effect is the suppression of normal sensation. The tone of muscles and skin also is effected so that they can swell up and appear puffy.
Dr. William Goldie
Dr. William Goldie
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