Could my crooked smile after Botox be caused by nerve damage? (photo)

Hello,
I would agree with your surgeon that the botox may be affecting the muscles that retract the corner of your mouth. It is possible that the facial nerve was irritated while injecting the botox, but this is very unlikely given how small the needles used for botox injections are. Either way, both of those possibilities should improve with time as the botox wears off or the nerve heals.
-Dr. Halka

It’s very unlikely that your crooked smile is from nerve damage. Botox works by temporarily relaxing muscles, and when a neighboring muscle (like the risorius, which helps pull the corners of the mouth outward) gets affected, it can cause a lopsided or “frozen” smile.
A few key points:
Timing: Botox typically starts working within hours to days, so noticing it the same day isn’t unusual if some spread occurred quickly.
Migration vs. technique: It’s more often due to diffusion or placement rather than true migration weeks later.
Nerve damage signs: Permanent nerve injury is extremely rare with Botox and would usually come with other symptoms like numbness, weakness in unrelated muscles, or pain — not just a temporary asymmetric smile.
Recovery: Effects of Botox gradually wear off over 3–4 months, so your smile should return to normal as the product metabolizes.

Hello, our nurse injector reviewed your case.

The change in your smile is likely due to the Botox spreading slightly to the risorius muscle, which helps pull the corners of the mouth outward when you smile. This should not be nerve damage, and it doesn’t mean there is anything wrong with the nerves or muscles themselves. Rather, Botox temporarily weakens muscle activity, and in this case, the product has likely diffused into a nearby facial muscle unintentionally.

This can sometimes happen when treating TMJ with Botox, especially when injections are near the masseter muscle, which is close to muscles involved in facial expression. The effect is temporary and should gradually wear off as the Botox loses potency over the next few weeks to months. Your natural smile should return as the risorius muscle regains its normal function.

If this happens again or if you're concerned about it, your provider may adjust the placement or dose of Botox in future treatments to avoid affecting nearby muscles.

Thanks for sharing your question and posting your photo. Botox can change the shape of one’s smile. It should not be permanent and will likely resolve when the treatment wears off. Make sure an experienced oculofacial surgeon carefully evaluates your condition in person.
Good luck’

I agree with your Doctor, it probably was a migration to the Risorius muscle, it should recover 100% of the movement after the effect goes away with weeks.

Hello and thank you for the question. After Botox injections, it is possible that the neurotoxin can migrate and effect your smile muscles, which sounds like what you are describing. It would be unlikely to effect the facial nerve with an injection. Botox does not effect nerves themselves, rather it causes a paralysis of muscles by affecting the neruomuscular junction. I would recommend speaking with your initial provider to seek answers about what may have cause the asymmetry you have described.

This is a temporary side effect of Botox which will usually dissipate in 3 - 5 months. The muscle will take some time to go back to its normal strength and movement.

The Botox can cause asymmetry, After 3 months, it should resolve any consequences. Any neurotoxin will be temporary. Your smile should return.

Hi. I love that you asked this question so that I can answer and hopefully have other patients read it and become less worried about their botox injections.
Botox acts at the nerve/muscle junction. It binds to a receptor and stops the nerve from talking to the muscle. It is always temporary. The amount of time the botox protein is bound to the receptor varies from patient to patient but usually lasts 2 to 4 months.
The needles that we use to inject Botox are very small. In order to cause true, permanent nerve damage, you have to CUT through the nerve. That is basically IMPOSSIBLE to do with an injection of Botox.
I agree that the Botox diffused and is affecting one of your smile muscles. It is probably the risorius. Your smile should return to completely normal!!!!

Dear Reserved762856,
you should wait until the effects of Botox go away. It depends on the amount of Botox and the area where it is injected but it usually last for 3-4 months. You should discuss your concerns with your injector.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery