Lip problems after Botox: lip flip gone wrong, asymmetry

The lips are surrounded by a ring-shaped muscle, the orbicularis oris, which lets you close your mouth, purse your lips, drink or whistle. A small dose of botulinum toxin is sometimes injected into it to make the upper lip turn out slightly, a technique called a "lip flip", or to soften fine lines around the mouth. This page is part of our atlas of problems after an injection, organised area by area.

What problems can affect the lips?

Two situations are presented: an overdone lip flip, when the upper lip is more relaxed than intended, and uneven lips, when one side moves less than the other. Each has its own page, which details what is known about its cause, when it appears and how long it lasts.

These situations are poorly documented. The area around the mouth is among the areas covered by an expert consensus published in 2004¹, but the official labels do not describe it, since it is not an approved indication, and we have not found a reliable source giving figures for its adverse effects. What is known in general applies: the effect of the toxin is temporary and wears off as the nerve terminals recover³.

Which signs mean you should see a doctor quickly?

A lip that is a little too relaxed or slightly uneven is bothersome but not dangerous. See a doctor promptly if you have trouble keeping liquids in your mouth, eating or speaking clearly. Warm, painful redness spreading from an injection point may be a sign of local infection, which is among the possible reactions³.

Any difficulty swallowing, speaking or breathing means calling emergency services (15 or 112 in France, or your local emergency number): the labels describe these as the rare signs of the toxin spreading away from the injection site^3,4.

Before seeing a doctor, write down the date of the injection and the day the problem appeared, and if possible contact the doctor who performed the injection.

Why are the lips injected?

By slightly relaxing the part of the orbicularis along the edge of the upper lip, the lip flip aims to make the lip turn out a little more, without any filler. No French label provides for this indication: type A toxins have aesthetic indications limited to frown lines, crow’s feet and forehead lines, depending on the product^2,4, and the short-acting botulinum toxin (serotype E) to frown lines only³, approved as of 9 October 2026 in the European Union and Canada^5,6. It is therefore an off-label use, to be discussed with your doctor. To understand why and how the lips can be treated, see the page for this area in our atlas of treatment areas.

The lips are part of the smile: if your problem mainly affects the way you smile, see the page on the asymmetric or changed smile; if it concerns the lower face, the page on the chin after an injection.