Frown lines Botox gone wrong: possible problems and what to do

Frown lines, the vertical creases between the eyebrows, are the area most often treated with botulinum toxin. They are surrounded by sensitive structures: the eyebrows above, the eyelids just below. Possible problems after an injection here therefore mainly affect these neighbours. This page is part of our SOS guide after a botulinum toxin injection, organised area by area.

What problems can follow a frown line injection?

The frown line area has no problem page of its own: possible effects show up on the eyebrows or the eyelids, and each one has its page in the area concerned. They are the drooping eyelid, the drooping eyebrow, the eyebrow raised at the tail (Mephisto sign, or "Spock brow") and uneven eyebrows.

The labels describe these effects. After treatment of frown lines with a type A toxin, a drooping eyelid and headache are common, the Mephisto sign and eyelid swelling uncommon¹. In trials that treated both frown lines and the forehead, a drooping eyelid appeared a median of 9 days after treatment¹. Another product describes, as uncommon, a drooping eyelid or eyebrow, facial asymmetry and a feeling of heaviness in the eyelids or eyebrows³. For the short-acting botulinum toxin (serotype E), the label reports a drooping eyelid in 0.17% of patients, a drooping eyebrow in 0.13% and a Mephisto sign in 0.04%². These frequencies come from different trials and cannot be compared with one another.

Which signs mean you should see a doctor quickly?

A drooping eyelid sometimes gets in the way of your vision, particularly in the evening or when driving: the short-acting toxin label notes a risk of drooping eyelid and visual disturbance that could affect driving². If your vision is impaired, blurred or double, see a doctor promptly³. Any difficulty swallowing, speaking or breathing means calling emergency services (15 or 112 in France, or your local emergency number): these are the rare signs of the toxin spreading away from the injection site².

If possible, contact the doctor who performed the injection first, noting the date of the injection and the day the problem appeared.

Why are frown lines injected?

The crease between the eyebrows is formed by two small muscles, the corrugators, and by the procerus muscle, at the root of the nose: this is where the injections are given². The labels ask doctors to avoid the area near the muscle that lifts the eyelid and, for the short-acting toxin, to place injections in the outer part of the corrugator at least 1 cm above the bony rim of the eye socket². In France, this is the only area approved for both type A toxins and the short-acting toxin^1,2. As of 9 October 2026, the short-acting toxin is approved in the European Union (since 15 July 2026) and in Canada (since 22 June 2026)^4,5. To understand how and why frown lines are treated, see the page for this area in our atlas of treatment areas.

This area is often treated together with the forehead: if your problem is located there instead, see the page on the forehead after an injection. If it is mainly the eyelid that is affected, the page on drooping or puffy eyelids covers these situations.