Forehead Botox gone wrong: possible problems and what to do

The forehead is one of the areas most often treated with botulinum toxin, to soften the horizontal lines that appear when you raise your eyebrows. It is also an area where the balance is delicate: the forehead muscle is the only one that lifts the eyebrows. This page is part of our guide to problems after a botulinum toxin injection, organised area by area.

What problems can affect the forehead?

Three situations are specific to the forehead: a frozen forehead, which no longer moves at all; a forehead that looks bulging; and an uneven forehead, more mobile on one side than the other. Two others concern the eyebrows but often follow a forehead injection: the eyebrow raised at the tail, known as the "Mephisto sign" or "Spock brow", and the drooping eyebrow.

The labels confirm these effects. After treatment of the forehead combined with frown lines, one type A toxin reports a drooping eyebrow, a drooping eyelid, the Mephisto sign and headache as common¹. Another product describes, as uncommon, a feeling of heaviness in the forehead, facial asymmetry and a drooping eyebrow². In trials, a drooping eyebrow appeared a median of 5 days after treatment¹.

Each page details the cause, when it appears, how long it lasts and what can help.

Which signs mean you should see a doctor quickly?

A frozen forehead or a raised eyebrow is bothersome but not dangerous: it disappears with the effect of the toxin. On the other hand, see a doctor promptly if the eyebrow or eyelid droops enough to get in the way of your vision, or if your vision is blurred or double^1,2. Any difficulty swallowing, speaking or breathing, even if it seems unrelated to the forehead, 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 site³.

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

Why is the forehead injected?

The frontalis muscle creases the forehead when it lifts the eyebrows. Relaxing it softens the horizontal lines. For this area, only some type A toxins have an aesthetic indication in France^1,2. The short-acting botulinum toxin (serotype E) is approved only for frown lines³: as of 9 October 2026, in the European Union and Canada^4,5. To find out why and how forehead lines are treated, see the page for this area in our atlas of treatment areas.

The forehead is often treated at the same time as the area between the eyebrows: if your problem is located there instead, see the page on frown lines after an injection. If it is mainly your eyebrows that have changed position, the page on eyebrows after an injection covers these situations.