Botox frown lines: why, how and for whom?

Frown lines are one of the eleven areas covered by our "why and how" atlas of botulinum toxin. This page explains why they are treated, with which toxins, how quickly and with what risks. It does not replace your doctor’s advice.

Why are frown lines treated?

Frown lines are the vertical creases that deepen between the eyebrows when you frown. They are also called glabellar lines (the glabella is the smooth space between the two eyebrows), or sometimes "11 lines" because of their shape. They are formed by the repeated contraction of two groups of muscles: the corrugators, one on each side, which draw the eyebrows together, and the procerus, in the middle, which pulls them down. The labels describe injection into these very muscles: two points in each corrugator and one point in the procerus¹.

Botulinum toxin temporarily relaxes these muscles. Frowning becomes less marked and the lines deepen less. The effect is not permanent: it fades as the nerve endings recover their function¹.

Horizontal forehead lines and eyebrow position depend on other muscles. They have their own pages, on treating forehead lines and on lifting the eyebrows.

When is the toxin used?

The labels define the indication precisely: the temporary improvement of moderate to severe frown lines at maximum frown, when they have an important psychological impact, in adults^1,2. It is therefore not a routine procedure: how much the lines bother you is part of the indication, and your doctor assesses it with you.

Some situations lead doctors not to treat. The labels contraindicate injection in case of allergy to the toxin or to a component of the product, a generalised disorder of the muscles and of the junction between nerve and muscle (myasthenia gravis, Lambert-Eaton syndrome), or an infection at the injection site^1,2. Pregnancy and breastfeeding are among the situations in which treatment is not recommended^1,2. Injection is not recommended in people with a history of swallowing difficulties^1,2.

Which toxin for frown lines?

In France, frown lines are the only area approved for both families of toxins for aesthetic use^1,2,3. All type A toxins approved for aesthetic use cover this indication^2,4,5,7,8. The short-acting botulinum toxin (serotype E) has been approved in the European Union since 15 July 2026, for this indication only^1,6. As of 29 September 2026, the date of the latest update consulted, it had no entry yet in the French public medicines database³.

Its status depends on the country. It was approved in Canada on 22 June 2026, for the same indication⁹.

The two families do not have the same profile: one works faster and for a shorter time, the other more slowly and for longer. Neither is better than the other, and no trial compares them directly. To understand what sets the new botulinum toxin apart, without ranking the two, see the dedicated page. The long-acting toxin remains the usual choice, in particular when you are looking for an effect lasting several months or for maintenance treatment.

Is it right for me?

No web page can answer this question for you. The points your doctor will assess are well known: how deep the lines are when you frown, how much they bother you, your medical history, your current treatments, any pregnancy plans, and what you expect in terms of how long the effect lasts.

Age matters too, with no simple rule. Several type A toxins are not indicated after 65^4,8, one up to 75⁵. For the short-acting toxin, only 7% of trial patients were 65 or older, and their response rate on day 7 was lower¹.

A few useful questions to ask your doctor: which toxin are you offering me, and why? How long should the effect last in my case? Which side effects should I watch for, and whom should I contact if they occur? When could I consider another session?

Onset and duration

With a type A toxin, first effects usually appear within 2–3 days, up to one week; the peak effect is reached between week 2 and week 4; it usually lasts 3–4 months^2,4,5, up to 6 months depending on the product⁷. Sessions are at least 3 months apart⁴.

With the short-acting toxin, first effects appear from 8 hours, the peak effect is seen around day 7 and it usually lasts 2–3 weeks¹. Its label provides for occasional use. A new injection less than 6 weeks after the previous one has not been evaluated, nor has a type A toxin injected less than 30 days afterwards¹.

For more detail on these timelines, see how long botulinum toxin takes to work.

What are the risks in this area?

For this area, the labels describe drooping of the upper eyelid (eyelid ptosis), drooping of the eyebrow, or conversely an eyebrow arched upwards at its outer end, known as the "Mephisto sign"^1,2. Headaches, eyelid swelling and injection-site reactions (redness, small bruise) are also described². To limit the risk of ptosis, the label asks in particular to avoid injecting near the muscle that lifts the eyelid¹: this is why the eyelid area is approached with caution. These effects are temporary. Published frequencies come from different trials and cannot be used to compare products.

The labels also point out that the effect of the toxin can, rarely, spread beyond the injection site: any difficulty swallowing, speaking or breathing requires immediate medical attention^1,2.

If something unexpected happens, the page on what to do after frown line injections explains how to recognise it and when to see a doctor.