In short: For expression lines, the effect of botulinum toxin usually lasts about three to four months, and longer in some people. First changes often become visible after three to seven days. After about two weeks, the response can already be assessed quite well, although the result may still develop. How long the effect lasts depends on factors such as the treated muscles, the product and the dose. Whether and when another treatment makes sense is therefore discussed individually with your doctor.
Before treatment: what can change?
When you smile, frown or raise your eyebrows, your facial muscles are at work. This creates lines that are mainly visible during movement, known as dynamic wrinkles or expression lines. They include the frown line between the eyebrows, horizontal forehead lines and crow’s feet at the outer corners of the eyes.
Botulinum toxin temporarily weakens the signal from the nerve to the treated muscle. The muscle contracts less strongly, and the expression lines above it can appear less pronounced. The active substance does not fill a wrinkle and does not replace lost tissue.
If a line stays visible when your face is relaxed, it has a static component. Such etched-in lines respond less clearly than pure movement lines. A wrinkle that is still visible therefore does not automatically mean that the treatment is not working or has already worn off.
A realistic assessment includes looking at the face both at rest and in motion. You can read more about the individual areas on our pages on treating the frown line, treating forehead lines and crow’s feet.
The first days: the effect begins
Immediately after the injection, the later effect cannot yet be seen. First changes often appear after three to seven days: for example, the treated area can no longer be tensed as strongly when you frown. How clearly you notice this varies from person to person.
So do not judge the result straight after your appointment, what counts is how it develops. If you want to keep track of the change for yourself, photos taken in similar light, with the same head position and a comparable expression can help. A photo taken while smiling can only be compared to a limited extent with one of a relaxed face.
Redness, swelling, tenderness or bruising can occur at the injection sites. These local reactions are separate from the actual effect on the muscle. Follow your doctor’s instructions and avoid rubbing or massaging the treated areas.
After about two weeks: assessing the result
After about two weeks, the effect has clearly developed in many cases. This is a useful point of reference for discussing the change. It does not mean, however, that every product reaches its maximum effect in every person at exactly that time. The visible smoothing can still develop further.
Several questions matter in the assessment: Has the muscle movement changed? How does the area look at rest? Does the change match the goal you discussed beforehand? If a line remains, it is important to distinguish whether there is still muscle activity or whether the wrinkle is already etched into the skin.
A check-up does not automatically mean a top-up
A medical assessment once the effect has set in is not the same as another injection. Whether a further treatment is an option at all and what interval is needed depends on the findings and on the product used.
If you notice hardly any change or the result looks uneven, contact the practice that treated you. The cause cannot be reliably determined from a single photo or an early look in the mirror.
The following months: the effect wears off
The effect does not end on a fixed day. The signal between nerve and muscle recovers and movement gradually returns, so lines may become more visible again when you frown or smile. Three to four months from the injection are usually taken as a guide, not from the day you first notice a change.
| Time after injection | Typical course | What this means for you |
|---|---|---|
| Immediately afterwards | The effect on the muscle is not yet visible. | The later result cannot be judged yet. |
| Often after three to seven days | First changes become noticeable. | The effect is building up. |
| After about two weeks | The effect has often clearly developed. | An assessment makes sense, further changes are possible. |
| In the following months | Movement gradually returns. | Visible expression again does not immediately mean a complete loss of effect. |
| Usually after about three to four months | The usual duration of effect has been reached. | If you wish, the next steps can be discussed. |
This timeline describes a typical course and is no promise of a specific duration. What you perceive as the end of the effect also plays a role: the first visible movement or the largely complete return to the starting point. These are two different moments.
When is another treatment an option?
Having another treatment is a personal decision, not an obligation. If the effect is wearing off and you are considering a repeat, talk through how it went: the change achieved, any side effects and how much expression you would like to keep.
The prescribed interval for the product used must be observed. The Swiss prescribing information of one product approved for expression lines specifies at least three months between treatments. Movement returning early is therefore no reason to aim for the shortest possible interval.
More active substance is not a general solution for a longer duration either. The dose has to suit the muscles and the treatment goal. Excessive doses or overly frequent injections can increase the risk of neutralising antibodies forming, which can impair the effect.
At Swiss Derma Clinic in Zurich, we treat expression lines with botulinum toxin. There is no fixed number of appointments per year for this. Please bring details of previous treatments, even if they took place at another practice.
When should you seek medical advice?
Before a treatment, tell your doctor about medication, dietary supplements, pre-existing conditions and previous procedures. Conditions involving muscle weakness, known allergies, infections in the area to be treated, and pregnancy or breastfeeding are particularly important. This information can speak against treatment or call for special caution. Do not stop prescribed medication on your own for an aesthetic appointment.
After a treatment, a newly drooping eyelid, visual disturbances or noticeable muscle weakness should be assessed by a doctor promptly. Do not wait for a scheduled check-up. If you have difficulty swallowing, speaking or breathing, you need immediate medical help via the emergency number 144.
Even without symptoms, it makes sense to get in touch if you notice no effect or if it wears off much earlier than after previous treatments. Treatment area, dose and technique are among the things reviewed. A lack of effect alone does not prove that antibodies have formed.
We explain what we offer and the facial areas treated on our page on botulinum toxin treatment in Zurich. Which treatment suits your findings can only be assessed individually.
Frequently asked questions
Does the effect last equally long on the forehead and around the eyes?
Not necessarily. The treated muscles, the dose and the product all influence the course. Three to four months are a general guide, not a fixed duration for every facial area.
Can the effect last longer?
Yes. In some people a change remains visible for longer, and review articles occasionally describe courses of up to about six months. This does not allow a prediction of your personal duration, either for the first treatment or for later ones.
Does each further treatment automatically last longer?
No. With repeated treatments the effect may last longer, but this does not happen reliably in everyone. A fixed increase from the first to the second treatment cannot be promised.
How do I plan a treatment before a special occasion?
Discuss the occasion with the practice in good time. The effect is not visible immediately and develops individually, and bruising can also occur. A particular appearance on a particular date therefore cannot be assured.
What happens if I do not want any further treatment?
You do not have to continue the treatment. The muscle-relaxing effect fades, movement returns and expression lines may become more visible again. If you want to stop because of side effects or an unwanted result, please still discuss this with the practice.
This article does not replace a medical examination.
