When does the effect of botulinum toxin treatment begin and how long does it last?

When does the effect begin?

Studies have shown that the first changes in the glabella region are reported in some patients within the first 24–48 hours, while in many others it takes approximately 2–5 days. However, the effect does not necessarily begin on the same day in every patient.

When can the full effect be assessed?

It is generally more meaningful to wait about 10–14 days to evaluate the clinical outcome. During this time, muscle activity may decrease and initial minor asymmetries may change.

If there is movement after 14 days, does that mean the treatment has failed?

No. The goal isn't always to completely immobilize the muscle. In techniques aimed at preserving natural facial expressions, a certain amount of movement can be deliberately left out.

How long does the effect last?

In classic aesthetic botulinum toxin A applications, the effect lasts approximately 3–4 months in most patients. In OnabotulinumtoxinA glabella studies, the median duration of effect was found to be approximately 120–131 days. In some areas and preparations, a clinical response of 4–5 months or longer may be observed.

Why does it vary from person to person?

Muscle size and strength, dose, area treated, anatomical features, preparation used, injection technique, and how the clinical "end of effect" is defined can all affect the duration.

Does a higher dose last longer?

Some controlled studies have shown that increasing the dose prolongs the duration of effect. However, higher doses are not always better; the risk of unwanted muscle weakness and facial changes may increase.

Does the effect end suddenly?

Usually not. Muscle movement gradually returns.

Can it be repeated before three months?

Routine reapplication at very short intervals is not preferred. High total dose, frequent injections, and short intervals are considered potential risk factors for neutralizing antibodies. Clinically significant antibody development is rare at aesthetic doses.

If botulinum toxin is no longer as effective as it used to be, could it be due to the development of antibodies?

Not always. Factors such as dosage, injection points, product preparation/storage, use of different preparations, or changes in expectations should be considered first.

Do brands have different initial impact phases?

Some comparative studies have reported differences; however, the units of the products are not exactly equivalent, and the onset time alone does not predict persistence.

Are Azzalure and Dysport the same toxin?

Both contain abobotulinumtoxinA. Commercial presentation and approved usage details may vary by country. Just because a patient notices a faster effect in one application does not necessarily mean the product will be faster or longer-lasting in everyone.

Judging the outcome of botulinum toxin treatment too early can lead to unnecessary additional doses. A more accurate clinical approach is to separate the onset of effect from the full effect, and to consider how much of the natural effect needs to be preserved during an evaluation lasting approximately two weeks.

Dermatologist's Perspective