To answer this question, I will first talk about the original studies on Botox® Cosmetic that got the product FDA approved. The first study was done with 20 UNITS of Botox® Cosmetic to the Glabellar lines ( frown lines in between the eyebrows). The study showed that at 3-4 months, 75% of all participants in the study got their movement back.
In my experience of doing Botox® Cosmetic on tens of thousands of patients, it is RARE for Botox® Cosmetic to last 4-6 months. Having said that, there are some generalities to patients that experience longer lasting Botox effects:
1. Patients that use the fully recommended dosage of 20 units of Botox® Cosmetic for the glabellar and 24 units of Botox® Cosmetic for the crow’s feet will experience longer lasting effects. If you use only 6 or 8 units of Botox® Cosmetic for the glabellar, the results will be a nice softening of the lines, a more natural look, but your lines will come back in 2 months. I have many patients that choose this “softening” alternative, knowing that they will come back every 2 months, but they have a more “natural” look instead of the “frozen” look.
2. Younger patients (20-33 years old) will experience longer lasting effects. So as you age, your Botox® typically will not last as long as when you first started doing it 5 years ago.
3. First time patients (virgin patients) seem to have longer lasting effects. This effect is probably more psychological than physical, similar to someone getting drunk for the first time or smoking their first cigarette. You’ve had these lines for years and then you do Botox® and suddenly in one week, your lines have disappeared completely. It is the dramatic transformation of your first time, and it appears to you that the Botox® takes 10 years off your face. You only experience your first Botox® results ONCE, and this dramatic transformation gets imprinted in your mind so strongly that subsequent experiences with Botox® may not be quite as satisfying.
4. Patients that have a fuller face or more fat in their face will typically have longer lasting Botox® effects. Fat on the body doesn’t look so great, but fat in the face makes us look younger. Typically heavier patients have longer lasting Botox® effects. If you are a body builder, marathon runner, yoga instructor, or just thin framed, your Botox® will typically wear off quicker.