Sure wish there was an easy answer for that one! Neurotoxin for wrinkle relaxation is sold by the unit, or the area; depending on the clinic you choose. The amount of product it will take for wrinkle reduction is truly individualized. Lot's of things play into this including anatomy, age, treatment area and amount of correction desired. One overly simplified answer you may find on the internet is ‘one-unit-per-year-of-age for full correction’. Of course that may or may not be true for you, and serves only as a loose reference!
You may recall an earlier blog post where I mentioned that toxin works very well for “wrinkles of animation” (those that you see when you scrunch your face). Some rest-wrinkles may soften with toxin, but not disappear completely. Dosing can be aggressive or conservative. If you’re a first timer, you might want to “go light”—with the option for additional product at your follow up visit. If this approach is used just keep in mind that you may not achieve full correction (complete relaxation) and that the effect should not be expected to last the anticipated 3-4 months. But there isn’t a clear long term issue with this approach! Some deeper animation wrinkle lines benefit from relaxation “training”, and if you are committed to full correction every three to four months treatment you may note more dramatic relaxation and longer treatment effect after a year or so!
After a treatment I encourage you self-analyze its effect at two weeks or a month post treatment--that helps guide dosing for the next session. And as you evaluate focus on whether or not you continue to have movement, not whether or not a wrinkle remains. Repeated contraction can cause a little etching in the deeper layers of skin. Those may reduce over time with repeated relaxation, or you might be a candidate for other treatments to complement the neurotoxin, like lasers, microneedling or threads.
On label (meaning the FDA approved the product based on scientific data for efficacy and safety) dosing for onabotulinumtoxin A (aka Allergan's Botox®) is 20 units for the glabella (area between your brows); frontalis (forehead) is up to 20 units, and lateral canthal lines around the eyes (crows feet) is 12 units per side. There are other areas which are commonly treated "off label" (the industry generally feels it is safe, however there is no FDA formal approval simply because the cost of doing a study may be cost prohibitive).
Bottom line: there are generalities for dosing, but you are unique, and your goals and aspirations guide my recommendations. Come in! Let's chat about it!