A small trial by South American investigators evaluated 12 women and suggested that injecting the orbicularis oris muscle with onabotulinumtoxinA 1 week before treating upper-lip vertical rhytides with trichloroacetic acid and dermasanding improved results (Dermatol. Surg. 2007;33:1066-72).
Dr. Cohen has been a consultant or researcher for Allergan, Medicis, Johnson & Johnson/Mentor, and Merz.