A review of the longevity of effect of botulinum toxin in wrinkle treatments.

Botulinum toxin is widely used in facial rhytide treatments. The duration of its effects influences treatment intervals, cost and convenience to the patient. These are key factors in successful aesthetic procedures. A review of the literature found that duration of effect was between two and six months, with most experiencing loss of maximal contraction for three to four months. Treatments may last between three to four months, and occasionally up to six months. No specific definition of effectiveness/efficacy has been described and used to measure comparable end points. Additional research should help clarify the impact of brand, age, gender, ethnicity, repetition of treatment and zinc-phytase supplementation.