ABSTRACT
Beautiful appearance is important for many people particularly with aging. Botulinum A toxin has been used for cosmetic purposes for several years. One of its applications is removal of hyper dynamic facial lines. Its use is very popular due to cheaper and more simplicity, compared to the surgical methods. Also most patients are interested to using it for the second time. Therefore, the aim of this study was to evaluate in the onset and duration of action of this toxin, following the first and the second injection compared to the first injection. This interventional study, was carried out on 61 patients [48 females and 13 males] referred to Al-Zahra and Kashani hospitals of Isfahan for treatment of their facial hyper dynamic lines. At the first visit, 25 units of botulinum were injected at 5 points of the face of the patients and followed up for 6 months. At the end of 6 months, the second injection was administrated to the available patients [25 individuals] using the same dose of toxin and locations. The onset and duration of action in the two periods were recorded. The data was analyzed using t-test. The onsets of clinical actions following the first and the second injections were 3.1 +/- 0.77 and 1.5 +/- 0.41 days, respectively [p<0.001]. Means of the duration of action for the first and the second injection were 14 +/- 2 and 18 +/- 2 weeks, respectively [p>0.05]. The onset of action for the second injection was faster. However, there was no significant difference in duration of action between the two injections