Onabotulinumtoxin Type-A Dosage for Upper Face Expression Lines in Males: A Systematic Review of Current Recommendations.

BACKGROUND Botulinum toxin is the most commonly performed minimally invasive aesthetic procedure in men. Despite various recommendations by experts on the use of botulinum toxin type A in the literature, distinct guidelines for its use in males and females do not exist. OBJECTIVES To delineate safe and effective doses for the use of Onabotulinumtoxin type A in males for correction of upper facial expression lines. METHODS PubMed (MEDLINE), EMBASE, Cochrane database, and Google Scholar were searched from 2002 to 2019 inclusive. Three researchers independently assessed trials for inclusion, extracted data, checked them for accuracy and assessed the evidence using AGREEII. RESULTS Average dosing for the treatment of upper face expression lines was noted specific to glabellar frown lines, crow's feet and horizontal forehead lines since 2002. Changing trends and gender variation in each of the studies was noted. 6 of the 11 recommendations suggest the need to alter dosing in male patients, although do not give separate recommendations. CONCLUSIONS The results suggest the urgent need for up to date recommendations for the use of Onabotulinumtoxin type A in upper face expression lines of male patients.