Exaggeration of wrinkles after botulinum toxin injection for forehead horizontal lines.

There have been no long-term complications or life-threatening adverse effects related to botulinum toxin treatment for any cosmetic indications. Nevertheless, there are well-known, mild side effects of botulinum toxin treatment on the upper face, though most of them are self limited with time. However, excluding brow ptosis, reports about site specific side effects are few and anecdotal. We experienced cases of exaggeration of wrinkles after botulinum toxin injection for forehead horizontal lines, and report them here. In our cases, new appearance of a noticeable glabellar protrusion following botulinum toxin injection on the forehead was observed in 2 patients. Also, a new deep wrinkle on one side of the forehead just above the eyebrow appeared in another 2 patients. The exaggerated wrinkles nearly disappeared without treatment by week 4 in all subjects. These exaggerations of wrinkles may be caused by hyperactivity and overcompensation of untreated muscles. With the increasing availability of diverse botulinum toxin for cosmetic purposes, physicians and patients should be aware of this temporary change after therapeutic injections. We recommend explaining this possible effect prior to injection, for better understanding of treatment for cosmetic indications.