Rare and novel complications of botulinum neurotoxin type A and dermal filler injections.

Botulinum neurotoxin type A (BoNTA) and filler injection procedures usually provide predicted outcomes with a low incidence of complications. Most of the complications after these procedures have been extensively discussed. In this study, we report on these injectables' less well-known, recently reported, and novel complications and attempt to clarify the underlying mechanisms. Counterfeit or mishandled BoNTA has been associated with botulism. BoNTA has been linked to uncommon complications, including morphea-like lesions, nontuberculous mycobacterial infections, vascular occlusion, and pseudoaneurysm of the superficial temporal artery. Unusual complications from filler injection include nonscarring alopecia, intraoral necrosis, nontuberculous mycobacterial infections, xanthelasma-like reactions, intracranial perforation, and pneumosinus dilatans. Post-BoNTA injection nodules and filler infection from bone destruction due to cocaine use are new complications. These complications pose a challenge for diagnosis and treatment. This publication aims to assist in promptly identifying and managing these rare and novel complications when necessary.