Assessing the Efficacy and Safety of Intradermal Injection of Different Doses of Botulinum Toxin Type A: A Randomized, Double‐Blind, Placebo‐Controlled, Split‐Face Pilot Study in Rosacea Patients with Erythematic Telangiectasia

Introduction. Rosacea is a common chronic inflammatory skin disease of the central facial skin with unknown origin, significantly impacting quality of patient’s life and causing various psychosocial problems. Erythematotelangiectatic rosacea (ETR) is characterized by paroxysmal flushing that occurs repeatedly and is easily resistant to therapeutic drugs. While microinjection of type A botulinum toxin (BTX) can treat ETR, there is no consensus on the injection dose, and strong evidence to verify its efficacy and safety is lacking. This randomized, double‐blind, split‐face clinical study aimed to investigate the efficacy, safety, and optimal dose of two different single‐point injection doses (0.5 U and 1 U) of BTX in the treatment of rosacea. Methods. Twenty‐six patients with ETR were randomly assigned to receive different single‐point injections of BTX (0.5 U and 1 U, respectively) every 1 cm on one half of the face. The Clinical Erythema Score (CEA), VISIA red area absolute value, Global Aesthetic Improvement Scale Score (GAIS), and recurrence at 12‐week follow‐up were evaluated at baseline, 2,4, 8, and 12 weeks after injection. Additionally, the Dermatological Quality of Life Index (DLQI) questionnaire survey and adverse reactions were also recorded. Results. All twenty‐six patients completed the follow‐up visits and were included in the analysis. Compared to the 0.5 UBTX‐treated side, the CEA score showed significantly improvement in erythema and flushing at 2, 4, and 8 weeks after injection on the 1 U BTX‐treated side (P < 0.05). The mean absolute value of the red area of VISIA was ‐19.12 ± 51.91 on 1 U BTX‐treated side and 2.5 ± 42.08, on 0.5 UBTX‐treated side at 4 weeks after treatment, showing significant improvement on the 1 U side (P < 0.05). GAIS and DLQI were also significantly improved from Week 4 to Week 12 and Week 2 to Week 12, respectively (P < 0.05). There was no recurrence of symptoms with either 0.5 U or 1 U injection by 12 weeks. Apart from one patient who experienced facial tightness and three patients who had temporary aggravation of erythema, all of which resolved without treatment, 22 patients did not report any side effects except for injection pain during the procedure. Conclusions. BTX‐A can significantly improves symptoms and quality of life in patients with refractory rosacea with few side effects. A single‐point injection of 1 U was more effective. This trial is registered with NCT06282679 .