This study was designed to investigate the effects of botulinum toxin type A injections diluted with the mixture of sodium bicarbonate (SB) and normal saline (NS) on pain reduction, onset of action and duration of action.

This is a prospective, randomized, double-blind clinical study, which included 30 female patients (age>25). The patients were randomized to receive botulinum toxin (BT) injections diluted with NS and SB on one side of the face and saline control injections on the other side. Pain severity was assessed using visual analogue scale. The onset and duration of action were recorded according to the patients' subjective opinions after 1 week and 3 months, respectively. The study was approved with an IRB (Institutional Review Board) number of RC19/371.

Inclusion Criteria:

• Any female patient who is in good health and has moderate dynamic forehead and glabellar wrinkles.

Exclusion Criteria:

• • Patients <25 years old

  • Presence of neuromuscular disease or intake of drugs affecting muscle tone.
  • Any active infection in the treatment area.
  • Patients receiving anticoagulation or had a diagnosis of bleeding disorders.
  • Any patient who had undergone the following treatments to the forehead area in the past 6 months: botulinum toxin injections, ablative laser procedures, radiofrequency device treatments, ultrasound device treatments, or medium to deep chemical peels.
  • Any patient who had temporary soft-tissue augmentation material to the forehead area in the past 12 months, semi permanent soft-tissue augmentation material in the past 2 years, or permanent soft-tissue augmentation material at any point in the past.
  • Any patient with prior facial cosmetic surgical procedures such as eyebrow-lifts, blepharoplasties, and rhytidectomies.