Droopy corners of mouth can be caused by a combination of factors. One of the main ones is hypertrophy of the Depressor Anguli Oris (DAO) muscle, which also contributes to marionette lines and gives the impression of being unhappy. By relaxing the DAO, the zygomaticus muscles will be able to work unopposed to elevate mouth corners. Botulinum toxin treatment in this area may also be combined with dermal fillers for address volume loss.
One injection (of 2 units of botulinum toxin) should be injected into the posterior aspect of each DAO. The injection point should be at least 1cm lateral to the corner of the mouth. Never inject medial to the marionette line.
Additional injection points to target platysma muscle may be required depending on clinical findings
It is always advisable to start with a low dose and titrate up at each follow up session.