BTX-A works by blocking the neuromuscular junctions around the injection sites. This prevents targeted muscles from contracting and hence the targeted muscle relaxes. With prolonged relaxation of the targeted muscles, loss of muscle volume may then occur, which is the treatment target in some areas.
BTX-A wrinkle treatment may kick in from 12 hours to 1 week after injection, with an average time-to-effect of 2 to 3 days. For muscle slimming, this may take anywhere between 1 to 4 weeks, depending on the size of the muscle and the dosage used.
Each treatment is expected to last between 3 to 6 months in duration – typically as one is exposed to more BTX-A treatments, the effect duration of each treatment tends to shorten.
BTX-A can be used to treat:
- dynamic lines around the eyes, commonly known as crow’s feet
- dynamic lines between the eye brows, commonly known as frown lines
- dynamic lines over the forehead
- dynamic lines around the nose, commonly known as bunny lines
- reduction of jaw (masseter) muscle for facial slimming and/or bruxism
- reduction of platysmal muscles of the neck/improve neckline definition
- reduction of shoulder blade or calf muscles (off-label)
BTX-A can also be administered along the facial and neck contours in multiple small injections intradermally (into the skin), known as a Dermalift.
BTX-A can also be used to treat conditions of excessive sweating, in particular the axilla.
Medical contra-indications aside, not all wrinkles can be treated effectively with BTX-A. As BTX-A works primarily on relaxing the muscles, dynamic wrinkles are the main focus of treatment, and fixed/static wrinkles (i.e. present without making any expression) may not respond to BTX-A treatment.
Some individuals may also develop treatment resistance to BTX-A especially after repeated exposure. This may be partial (whereby a partial therapeutic response is observed with standard doses) or complete (whereby no response is observed even with supra-therapeutic doses). Treatment resistance may or may not be associated with neutralizing antibodies to BTX-A, and isn’t fully understood.
It is common for individuals to notice that their effective duration of BTX-A decreases with repeated exposures, some to as short as 1 to 2 months of duration. Unfortunately, not much can be done apart to increase the dosages administered, or to administer more frequent treatments.
Before commencing any BTX-A treatment, one ought to know the potential side effects.
BTX-A side effects are by and large due to its local effects:
Direct Effect – Targeted Muscle
This may manifest itself as the sensation of stiffness, most commonly noticed when receiving BTX-A injections for the first time.
Direct Effect – Adjacent Muscle
For BTX-A injections around the eye, spread of the BTX-A may result in brow depression and/or upper eyelid depression (ptosis). Rarely, spread of BTX-A into the eye muscles may result in a squint or affect the vision.
BTX-A injections to the jaw muscles may result in an asymmetric smile due to the involvement of the muscles involved in smiling on one side of the face.
Secondary Effect – Muscle Volume Loss
BTX-A to the jaw muscles for jaw/masseter reduction is intended to induce muscle volume loss. However, some individuals may appear gaunt/haggard as a result, and the cosmetic outcome may not be ideal.
Duration of Side Effects
BTX-A only has a maximum effect of 6 months in duration and any side effects are expected to disappear by then.
BTX-A when used in cosmetic dosages does not cause generalized paralysis or breathing difficulties. Hence, cosmetic BTX-A does not kill, unless one has an extremely rare case of anaphylactic reaction to BTX-A.
There was an unfortunate incident of a young lady who died after treatment locally, which was wrongly attributed to BTX-A in the initial press releases, but subsequently clarified to be unrelated.
Overseas, deaths from BTX-A have been documented due to the use of unlicensed BTX-A products manufactured illegally, which contained many times the normal dosages of BTX-A.
In short, cosmetic BTX-A is not expected to kill.