Misplaced Botox in DAO muscle. Will it always result in dropping?

Thank you for your question pompbeauty. I understand
your concern. Botox is a purified protein used to address wrinkles associated
with facial expression. It is most commonly used to treat wrinkles in the upper face such as the horizontal lines seen on the upper forehead when one raises the brows, the vertical lines seen between the brows when one frowns, and the crow's feet seen around the eyes when one smiles.Over the past decade the use of Botox cosmetic has spread to other areas on the face and neck. Botox can be used in the bunny lines on the nose (nasalis muscle), around the lips to provide a pout (orbicularis oris muscle), just beneath the nose to address a downturned nose when one smiles (vestigial depressor septi nasiii muscle), above the lips beside the nose to address a gummy smile (LLSAN muscle), in the lower face to contour the face or address pain associated with TMJ (masseter muscle), on the chin to address dimpling or a cobblestone appearance (mentalis muscle), and on the neck to address neck bands and lift the jawline (Nefertiti lift, platysma muscle). Botox can also be placed in a muscle in the lower face called the depressor anguli oris (DAO). As its name implies this muscle pulls down on the corner of the mouth. When Botox relaxes this muscle the corner of the mouth is elevated by approximately 1-2 millimeters and can improve a sad face appearance. It is also often used in conjunction with fillers for the marionette lines in this area.With any injection there is a risk for pain, bleeding, bruising, redness, swelling, tenderness, and infection. With Botox treatments there is also a risk of spread of the product to nearby muscles. For example, when treating the area around the eyes, Botox rarely spreads to the levator palpebrae superioris muscle, which is responsible for raising the upper eyelid. This leads to a droopy eyelid and is treated with apraclonidine ophthalmic solution. If injections to treat the crow's feet are placed too low, the product can spread to the nearby zygomaticus muscles, leading to a temporary asymmetric smile. In the case of the DAO muscle, Botox may spread to the adjacent depressor labii inferioris (DLI). This muscle is responsible for pulling down on the lower lip and if it is relaxed one can also have a temporary asymmetric smile. This can also occur with treatment of the mentalis muscle on the chin as the DLI muscle sits between the mentalis and the DAO.In order to prevent side effects it is important to use a low dose (2-4 units per side) and place the product in the correct location. I ask patients to show me their lower teeth or say the letter "E." This allows me to visualize the bulge of the DAO muscle. I place the Botox in the bulge of the muscle toward the jawline. This decreases the risk of diffusion of the Botox to the DLI muscle.Of note, the marginal mandibular nerve is the nerve that innervates the DLI muscle. This nerve can be affected if Kybella injections are placed too high when treating the double chin. In the pivotal studies all of the subjects with such adverse effect had complete resolution. Median duration of the asymmetric smile was approximately 6 weeks.
Please follow up with your doctor for specific
recommendations. Good luck!

Careful and professional Botox injections rarely result in any untoward results. Remember that this is a medication that relaxes muscles for a number of months. If it is injected into an unintended muscle you may have to live with a less than optimal result for a while (it always returns to normal though!).  The muscle under the lower lip is called the DAO and it functions to pull the lip down when you smile. If it is weakened the result is an asymmetric smile (not a droop).  Injecting Botox in this area is considered "off label"  meaning that the FDA has not specifically approved it. 

Typically, misplaced Botox injection when treating the DAO muscle results in an asymmetric smile since the Botox commonly is misplaced or diffuses into the adjacent DLI muscle. The asymmetric smile returns to normal after 3-4 month when the Botox wears off. 

Botox not placed accurately in the DAO could result in asymmetry of the lip usually seen with smilling or could result in no effect at all.  It depends on the dose and the location.  Any asymmetry should resolve in a couple of months and go back to normal.  Best.

Please only see a specialist for injection of Botox, especially in non-traditional areas such as the DAO, an area injected to raise somewhat the corners of the mouth.  Dermatologists, plastic surgeons and head and neck surgeons are all familiar with the anatomy so it is unlikely they will 'misplace' such an injection.  It is possible to inject the wrong peri oral muscle and develop dropping of the angle of the mouth (one or both sides) but this is reversible.  It may take from weeks to months to correct depending on the amount of toxin used and where it was 'misplaced'.