DAO lines at 25: treatment options and evidence
⚠️ Contact your injector promptly if you notice these after treatment
After any botulinum toxin injection near the mouth, contact your treating provider right away if you experience an asymmetric smile, difficulty closing your lips, trouble drinking or speaking clearly, drooping of the lower lip, or unexpected swelling or weakness that spreads or worsens. These can be signs that a neighboring muscle was unintentionally affected.
Short answer
Downturned mouth corners and early DAO (marionette) lines are driven partly by the depressor anguli oris muscle. The best-studied treatment is botulinum toxin injected into the DAO, sometimes combined with hyaluronic acid filler for added structural support. There is no evidence that oral collagen supplements treat these lines. Botulinum toxin results typically last about 4 to 5 months and filler longer. At 25, choosing to wait is also reasonable, and any treatment is best planned with a qualified, anatomy-trained injector rather than from a fixed dose or recipe.
What DAO lines are and why anatomy matters
The depressor anguli oris (DAO) is a small, thin muscle that runs from the jawline up to the corner of the mouth and pulls the mouth corners downward. When it is active it can contribute to a downturned mouth and to lines running from the mouth corners toward the jaw, often called marionette lines or DAO lines. These can appear at any age, including the mid-twenties. Anatomy studies show the DAO varies considerably between individuals in size, shape, and exact position, and it sits close to neighboring muscles such as the depressor labii inferioris and risorius. [1][2][3] That variability is why careful, anatomy-based placement matters for any injection in this area, since treating the wrong spot can affect the smile.
Treatment options at a young age
Botulinum toxin (neuromodulator). The product family that includes Botox, Dysport, and Xeomin is the option most directly studied for the DAO. In a prospective study, injecting a small dose into the DAO raised the mouth corners by an average of about 5%, with significant improvement in clinician and patient severity scores, although patients did not always rate the change as personally meaningful. [4] Ultrasound-based work reported that injecting along the labiomandibular fold at a depth of roughly 4 to 5 mm was safe and effective, [5] and a systematic review of botulinum toxin in the lower face found favorable results with high satisfaction and no serious adverse events reported. [6] Anatomy studies have mapped specific surface landmarks to help target the DAO while sparing nearby muscles. [3] The exact product, dose, and injection point are individualized by the injector; the literature reports typical ranges but cannot prescribe them for any one person.
Hyaluronic acid filler and combination approaches. Some studies pair botulinum toxin with hyaluronic acid (HA) filler. In a prospective evaluator-blinded study, HA placed at the mouth corners plus botulinum toxin into the DAO and mentalis produced improvement that was maintained at three months. [8] Larger multimodal work such as the HARMONY study reported high satisfaction when fillers were layered from the midface downward with botulinum toxin added for dynamic lines. [9][10] Filler adds structural support that does not depend on the toxin's duration.
Collagen claims. A distinction is worth making here. There is no peer-reviewed evidence in this literature that oral collagen supplements treat DAO lines. Separately, injectable collagen-stimulating products such as poly-L-lactic acid work by prompting the body to build collagen over time and are described as a longer-lasting filler-type option, but they address volume and support rather than the muscle pull itself. [10]
No treatment. Choosing not to treat is a reasonable option at 25, and is discussed further below.
How long results last, and what happens if you wait
Duration is a common concern. A large Cochrane review of botulinum toxin for facial wrinkles found an average duration of effect of about 20 weeks (roughly 4 to 5 months), varying by individual and area treated. [7] In DAO-specific work, improvement was well maintained at three-month follow-up. [4][8] Hyaluronic acid filler generally lasts longer, on the order of 6 to 18 months depending on the product and area, and collagen-stimulating products may last longer still, which is one reason combination approaches are discussed. [8][10]
Choosing to wait is also reasonable. Mild DAO lines at 25 that appear only with movement (dynamic lines) are unlikely to become permanently etched into the skin quickly. Botulinum toxin reduces the muscle activity behind the lines but does not change the underlying aging process, so postponing treatment does not close the door on it later. There is currently no strong evidence that early preventive treatment at a young age produces better long-term outcomes than treating later when lines become more noticeable. [7]
What to discuss with a qualified injector
If you decide to explore treatment, useful questions include: which anatomical landmarks or imaging (such as ultrasound) will be used to locate the DAO; how the injector chooses between botulinum toxin alone and combining it with a small amount of filler; what product and conservative dose they would consider for mild lines; how long results are expected to last; and what the plan is if mild asymmetry occurs. [3][11] Because DAO treatment is an off-label and anatomically delicate area, seeing an experienced, anatomy-trained, board-certified injector is especially important. [12]