Depressor Anguli Oris (DAO) Treatment: How Relaxing This Muscle Lifts the Lower Face

The depressor anguli oris (DAO) is often overlooked in favour of more popular treatment areas, but understanding its role in facial expression can produce profound changes in a patient’s overall appearance. In certain cases, relaxing this muscle creates the visual impression of a lifted face.

Understanding the Role of the Depressor Anguli Oris

The DAO is a paired muscle located on either side of the chin. It originates from the mandible and extends upward and outward to insert into the modiolus at the corners of the mouth. Functionally, the DAO pulls the corners of the mouth downward during facial expressions such as frowning or expressing sadness or displeasure.

In many individuals, particularly with age, this muscle becomes overactive. This overactivity contributes to a resting facial expression that appears stern, tired, or discontent, even when the individual feels neutral or relaxed. Over time, the downward pull from the DAO can cause the oral commissures to droop, accentuating marionette lines and deepening shadows around the mouth. These visual cues are often interpreted by others as signs of fatigue, frustration, or sadness.

Many patients presenting in clinic are not aware that this is the source of their concern. They may simply describe looking “grumpy,” “miserable,” or like they are frowning when their face is at rest. Often, they report that others misread their mood based on these static expressions. This mismatch between internal state and external appearance can significantly affect confidence and interpersonal interactions.

How Relaxing the DAO Can ‘Lift’ the Face

When we use botulinum toxin to reduce the activity of the DAO, we interfere with its ability to pull the mouth corners downward. This intervention allows the natural lift of the zygomaticus major and minor muscles, which elevate the mouth corners during smiling, to become more dominant.

The resulting effect is a subtle lifting of the corners of the mouth. While no volume is added, and no tissue is physically lifted, the balance of muscular forces changes. By reducing the downward vector, we reveal the natural upward tension that has been masked by DAO overactivity. In this context, relaxation becomes elevation.

Patients who receive this treatment often describe a gentler, more approachable expression. They may note that they look “less tired” or “less cross,” even if they have not consciously identified the downward pull before. This treatment is particularly satisfying because it addresses the cause of the problem, muscle activity, rather than simply masking its effects with filler or surgical intervention.

Anatomical Considerations

Anatomical precision is essential when treating the DAO with botulinum toxin. The DAO lies superficially over the lateral chin, extending upward toward the mouth corners. It is often shaped like a vertical triangle and sits between two important neighbouring muscles, the depressor labii inferioris medially and the platysma laterally.

If toxin spreads too medially or too deeply, the depressor labii inferioris may be affected (which is responsible for lower lip movement). Patients may then experience difficulty with lip control, smile asymmetry, or a “crooked” appearance when speaking or smiling.

To identify the DAO, practitioners should ask the patient to perform an exaggerated frown or pull the mouth corners down. This action highlights the muscle’s position and allows for accurate palpation. Typically, a single injection point is used on each side, located lateral to the marionette line, approximately one to two centimetres above the inferior border of the mandible.

In Summary

The DAO exemplifies how a deep understanding of facial anatomy allows us to produce meaningful aesthetic changes with minimal intervention. By selectively reducing the influence of a single downward-pulling muscle, we can shift the emotional tone of the entire lower face. In many cases, the result is not a dramatic transformation, but a gentle return to a more neutral, contented, and approachable expression.