DAO Injection Techniques: Everything Injectors Need to Know

| By Sparkle Lifestyle & MediSpa | Moncton’s Clinical Experts in Facial Harmonization

The Depressor Anguli Oris (DAO) muscle plays a big role in facial expression—and when it’s overactive, it can drag the corners of the mouth downward, creating a sad, angry, or tired appearance.

If you’re an injector aiming for full-face harmonization, understanding how to treat the DAO safely and effectively is essential. In this guide, we’ll break down anatomy, dosage, landmarking, advanced techniques, combination treatments, and common pitfalls.

Let’s lift those corners—with precision.

DAO-Advanced-Injection-Techniques

What is the DAO?

The Depressor Anguli Oris is a paired muscle on either side of the mouth. It originates from the mandible and inserts into the modiolus (the corner of the mouth). Its main function? Pulling the mouth downward during frowning or sad expressions.

When overactive, the DAO contributes to:

  • A tired, angry, or aged expression—even in neutral face.
  • Downturned mouth corners (resting frown)
  • Marionette lines (especially when combined with volume loss)

Why Inject the DAO?

Botulinum toxin (like Botox®, Dysport®, Xeomin®, or Nuceiva®) weakens this muscle, allowing opposing elevators (like the zygomaticus major and levator anguli oris) to pull the mouth corners up.

Benefits of DAO Treatment

  • Subtle lift of the mouth corners
  • Softer, more approachable resting expression
  • Reduced animation lines around the mouth
  • A more youthful and emotionally positive appearance
DAO-Advanced-Injection-Techniques

DAO Injection Technique

Landmarks:

  • Ask patient to frown; palpate the lateral band pulling the corner downward.
  • Muscle Activation: Ask the client to make a sad face or frown to better identify the DAO muscle.
  • Muscle Localization: Gently pinch the targeted area to confirm the muscle’s exact location.
  • Relaxation: Ensure the client’s facial muscles are completely relaxed before proceeding.
  • Injection point is typically:
    • 1.5–2 cm lateral to the mouth corner
    • At or just above the jawline

Technique

  • Needle: 30–32G, 4 mm insulin syringe
  • Depth: Superficial intramuscular (just below the dermis)
  • Angle: Perpendicular or 45° if very superficial
  • Dose per side:
    • Beginners: 2 units
    • Intermediate: 2–3 units
    • Experts: Up to 4 units (with care)

💡 Pro tip: Always start conservative. You can top-up at the 2-week follow-up, but you can’t reverse it.

Avoiding Common DAO Injection Mistakes

DAO seems simple, but it’s one of the most commonly mis-injected muscles. Here’s what NOT to do

Combining Neurotoxins with Dermal Fillers

The combination of treating the Depressor Anguli Oris (DAO) muscle with dermal fillers can be beneficial in certain cases. It is typically considered when there is a noticeable volume loss or asymmetry in the lower face, particularly around the corners of the mouth.

When the DAO muscle is overactive, it can contribute to a downturned or sad appearance. Botox or other muscle relaxants can be used to temporarily weaken the muscle and lift the corners of the mouth. However, in some instances, the volume loss in the area may also need to be addressed to achieve a balanced and harmonious result.

Dermal fillers can be used to add volume and restore symmetry to the lower face. By strategically placing the fillers in the surrounding areas, such as the marionette lines or the corners of the mouth, the downward pull of the DAO muscle can be counteracted. This combination approach can help to achieve a more youthful and lifted appearance.

It’s important to note that the decision to combine DAO treatment with dermal fillers should be made on an individual basis.

Disclaimer:

The combination of treating the Depressor Anguli Oris (DAO) muscle with dermal fillers can be beneficial in certain cases. It is typically considered when there is a noticeable volume loss or asymmetry in the lower face, particularly around the corners of the mouth.

When the DAO muscle is overactive, it can contribute to a downturned or sad appearance. Botox or other muscle relaxants can be used to temporarily weaken the muscle and lift the corners of the mouth. However, in some instances, the volume loss in the area may also need to be addressed to achieve a balanced and harmonious result.

Dermal fillers can be used to add volume and restore symmetry to the lower face. By strategically placing the fillers in the surrounding areas, such as the marionette lines or the corners of the mouth, the downward pull of the DAO muscle can be counteracted. This combination approach can help to achieve a more youthful and lifted appearance.

It’s important to note that the decision to combine DAO treatment with dermal fillers should be made on an individual basis.

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