01Why corners turn down
The corner of the mouth is pulled downward by the depressor anguli oris, a muscle running from the lower jaw up to the corner. It normally works against the muscles that lift the corner.
With age and repeated use that balance shifts, so the corner sits lower even at rest.
The support underneath is the part most often missed. Deep fat around the corner and along the jawline reduces with age, alongside changes in the underlying bone.
When the base recedes, the tissue above it settles downward.
Patients rarely describe this as a change in lip shape. They describe being told they look tired or unhappy when they feel neither.
- Downward muscular pull outweighing the lifting muscles
- Reduced deep fat around the corner and jawline
- Less resilient skin and support layers, letting tissue settle
02Why lip filler does not help here
Lip augmentation works on the lip body — the visible pink portion — making it fuller or more defined. The corner sits at the end of the mouth line, and its position is set by muscular pull and the support below it, not by volume inside the lip.
Adding volume while the cause remains produces a fuller lip on a frame that is still descending, which sometimes makes heaviness at the corner more noticeable rather than less.
This is why assessment matters more than the choice of procedure. If the goal is a corner that no longer reads as downturned, treating the lip body addresses a different structure entirely.
03Perioral lines are a separate problem
The fine vertical lines above the upper lip are a different mechanism. They come from the circular muscle around the mouth contracting repeatedly during speech, drinking through a straw or pursing, combined with skin that is thinner and has fewer oil glands than elsewhere on the face.
Sun exposure accelerates this by degrading collagen and elastin, which is why unprotected sun exposure often brings these lines earlier than age alone would predict.
Because the causes differ, the approaches differ, and something that helps one may do little for the other. Treating everything around the mouth as a single problem is what leads to the wrong choice.
Main cause
When visible
Location
Does lip volume help?
This table explains mechanisms; it is not a self-diagnosis tool. Real assessment requires viewing the face at rest and in movement.
04How it is assessed
A proper assessment looks at the face both at rest and in movement, because something visible only during movement points to a different cause than something present constantly. The physician separates what comes from muscular pull, what from lost structure, and what from skin quality.
In practice most people have more than one mechanism at once, so a sensible plan is usually a sequence — deciding what to address first — rather than a single procedure.
Useful questions to ask before deciding:
- How much of this is muscle, how much lost structure, and how much skin?
- If the result is not what we discussed, can it be adjusted, or do we wait — and how long?
- Are there cautions given my medical history and current medication?
- What should I avoid afterwards, and when should I return for review?
- If I do nothing, how would this change over time?
05Cautions and limits
The area around the mouth controls speech, eating and expression. Treatment at an unsuitable site or amount can affect function, not only appearance — for example temporary difficulty controlling the mouth, or an asymmetric smile.
Results differ between individuals according to anatomy, age, skin quality and habits. No approach performs identically for everyone, and none halts the ageing process.
Tell your physician beforehand about any neuromuscular condition, pregnancy or breastfeeding, and any medication affecting blood clotting.
This article is for general understanding. It is not a diagnosis or individual treatment advice and does not replace consulting a physician.
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06Common questions
Will lip filler lift my mouth corners?+
Can downturned corners and perioral lines be treated together?+
At what age do mouth corners start to turn down?+
If I do nothing, will it keep getting worse?+
Will treatment make speaking or eating difficult?+
08References & further reading
- Yi K-H et al. Novel anatomical proposal for botulinum neurotoxin injection targeting depressor anguli oris for treating drooping mouth corner. Anat Cell Biol. 2023;56(2):161–165.Hyperactivity of the depressor anguli oris can lead to a sad, tired, or angry appearance; its borders overlap adjacent muscles, and imprecise technique risks an asymmetrical smile.
- Moradi A, Shirazi A. A Retrospective and Anatomical Study Describing the Injection of Botulinum Neurotoxins in the Depressor Anguli Oris. Plast Reconstr Surg. 2022;149(4):850–857.The depressor anguli oris lowers the lateral corners of the mouth; treating it allows the lip elevators to reposition the corners. Proximity to the depressor labii inferioris can cause lip asymmetry.
- Morera Serna E et al. Anatomy and Aging of the Perioral Region. Facial Plast Surg. 2021;37(2):176–193.Sun exposure, bone resorption, dynamic muscular contraction, gravity and histological skin change together produce fine lip wrinkling, downturned mouth corners and marionette lines.
External sources · last verified 2026-08-18