Crow's Feet: Botulinum Toxin, Fillers, and How to Choose Between Them

The fan-shaped lines radiating from the outer corner of the eye — commonly known as crow's feet — are among the most frequently raised concerns in facial aesthetics. They form through repeated contraction of the periorbital muscles during everyday expression: squinting, smiling, laughing. This overview covers the two main treatment approaches at a conceptual level and is not an injection protocol.

Why Crow's Feet Form

Crow's feet develop faster in skin that is thin, dry, or has had significant cumulative sun exposure, and they are also associated with reduced natural collagen and hyaluronic acid in the skin over time. Because they are driven by repeated muscle movement, they are classed as dynamic lines — most visible during expression — though with time they can become more persistent at rest as well, as repeated folding gradually etches the pattern into the dermis independent of active muscle contraction.

For patients whose only concern is the lateral canthal area — with the upper and lower eyelids otherwise unaffected — a non-surgical approach is generally appropriate, and surgical intervention is rarely the first-line consideration.

Botulinum Toxin: How It Works

Botulinum toxin is typically the first-line approach for dynamic periorbital lines because it addresses the underlying cause — repetitive muscle contraction — rather than the surface line itself. It acts by temporarily blocking nerve signalling at the neuromuscular junction, which relaxes the targeted muscle and reduces the movement that creates the crease. Results are not immediate and build over the days following treatment.

Effects are commonly described as lasting in the region of three to five months, after which muscle activity — and the associated lines — gradually return to baseline, which is why maintenance treatment is part of any realistic plan. Tolerance to repeated toxin treatment can occur in a minority of patients over time, and newer formulations entering the market are increasingly positioned around reducing this risk, though this remains an evolving area.

Dermal Filler as an Alternative or Complement

Because periorbital skin is thin and sensitive, filler used in this area generally calls for a well-purified, resorbable hyaluronic acid product. Rather than relaxing the muscle, filler works by adding volume and hydration beneath the skin, which softens the visible crease and supports overall skin quality in the treated area. Results from HA filler in appropriate areas can last considerably longer than toxin — commonly cited in the range of several months up to around a year, depending on the product and area — and are reversible with hyaluronidase if needed.

Filler is not automatically appropriate for every periorbital presentation: where a patient also has under-eye puffiness or fluid retention in the area, HA's water-binding property can aggravate that concern, and a more cautious, individualised assessment is warranted.

Choosing Between the Two

• For lines that are primarily driven by muscle movement, botulinum toxin is generally the more direct approach.
• For lines that persist at rest, or where associated volume or hydration loss is a factor, filler may be considered, either alone or alongside toxin.
• Combination approaches — toxin to address the dynamic component and filler to support skin quality — are common in practice.

Correcting Patient Misconceptions

Some patients arrive with outdated expectations shaped by more heavily treated results seen years ago, either wanting a fully "frozen" look or, more often, worried treatment will leave them looking unable to express emotion. Modern toxin formulations and technique are generally used more conservatively than in the past, and a frozen appearance is now the exception rather than the expected outcome — a point worth addressing directly in consultation, since it shapes how comfortable a hesitant patient feels about proceeding.

Safety and Candidate Assessment

Whichever approach is used, treatment should only be undertaken by a suitably trained and licensed practitioner following a proper assessment of the patient's anatomy, expression patterns, skin quality, and medical history. Both approaches carry a low but real risk of bruising, swelling, or asymmetry, and patients should be counselled on what to expect and when to seek follow-up. Standard contraindications apply, including pregnancy and lactation, active infection at the treatment site, and certain neuromuscular conditions — a thorough medical history should precede any treatment decision.

The Takeaway

Crow's feet respond well to both botulinum toxin and dermal filler, but the two work through different mechanisms and suit somewhat different presentations. A careful assessment of whether the lines are primarily dynamic, static, or accompanied by volume loss should guide the recommendation — and combination approaches are often the most effective route.

To review HA filler options suitable for delicate periorbital use, browse the dermal fillers range.