Botulinum Toxin for Crow's Feet: Indication and Care

The lateral lines of the eye, popularly called crow's feet, are among the most frequent concerns in facial harmonization practices. They seem simple to treat, but they hide delicate decisions: the patient wants to soften the lines without losing the smile, and the muscle involved, the orbicularis oculi, takes part both in expressing joy and in protecting the eye.

This page lays out a line of reasoning for indication and follow-up. It gives no injection points or doses, which depend on training and individual assessment, at the discretion of the qualified professional and in line with the rules of their professional council.

What causes the lateral lines of the eye?

The origin is multifactorial. Repeated contraction of the lateral portion of the orbicularis wrinkles the skin and forms radial folds from the outer corner. Over time, these folds no longer disappear at rest and become static lines, in which collagen loss, sun exposure, smoking and genetics all play a part.

Smile pattern, skin thickness and the underlying fat also matter. People with an "eye smile" (one in which the eye partly closes) tend to have more marked lines, while those who smile more with the mouth may have subtler lines. Thin, dry skin accentuates the look.

To understand the basics, it is worth reviewing dynamic wrinkles and static wrinkles. In many patients both coexist, and the plan needs to make clear which part responds to toxin.

How does the lateral orbicularis behave?

The orbicularis is a ring-shaped muscle. Its lateral orbital portion contributes the most to the radial folds and to the drop of the brow tail during forced contraction. It works in opposition to the frontalis, which lifts the brow, and to the brow elevator. The balance among these muscles determines the position of the brow tail at rest and in expression.

That is why treating the lateral orbicularis requires thinking about the brow. Reducing orbicularis action can subtly lift the tail, which is sometimes wanted and sometimes creates a shape the patient does not want. In someone whose frontalis is already very active, the response differs from that of someone with a drooping brow.

Who benefits, and who does not?

In general terms, toxin tends to make more sense when the line is predominantly dynamic, the skin has reasonable thickness and the patient accepts a result of softening, not erasing. Patients with deep static lines, very thin skin or excess skin may benefit more from other strategies, such as skin quality treatment, collagen induction or combinations.

See also toxin in thin, sun-damaged skin, which discusses the limited response in skin with significant sun damage.

What are the most relevant risks?

The main adverse events, when the area is treated, include:

• Local ecchymosis and swelling, mainly because of the rich superficial vascularization of the area.
• Asymmetry of the smile and the lines, due to differences in activity or response between the sides.
• Spread to the zygomaticus major or the levator labii superioris, causing a drooping smile or upper lip.
• Diplopia or altered eye movement, rare and linked to spread to the extraocular muscles.
• Dry eye or tearing, due to reduced efficiency of the tear pump.
• Brow ptosis or a heavy look when there is an imbalance with the frontalis (see heavy look after toxin).

Safety depends on knowing the anatomy and respecting the limits of the area. When in doubt, the principle is to treat less and reassess. Broader complications are covered in complications with botulinum toxin.

What to ask and record beforehand?

Besides the general history, a few questions help anticipate problems:

• Does the patient wear contact lenses or complain of dry eye?
• Have they had eyelid surgery, laser, peels or other procedures in the area?
• What is their profession? Do they work in front of cameras, teach or speak in public?
• Do they play water sports or contact sports with a risk of eye injury?
• Have they had toxin before? How was the response and the duration?
• Is there a neuromuscular disease or use of medications that interfere with neuromuscular transmission?

How does toxin combine with other strategies?

Few patients resolve the concern with toxin alone. When there is a static component, a common approach is to add skin quality treatments or biostimulation, always at the professional's discretion. See hyaluronic acid in the lateral periorbital lines, which discusses the area with dermal filler, the specific risks and the need to have hyaluronidase available, and skin booster for under-eye circles, for the skin quality context.

The key point is not to promise that one treatment will fix everything. Static lines tend to improve only partly, and the patient needs to know that before deciding.

How to follow up afterward?

The follow-up visit is useful for assessing symmetry and discussing maintenance. The effect usually sets in within a few days and peaks around two weeks, with individual variation. If there is a difference between the sides that bothers the patient, it is reasonable to observe before correcting, because the response may even out.

How to handle the patient who asks for "more"?

It is common for a dissatisfied patient to want a top-up in the very first week. Resist: the effect is still developing. Topping up without reassessing raises the risk of asymmetry and loss of expression. It helps to have a clear touch-up policy, stated in the consent, saying when and under what conditions a complement will be considered.

How to document?

Record the concern, line type, baseline asymmetries, risks explained, alternatives and follow-up plan. Always compare photos under identical conditions, following standardized clinical photography and dynamic photos for toxin. Image storage follows the rules in consent and LGPD for photos (in Brazil, the General Data Protection Law).