Safety and Complications in HOF: An Overview

Injectable procedures in orofacial harmonization (HOF) are minimally invasive, but they are not risk-free. Most complications are mild and temporary. A small share are serious and depend on quick recognition. Between the two extremes, what makes the difference is preparation: careful assessment, anatomical knowledge, complication supplies on hand and a protocol the team knows before it is needed.

This article is a review-level overview. It is not a treatment protocol and does not include doses: managing each complication is the decision of the qualified professional, guided by current guidelines and the rules of their professional council (in Brazil).

Which complications are most common?

Complications can be grouped by severity and by when they appear.

Beyond these, infection and late inflammatory reactions can appear weeks or months later and call for clinical assessment.

Swelling and bruising: what to expect?

Swelling and bruising are the most frequent complications. The lips and the periorbital region, with their loose, highly vascular tissue, tend to swell and bruise more easily.

Points to watch:

• Telling the patient beforehand what is expected, with photos from your own practice when authorized, helps prevent anxiety.
• Ask in the medical history about anticoagulants, antiplatelet drugs and supplements that increase bleeding, and about important events in the following days.
• Tell the expected from the alarming: swelling that keeps getting worse, disproportionate pain or a net-like color change is not a simple bruise.

Nodules and the Tyndall effect

Nodules can be product accumulation (usually noticeable right after) or inflammatory reactions, which appear later. Telling them apart is a clinical call and guides the next step.

The Tyndall effect is the bluish discoloration caused by hyaluronic acid placed too superficially. It is more common in thin skin, such as the tear trough. Choosing the product and the plane, at the professional's discretion, lowers the risk. When it happens, it is usually treatable, including with hyaluronidase.

Vascular occlusion: why is it the most feared complication?

Vascular occlusion happens when the product enters a vessel or compresses it from outside. The area supplied by that vessel is left without blood. If it is not reversed in time, it can progress to skin necrosis. When the affected circulation connects with the eye's blood supply, vision loss can occur, a rare and critical event.

Which areas carry the highest vascular risk?

Some regions concentrate relevant vessels at hard-to-predict depths or with connections to the ocular circulation, and are cited as high vascular risk:

• Glabella
• Nose
• Nasolabial fold
• Temples
• Tear trough, in the under-eye area

This does not mean the others are exempt: the lips, for example, have the labial arteries. Anatomical knowledge, choice of product and instrument (cannula or needle) and technique are the professional's decisions, aimed at reducing that risk.

What are the warning signs?

During and right after the injection, watch for:

• intense pain, disproportionate to the procedure;
• pale or blanched skin in the area or in a distant territory;
• a purplish net-like pattern (livedo);
• slow capillary refill when pressing the skin;
• local coldness;
• in the following days, darkening, blisters or crusts;
• any visual change, eye pain, severe headache or neurological change: emergency.

Pain can be masked by anesthetic in the product or by a prior nerve block. That is why watching skin color and capillary refill is as important as the patient's report.

Why is hyaluronidase indispensable?

Hyaluronidase is an enzyme that breaks down hyaluronic acid. It is the main tool for reversing a filler made with that product, whether for excess, asymmetry, Tyndall or, above all, suspected vascular occlusion.

In any hyaluronic acid injection, hyaluronidase must be:

• in the practice, not "available to buy if needed";
• in date and stored according to the manufacturer;
• with a professional trained to use it, who knows the current guidelines;
• accompanied by an allergy assessment, since the enzyme itself can cause a reaction.

Keep in mind that hyaluronidase acts on hyaluronic acid. Other products, such as collagen biostimulators, are not reversed by it, which weighs on product choice in high-risk regions.

Ptosis from botulinum toxin

Botulinum toxin acts on muscle contraction. When it spreads to unintended neighboring muscles, it can cause:

• eyelid ptosis: drooping of the upper eyelid, linked to injections in the glabella and the periorbital region;
• brow ptosis: drooping of the brow, linked to injections in the forehead;
• expression asymmetry: uneven smile or eyebrows.

These effects are temporary and tend to resolve as the toxin effect wears off. The patient should be told to contact the professional who injected, who assesses and decides on supportive measures. Dilution, volume, points and aftercare are clinical decisions, in line with the package inserts and guidelines.

What should a complication protocol in the practice include?

A complication protocol is the set of supplies, roles and steps the team has already agreed on before any problem arises. Items that usually belong in it:

How can you reduce risk before injecting?

Prevention starts at the consultation:

• Complete medical history: allergies, medications, autoimmune diseases, previous procedures (including unknown products), pregnancy and breastfeeding, active infections.
• Assessment of the area: skin, inflammation, recent procedures, individual anatomy.
• Realistic expectations: patients with misaligned expectations tend to ask for excessive volume, which raises risk.
• Informed consent: risks explained in plain language, including rare and serious ones.
• Before photos: see standardized clinical photography.
• Staged planning: less volume per session and reassessment.

Where does Harmy fit into safety?

Harmy is a planning and communication tool. The projection is an illustrative simulation made on the frontal photo and does not assess anatomy, vessels, plane or technique. It does not replace clinical assessment and does not tell you whether an area is safe for that patient.

What it can do for safety is indirect: by showing the effect of moderate volumes, it helps align expectations and discuss staged planning instead of a large volume in a single session. The history also keeps the before photo and the plan by area, which are useful for reviewing what was proposed. The simulation is illustrative, not a promise of results.

Practice safety checklist

1. Hyaluronidase in the practice, in date.
2. Complication kit assembled and checked regularly.
3. Written protocol, known to the team.
4. Reference contacts for emergency and ophthalmology at hand.
5. Complete medical history and informed consent before every procedure.
6. Standardized before photos.
7. Record of product, lot, volume, area and instrument.
8. Written instructions to the patient about warning signs and a contact channel.

For the map of the areas and where vascular risk is higher, see the overview of injection areas.