This is a medical injection and it carries real risk. Bruising is the commonest event, and it is more likely and more visible around the eye, where a mark can take the better part of a week to fade. Swelling and tenderness across the injected field belong to the first day or two, along with redness and small palpable points where the needle went in.
Nodules are the risk that deserves the most attention with any collagen stimulator, and they are the reason placement depth and technique matter so much. Firm lumps can form where particles clump or sit too superficially, they may be felt before they are seen, and they can surface weeks after the appointment, well past the day you were treated. Some settle with time and management; some need active treatment; and unlike a hyaluronic acid filler, this material is not reversible with an enzyme injection. Less commonly, patients see infection at an entry point, pigment change following inflammation in skin that pigments readily, prolonged swelling, asymmetry between the two sides, or a reaction to an injected component.
Tell the clinic everything before you are treated: your full medical history, all medication and supplements, every previous injectable and its approximate date, any implant in the area, and any lump you have ever developed after a cosmetic injection. Afterwards, follow the aftercare instructions you are given, keep the field clean, avoid strong sun on it while it settles, and contact the clinic if a lump appears or persists, if pain or redness increases after the second day, or if anything spreads outward from an injection point. A resident medical director is in the building during opening hours.