1. Overfilling during cheek augmentation
Hyaluronic acid used for contouring and filling possesses a certain degree of firmness. Injecting it over a large area or in excessive amounts may lead to facial stiffness and unnatural expressions.
2. Mismatched injection depth and product
For contouring and filling, hyaluronic acid should be injected into the deep dermis layer. For sculpting procedures like rhinoplasty, it may even require placement at the periosteal layer.Highly cross-linked, large-molecule hyaluronic acid that resists dispersion should be selected. Professional massage post-injection is essential to aid shaping and ensure even distribution.
Hydrating injections, however, involve superficial placement and require only easily dispersible, readily degradable small-molecule hyaluronic acid with low or no cross-linking. Otherwise, the skin cannot tolerate it, leading to hard lumps that cause uneven, stiff, and unnatural skin texture in the treated area.
3. Severe Inflammatory Reactions
Some individuals notice ideal results after their first hyaluronic acid injection. However, after several follow-up treatments, the injection site may appear unnatural or develop small lumps.
This occurs because hyaluronic acid is a foreign substance that does not permanently reside in the body; it is metabolized and gradually lost. The body's immune system responds to this process by breaking down and metabolizing the injected hyaluronic acid, triggering an inflammatory reaction.
Repeated hyaluronic acid injections cause frequent inflammatory reactions in the treated tissue, leading to a loss of natural appearance—one reason why many people notice unnatural facial features after multiple injections.
However, the injector's technique and the individual's unique physiology can also influence inflammatory reactions, so this cannot be generalized.