The incidence of ischemic complications in hyaluronic acid (HA) fillers is estimated to be around 0.3%. To prevent tissue necrosis, it is essential to have a comprehensive understanding of facial vascular anatomy and to use a meticulous technique. Necrosis can occur due to arterial or venous obstruction. Late complications, which appear after 2-6 weeks, include late allergic reactions, chronic inflammation and infection, granulomas, migration of fillers, loss of function, telangiectasia, and hypertrophic scars.
To avoid infection, the injection site should be thoroughly disinfected and degreased, and the injection should not be done with makeup. If an infection does occur, it should be treated immediately with antibiotics and usually responds quickly. The formation of granulomas is unpredictable and depends on the material used. Particulate material is more likely to induce a macrophage reaction, particularly permanent fillers, but also poly-L-lactic acid (PLLA) whose particles have a crystalloid structure.
The probability of granulomas increases with the surface-volume ratio of filler particles and their shape with sharp edges. Quality hyaluronic acid fillers are unlikely to cause this effect. Silicone oil causes a slightly different reaction called siliconoma with lymphocytic infiltrates. Permanent fillers based on acrylate gels appear homogeneous but are actually particulate.
The most serious complications are vascular; vascular occlusions can lead to necrosis (tissue death), scarring and even blindness. In fact, dermal fillers have already resulted in 98 reported cases of blindness (Beleznay et al., 201). Other side effects reported in clinical trials include facial weakness, drooping of the eyelid and drooping of the eyebrows. Rarely, injections have caused double vision, dry eyes, or difficulty swallowing or breathing.
It is not recommended to inject botulinum toxin products for cosmetic purposes during pregnancy or lactation.
