Thank you for your question.Any type of filler injection, including the use of Juvederm, has the potential for inadvertent vascular injection. The fact that the skin immediately turned purple gives a high index of suspicion that this may have occurred, however, it may also be from compression of the vessels causing a stoppage of blood flow by the thickness of the medicine externally. If left untreated, the skin and area supplied by the involved vessel may become necrotic. If skin is involved, this may lead to bad scars. If retinal vessels are involved blindness could result. This is a true emergency situation and needs to be treated immediately. Direct heat, nitroglycerin paste, injection with hyaluronidase immediately are all indicated. The fact that you are reporting this and it was recognized some time later, indicates there may be adequate collateral circulation and it may resolve without incident, but may take some time. If discovered immediately or within the first few minutes, treatments are more likely to be successful in correcting or reversing the process. The same supportive treatments done later are less likely to be effective, or may resolve spontaneously. In any case, see your injector immediately and get expert advice and treatment.