Filler injections belong to the most frequently performed noninvasive beautifying procedures. When done correctly they are generally well tolerated. However, a number of factors, such as poor filler quality, and particularly host as well as user dependent filler reactions may lead to unwanted effects. These may be early, late, or delayed events with characteristics for each of them. Temporary fillers almost invariably cause temporary side effects whereas those of permanent fillers may last forever. Some fillers are notorious for their poor safety profile; for example, silicone is banned in the European Union and the United States but nevertheless used by many practitioners and beauticians. Many fillers can be identified in histopathologic sections allowing specific measures to be instituted.