Injection Site Complications
The most prevalent complications of soft tissue filler injection are the injection site adverse effects including bruising, edema, pain, erythema, and ecchymosis (Figure 1). These side effects are mostly transient and mild, lasting a few days.3 Bruising is usually observed after injection of the filler material into the dermal layer when given by fanning or threading method. The occurrence of bruising can be reduced by slow injection of the filler material and, if occurred, cold compresses should be used.4 Bruising typically disappears in a week’s time. If the patient is on anticoagulant therapy, it should be discontinued at least 7–10 days before the procedure after consulting with the treating physician. The injection related pain and swelling can be minimized by application of ice prior to injection, the use of small gauge needle or blunt cannulas, and the combination of fillers with of local anesthetics, typically lidocaine. Cold compresses and NSAIDs can help in ameliorating the pain and swelling after the procedure. In severe cases, short course of oral steroids may be needed along with the NSAIDs. Mild erythema is also commonly seen after the injection but persistent erythema may require a short course application of moderate potency topical steroids. Vitamin K cream has been reported as beneficial in the management of purpura.5
Dysesthesia, Anesthesia, And Paresthesia
An inadvertent trauma, direct injection into the nerve, or compression of the nerve by the filler material can cause nerve damage that may lead to dysesthesia, anesthesia, or paresthesia, which may be transient or, rarely, permanent. The most commonly affected nerve during filler injections is the infraorbital nerve, but rarely, Bell’s palsy and marginal mandibular nerve damage has been reported.6,7 A thorough knowledge of nerve anatomy is required before injection to prevent such adverse effects.
Inappropriate Injection Technique-related Complications
A filler should be placed in the appropriate tissue layer. Inappropriate injection technique and too-high volumes can cause side effects like visible implants, palpable nodules, over-, or under-correction. Lumps and bumps at the site of injection are some of the most prevalent side effects seen with filler injections (Figure 2). They may be non-inflammatory, inflammatory, or infectious. Early onset lumps are usually due to suboptimal injection techniques like excess filler injection or too superficial placement of the injected material. Persistent non-inflammatory lumps are usually due to overcorrection and superficial injection and usually respond to massage, but in some cases, needle aspiration, drainage, and intralesional hyaluronidase injections may be required.8
Too superficial filler injection can lead to a bluish discoloration known as Raleigh scattering or Tyndall phenomenon, and sometimes due to hemosiderin deposition due to intradermal bleeding during the injection (Figure 3). It may persist for a longtime, if left untreated. Hyaluronidase injection is the preferred treatment option for this discoloration if a hyaluronic filler was used. Drainage of the filler is the recommended treatment of nodules caused by polymethyl methacrylate (PMMA) injections. A combination of intralesional neodymium-YAL laser and drainage seems to be even more effective.9 Superficial injection of fillers containing calcium hydroxylapatite or poly-L-lactic acid can cause small, whitish nodules on the skin surface. Superficial silicone injections may lead to fibrosis and foreign body granulomas formation termed siliconomas presenting as nodules.10