Fillers are injected into either fine wrinkles or deeper folds or other tissues. Collagen and Restylane are the most common agents for fine wrinkles; Radiesse, Sculptra, and fat, for the deeper folds.A very fine needle is used to inject the filler directly into the wrinkles. Collagen numbs as it is injected, but Restylane and Radiesse do not contain anesthetic. For this reason, when I fill wrinkles in the center of the face or make lips larger I first numb the nerves to the cheek and chin. Through four injections, about 80 percent of the area around the mouth can be numbed. Sometimes, I numb the skin with EMLA anesthetic cream.After filler injections there are little red pinpoints and bruising from the needles. These spots can be immediately covered with makeup. It may take up to two weeks for all of the bruising to resolve. Makeup can be applied the next day, but the swelling will last about two days.When filler is injected into fine wrinkles, it is deposited in ribbons and blobs under the skin. The surgeon flattens the material with massage. If lumps are felt later, the patient can smush the gel with her finger. This step is important, because the blobs and ribbons will be camouflaged by swelling for a few days. Since hyaluronic acid absorbs water, wrinkles actually further improve in the days following injection. A typical hyaluronic-acid wrinkle-filling session takes thirty to forty-five minutes. The immediate result usually generates a ‘‘wow’’ from the patient.The RisksWhile wildly popular, these injections are not without risk. Collagen injections have a high chance of causing allergic reactions. Skin tests are required prior to injection. Repeated collagen injections may lead to the development of diseases similar to rheumatoid arthritis. Allergan recommends that no more than an ounce be injected per year. Allergic reactions are much less likely with the newer fillers.More important, the semisolid wrinkle fillers can be accidentally injected into blood vessels. When this happens, disaster looms. Around the eyes, nose, forehead, nasolabial folds, and even the lips, blood vessels link the skin with the eyeball and even the brain. If filler gets in these blood vessels, the result is immediate and permanent blindness. At least forty-three cases of blindness have been reported from injections around the eyes. If the material floats into the brain, a stroke can result. In other areas of the face, the consequences are not as severe, but loss of skin can result. The most common area of skin loss is between the eyebrows: the material mechanically blocks the blood vessels, resulting in the death of tissue in the affected area. Liquids such as Botox cannot occlude the blood vessels and therefore will not result in this problem.Surgeons take special precautions to avoid injecting into blood vessels. Ice and anesthetics with epinephrine shrink the blood vessels, and the doctor injects only while withdrawing the needle. Some physicians make a tiny stab in the skin and use a blunt needle to place the filler, further limiting the chance of injecting into a vessel. The fillers are injected using minimal force. Many doctors simply will not take the risk and will not inject around the eyes. As more injections are performed by less-trained people, disasters will be more common.Any injectable material can activate herpes infections. Patients who have herpes sores should receive an antiviral such as Valtrex before and after the injection. And injections should not be performed during an acne breakout.When fillers are injected, they eventually break down and are absorbed by the body. No one knows what happens if they are exposed to different types of lasers or radiofrequency energy. We may be in for some surprises. Until we know better, I recommend not lasering areas that have been filled. Laser first, then fill.The Bottom LineSo many fillers are available that it can be confusing for both doctors and patients. Patients should be sure that their surgeon injects only materials approved by the FDA or an equivalent agency. My own treatment regimen is fairly simple. When wrinkles are above the midnose, I usually use Botox or peeling or lifting procedures. I inject fillers around the eyes only sparingly. In the nasolabial folds, I prefer fat. If the patient wants a filler from a bottle, I choose Radiesse for the deep folds and Restylane for the superficial wrinkles. For other wrinkles on the face, I prefer Restylane. Stay tuned, however; the field is changing rapidly.