Swelling after Restylane injections is always a possibility. However, you should know that this will be different from one person to another, as our bodies will be reacting differently to the treatment. Swelling is normal after Restylane injection treatment, as the skin is being injected and penetrated by fillers, it may cause slight irritation thereby causing the swelling. This may last for a couple of weeks, but again, this is perfectly common.Swelling can be managed by ensuring that your head is elevated when sleeping so that fluids will not pool in your head. You may also use ice packs as these may lessen swelling. On the other hand, you will need to avoid some herbs and medications that serve blood thinners prior undergoing Restylane treatment. For your case though, you need to know that doing Restylane injection in the area under the eyes is deemed as an off label procedure. Nevertheless, it can still be done by skilled injectors. Some swelling could happen since this area is very sensitive. Do consult your board certified plastic surgeon for this kind of treatment area so as to avoid possible after effects.