Why are my lower eyelids puffy?

The swelling in the lower eyelids is related to the normal fatty tissues that surround the eyes. Fat loves fluid. An irritation, an allergy, an infection amongst other things can cause swelling (fluid uptake) by the fat around the eyes. As we mature this fatty tissue can move forward causing bagginess to the eyelids. At this point cosmetically we begin to look tired and blepharoplasty (eyelid lift) is sometimes the answer.