What Causes Under-Eye Bags?

Under-eye bags—those puffy, sometimes shadowed or swollen areas beneath the lower eyelids—are a common cosmetic concern, but they also reflect underlying anatomical and physiological changes. The primary cause is age-related weakening of the orbital septum, a thin fibrous membrane that normally holds fat pads in place behind the eye socket. As this structure loses elasticity over time, orbital fat herniates forward into the lower eyelid, creating visible fullness or bulging.

Additional contributing factors include chronic fluid retention, often exacerbated by high-sodium diets, alcohol consumption, or insufficient sleep; allergic rhinitis or other inflammatory conditions that increase vascular permeability and local edema; and genetic predisposition—some individuals inherit thinner skin, more prominent fat compartments, or weaker connective tissue support in the periorbital region. In rare cases, persistent or asymmetric under-eye swelling may signal systemic conditions such as thyroid eye disease, renal dysfunction, or cardiac insufficiency, warranting clinical evaluation.

It’s important to distinguish true fat prolapse (structural) from transient edema (functional). While topical treatments and lifestyle modifications may temporarily improve puffiness related to fluid shifts, surgical interventions like transconjunctival blepharoplasty address the root anatomical cause by repositioning or conserving herniated fat rather than simply removing it—a technique now favored for preserving natural contour and preventing hollowing.