Swelling under the eye, or edema, is commonly caused by normal aging, hypothyroidism, allergies, infection, or lifestyle choices. Sometimes hormones related to pregnancy or menstruation may cause eye swelling. Eye puffiness may be treated with cold compresses or taking preventative action such as lifestyle changes. Occasionally, those with eye swelling seek surgical intervention.

As people age, the delicate skin around the eyes becomes thinner. It also tends to lose its elasticity. Sometimes the fat under the skin begins to bulge or fill out the less elastic tissue. This can lead to long-term swelling or puffiness under the eyes. It may be treated with cosmetic surgery.

Hypothyroidism may be a cause of overall facial swelling, including swelling under the eye. This is caused by mucopolysaccharides, or long chains of sugar molecules, pulling fluid into the tissue under the eye. If swelling under the eye is chronic, and if a person suffers from other symptoms of hypothyroidism such as cold intolerance, lethargy, and/or weight gain, a thyroid test might be warranted.

Allergies are sometimes responsible for eye swelling. People can have allergic reactions to substances they previously tolerated. Allergic reactions may occur with exposure to animal dander, foods, plants, and many other environmental agents. Antihistamines are often the treatment of choice for common allergens.

Blepharitis, or inflamation of the eyelids, is an infection that may cause swelling under and around the eyes. The symptoms of blepharitis may include itching, excessive tearing, feeling as if something is in the eye, or burning. Treatment may include antibiotic ointment or drops.

Conjunctivitis may be viral, bacterial, or due to an allergen. This is a very contagious illness that can cause swelling under the eye, redness in the white of the eye, or itching or burning sensations. This illness is usually treated with antibiotic ointment or eye drops.

A stye may cause swelling under the eye. It is a bacterial infection in which the oil glands at the base of the eyelashes become inflamed. Styes resemble small bumps similar to acne. These bumps should not be popped because styes are contagious. They are generally treated with antibiotics.

Lifestyle choices are another common cause of swelling under the eye. Oversleeping, sleep deprivation, or eating a high-salt diet might cause fluid retention throughout the body including under the eye. Alcohol tends to dehydrate the body and may trigger under-eye puffiness. Getting enough sleep and eating or drinking in moderation are necessary steps to avoid lifestyle-related eye puffiness.

Hormonal shifts during menstruation and pregnancy may be contributing factors of swelling under the eye. During hormonal fluctuations, the body may retain fluid. In addition to common premenstrual abdominal bloating, the skin under the eyes might become slightly swollen. People can treat this type of puffiness by keeping themselves hydrated. Some beauty experts recommend putting used tea bags, cucumber slices, or cold compresses over the eyes for several minutes. These will cool the area, thereby causing the blood vessels to shrink.