(I) Anything that irritates the eyes can also irritate the eyelids and cause swelling. (II) The most common irritant is an allergy, which can make one or both lids crinkled or swollen. (III) Allergic reactions may be caused by medications instilled into the eyes, such as eyedrops; other drugs or cosmetics; or pollen or other particles in the air. (IV) Insect stings or bites as well as infections from bacteria, viruses, or fungi can also cause the eyelids to swell. (V) In fact, tears are salty fluid that continuously bathes the surface of the eye to keep it moist.