There can be several factors that can cause swelling of the eyelid. Usually, it is caused by an injury or trauma, or an allergic reaction to a particular allergen like pollen, dust, and certain specific food and drugs. Even allergies to certain chemicals used in eye makeup can cause an inflammation or swelling of the eyelid. In addition to these, some other possible causes are, bacterial infections of the eyes, blepharitis, conjunctivitis or pink eye, chalazion, stye, trichinosis, and ocular herpes.