Many cosmetics, for example nail polish, can cause a contact allergy (an allergic reaction caused by physical contact with a particular substance) of the eyelids. Other substances that may cause contact allergy of the eye or eyelids include antibiotics, particularly neomycin, and preservatives such as thiomersal, which is found in eye drops.

If a person experiences an allergy to eye drops, often they notice an initial improvement of the condition for which the eye drops were prescribed, only to find their condition starts to get worse after a short time. Stopping the use of the eye drops is the only answer.

To ease symptoms arising from contact allergy, bathe your eyes with cooled saline (salt water). This will help soreness by washing out excess mucus and allergen.

Some plants can cause severe eye allergy. The common ones found in Australia that can do this are Grevillea (¡®Robyn Gordon¡¯), African violets and some types of bulbs. Since the Rhus tree has been declared a noxious weed, the number of cases of contact allergy arising from it have declined, as have those from privet, another plant that can cause allergic reactions in susceptible people.

To diagnose an allergy to a particular plant, your doctor will need to take a careful history and perform patch testing.