Conjunctivitis is an inflammation of the membrane that covers the eye and lines the inner surface of the eyelids. The membrane is called the conjunctiva. Conjunctivitis can be caused by irritants, by allergy and by infection. Irritants would include smoke, soap, hairspray, cosmetics, chlorine in swimming pools etc. Allergic causes would include grass and other pollens. The third category I have listed would include infection, which could be due to bacteria or viruses. This form of conjunctivitis is indeed contagious and can be spread by contaminated hands, face cloths or towels. It can also be transmitted through contaminated eye make up, false eyelashes and contact lenses.