An agent capable of inducing functional derangements or organic lesions in tissues.
A substance which can irritate.
Stimulus, often physical, that causes irritation or inflammation.
Any material that causes irritation of a tissue, ranging from nettles (causing pain and swelling) to tear gas (causing watering of the eyes). Chronic irritation by various chemicals can give rise to dermatitis.
Any substance that produces irritation in a tissue. Examples are: stinging nettles, which cause pain and swelling; certain insect bites or stings which do the same; and anti riot gases such as CS gas, which cause the eyes to water and provoke coughing. Regular, unprotected handling of certain substances for example, oil can irritate the skin and cause dermatitis. Some people are more sensitive than others to the effect of irritants; sometimes an irritant will produce an allergic reaction and in serious cases anaphylaxis, which may require medical treatment.