Antiseptics and disinfectants are both used to kill or to limit the growth of bacteria and other microorganisms. The key difference between them is the place in which they they are used. Antiseptics are used on exposed portions of the body, often, but not always, at the site of a wound or surgical incision, in order to prevent infection. Disinfectants are used on other surfaces, ranging from operating room surfaces to kitchen counters, in order to destroy potentially dangerous microbes.
The use of both disinfectants and antiseptics is a fairly recent addition to medical practice. The miasmatic theory of disease, which held that diseases were caused by foul environmental influences rather than microorganisms, remained widely accepted into the middle of the 19th century. The medical establishment proved reluctant to change standard procedures, even in the face of overwhelming experimental evidence.
Early pioneers in research on antiseptics and disinfectants, such as Ignaz Semmelweis, who studied mortality among mothers treated without proper antiseptic procedures, quickly noted that basic sanitary precautions greatly reduced many of the risks associated with medical treatment. Although doctors were slow to adopt his advice, eventually, his view prevailed. Joseph Lister became the most successful proponent of the use of antiseptics and disinfectants, and his work sufficed to gradually shift standard medical practice.
Antiseptics and disinfectants both work to kill microbes, but antiseptics must also cause little or no harm to the tissues of the body. Hydrogen peroxide and alcohol are among the most common antiseptics used in both medical and household applications. They are typically used to clean the skin before an incision is made, to eliminate any potentially dangerous microbes on the skin's surface. Antiseptics may also be used to treat surface cuts or abrasions to kill any microbes that might have already entered a wound, although this process can slightly damage the tissue and cause discomfort as well.
Disinfectant agents, unlike antiseptics, need not be safe for use on living tissue. Many common household substances have excellent disinfectant properties. A simple solution of bleach is extremely effective in killing most microbes, and bleach is widely used for this purpose, both in medical facilities and in ordinary household applications. When using a chemical agent as a disinfectant is not desirable, other options exist, including the use of ultraviolet light or radiation, both of which are generally unsuitable for use on living tissue but can be very effective in eliminating microbes.