What Is an Antiseptic?

Antiseptics are substances applied to the exterior of the body that kill or inhibit microbes and infective agents. Antiseptics can be effective against one or a combination of bacteria, fungi, viruses or other microorganisms. The discovery and development of antiseptic chemicals and principles began in the 19th century, and are today universally employed in developed countries.

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What Antiseptics Do

Antiseptics are compounds that are used to kill or counter microorganisms on and near the surface of the body. They are distinct from antibiotics and antiviral drugs, which work inside the body, and from disinfectants, which are chemicals applied to nonliving items and surfaces.

While antiseptics are widely assumed to kill infectious agents, they can also be effective as bacteriostatic compounds that prevent or greatly inhibit bacterial growth. By impeding or preventing further microbial growth, such antiseptics can put a time limit on an infection.

Antiseptic History

Because the role of germs in causing disease wasn't discovered until the late 1800s, the true medical importance of good hygienic practices was not widely understood until the 20th century.

The first implementation of antiseptic policies in a hospital setting occurred in the late 1840s in Vienna, Austria, pioneered by Dr. Ignaz Semmelweis, a physician trying to control his hospital's sprawling death rate.

On a hunch, Semmelweis required doctors who'd been near a dead body to begin washing their hands in a chlorine bleach solution before seeing patients. Patient death rates immediately plummeted, and without knowing exactly how or why, Semmelweis had successfully implemented the first infection control protocol in medicine.

Germ Theory

Semmelweis' findings were resisted by the European medical bureaucracy for decades. Only later, with discoveries by Louis Pasteur and the germ theory of disease, did doctors and scientists become aware that infection was caused by tiny microbes, and that if vulnerabilities in these microbes could be exploited, infections could be prevented.

Early Antiseptics

After Semmelweis's chlorine solution, the first widely tested antiseptics were based on alcohol, iodine and carbolic acid or phenol. Since then, the discovery and development of antiseptic substances has ballooned, with dozens of antiseptic chemicals now in regular use in medical, industrial, commercial and residential settings worldwide.

Since Semmelweis and Pasteur, antiseptic-based infection control has turned from an art of trial-and-error into an involved science of chemistry and microbiology.

Antiseptics in Action

Chlorhexidine is an ingredient in some mouthwashes and in hospital settings. Hydrogen peroxide solution is a longstanding antiseptic used in everything from mouthwashes to light wound cleansing. Various compounds of iodine are used in pre- and post-operative infection prevention around incisions or cuts. Alcohol remains one of the most common antiseptic chemicals for mouthwash and cut care.

Mechanisms of Action

All antiseptics interfere with crucial life processes of microorganisms. Benzylalkonium, for example, interferes with intracellular signaling and chemistry to the point that the cell membrane begins to disintegrate. Iodine compounds irreversibly deform, or denature, critical proteins in bacteria, starting at the cell membrane and moving inwards. Alcohol also denatures and destroys cell membranes. Some soaps and detergents cause bacterial cell membranes to lose integrity or denature critical proteins. Other antiseptics are believed to directly interfere with critical enzymes inside a microbe.