Dermatology Made Easy is based on the most popular topics from DermNet NZ's vast array of material. The book combines the essential focus of the ‘Made Easy’ book series with the authority and knowledge base of DermNet NZ's unparalleled resources.
Author: Vanessa Ngan, Staff Writer, 2005.
An antiseptic is a chemical agent that slows or stops the growth of micro-organisms (germs) on external surfaces of the body and helps to prevent infections. Antiseptics should be distinguished from antibiotics that destroy micro-organisms inside the body, and from disinfectants, which destroy micro-organisms found on inanimate (non-living) objects. However, antiseptics are often referred to as skin disinfectants.
Most chemical agents can be used as both an antiseptic and a disinfectant. The purpose for which it is used is determined by its concentration. For example hydrogen peroxide 6% solution is used for cleansing wounds, while stronger solutions (> 30%) are used in industry as a bleach and oxidising agent.
Antiseptics can be classified according to their chemical structure. Commonly used antiseptic groups include alcohols, quaternary ammonium compounds, chlorhexidine and other diguanides, antibacterial dyes, chlorine and hypochlorites, inorganic iodine compounds, metals, peroxides and permanganates, halogenated phenol derivatives and quinolone derivatives. The following table lists some of the agents within these groups.
Quaternary ammonium compound
Chlorhexidine and other diguanide
Peroxide and permanganate
Halogenated phenol derivative
Antiseptic is mainly used to reduce levels of microorganisms on the skin and mucous membranes. The skin and mucous membranes of the mouth, nose, and vagina are home to a large number of micro-organisms (which are normally harmless).
Antiseptics are used for:
Strong antiseptic should be diluted before it is applied to the skin, as concentrated products including chlorhexidine may cause chemical burns or severe irritant contact dermatitis. Prolonged contact with diluted antiseptic can also cause erosive contact dermatitis, as described with chlorhexidine-impregnated dressings.
Antiseptic bought from the pharmacy should not be used for more than one week. Stop using the antiseptic and see a doctor if:
Do not use antiseptics to treat sunburn or deep skin infection. Remember that antiseptic only reduces microorganisms on the surface of the tissue and that antibiotics will be needed to treat infection within the tissues.
People with allergies of any kind should check with a doctor or pharmacist before using an over-the-counter antiseptic product. Some antiseptics can irritate the skin and cause allergic contact dermatitis. Chlorhexidine has been reported to rarely cause anaphylaxis.
In September 2016, the US Food & Drug Administration (FDA) issued a final rule establishing that over-the-counter (OTC) consumer antiseptic wash products containing certain active ingredients can no longer be marketed. Nineteen of these are listed, including triclosan and triclocarban. Regulators in other countries may follow with similar rulings. Reasons include:
Hand sanitiser containing at least 60% alcohol can be used, if soap and water are not available.
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