What are antiseptics?
Antiseptics are chemical agents that slow or stop the growth of micro-organisms (germs) on external surfaces of the body and help 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.
Types of antiseptics
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.
|Alcohols||Ethyl alcohol 70%
Isopropyl alcohol 70%
|Quaternary ammonium compounds||Benzalkonium chloride
Eye drop preservative
|Chlorhexidine and other diguanides||Chlorhexidine gluconate
|Pre-op skin disinfectant
|Antibacterial dyes||Proflavine hemisulphate
Treat wounds and burns
|Peroxides and permanganates||Hydrogen peroxide solution
Potassium permanganate solution
Gargles and mouthwashes
|Halogenated phenol derivatives||Chlorocresol
Hexachlorophane/hexachlorphene (no longer available)
Medicated soaps and solutions
|Quinolone derivatives||Hydroxyquinoline sulphate
Potassium hydroxyquinoline sulphate
|Miscellaneous||Burow's solution (aqueous solution of aluminium acetate)
Uses of antiseptics
Antiseptics are 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 what are usually harmless micro-organisms. However, when the skin or mucous membranes are damaged or breached in surgery, antiseptics can be used to disinfect the area and reduce the chances of infection. It is also important that people whom are treating patients with wounds or burns adequately wash their hands with antiseptic solutions to minimize the risk of cross infection.
Antiseptics are used for:
- Handwashing – chlorhexidine gluconate and povidone iodine solutions are often used in hand scrubs and hand rubs in hospital settings.
- Pre-operative skin disinfection – antiseptics applied to the operation site to reduce the resident skin flora. Caution should be used in facial use of solutions containing chlorhexidine, as these can injure the eye causing keratitis.
- Mucous membrane disinfection – antiseptic irrigations may be instilled into the bladder, urethra or vagina to treat infections or cleanse the cavity prior to catheterisation.
- Preventing and treating infected wounds and burns – antiseptic preparations are available over-the-counter from your pharmacist to treat minor cuts, abrasions and burns.
- Treating mouth and throat infections – dequalinium chloride has both antibacterial and antifungal properties and is the active ingredient in antiseptic throat lozenges.
Precautions when using antiseptics
Strong antiseptics should be diluted before they are applied to the skin, as concentrated products including chlorhexidine may cause chemical burns or severe irritant contact dermatitis. Prolonged contact with diluted antiseptics can also cause erosive contact dermatitis, as described with chlorhexidine-impregnated dressings.
Antiseptics bought from the pharmacy should not be used for more than one week. If the affected area has not healed or improved in that time you should stop using the antiseptic and see your doctor. Large wounds, deep cuts, burns larger than a small red spot, scrapes imbedded with particles that won’t wash away, animal bites and eye injuries should be treated by your doctor. Do not use antiseptics to treat sunburn or existing skin infections. Remember that antiseptics only reduce 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.
What about antibacterial soaps?
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:
- There is no scientific evidence that antibacterial washes are any better than soap and water in preventing the spread of germs
- Household use of antibacterial ingredients may do more harm than good over the long-term, such as promoting bacterial resistance (see MRSA)
Hand sanitisers containing at least 60% alcohol can be used, if soap and water are not available.