Antiseptics

What is an antiseptic?

An antiseptic is a chemical agent that slows or stops the growth of microorganisms on external surfaces of the body and helps to prevent infection.

Antiseptics should be distinguished from antibiotics, which destroy microorganisms inside the body; and from disinfectants, which destroy microorganisms found on inanimate (non-living) objects. Antiseptics can be referred to as skin disinfectants.

A 1 in 10,000 dilution of potassium permanganate ready to use

Chlorhexidine wash

What are antiseptics used for?

When the skin or mucous membranes are damaged or breached, an antiseptic can be used to cleanse the area and reduce the chance of infection by normally occurring microorganisms. Antiseptics kill, inhibit, or reduce the number of microorganisms by mechanical removal or chemical activity.

Antiseptics are commonly used for:

• Hand washing — chlorhexidine gluconate and povidone-iodine solutions are often used in hand rubs in hospitals and other health care settings. Alcohol in concentrations > 60% will destroy pathogens such as the SARS-CoV-19 virus. 
• Preoperative skin disinfection — antiseptics can be used to clean intact skin prior to an operation (to reduce the risk of surgical site infections) or a procedure such as intravenous (IV) cannulation.
• Mucous membrane disinfection — antiseptic irrigations may be instilled into the bladder, urethra, or vagina to cleanse the cavity prior to a medical procedure such as catheterisation.
• Preventing and treating infected skin — antiseptics can be used to clean contaminated cuts, wounds, abrasions, burns, and bites, including in some skin conditions such as acne and atopic dermatitis (eczema). See also: Wound cleansers.
• Treating oral infections — mouth and throat infections can be treated with antiseptic throat lozenges, gargles, and mouthwashes.

Many agents can be used as both an antiseptic and a disinfectant, depending on the concentration. For example, hydrogen peroxide 6% solution is used for cleansing wounds, while stronger solutions (>30%) are used in industry as bleach and oxidising agents.

Types of antiseptics

Antiseptics can be classified according to their chemical structure. The following table lists commonly used antiseptic groups and some examples.

Table 1. Antiseptic groups and examples

What are the precautions when using antiseptics?

Table 2. Antiseptic contraindications and precautions

What are the benefits and disadvantages of antiseptics?

Antiseptics reduce the number of microorganisms living on the skin, in wounds, and in mucous membranes. They can be particularly useful when an individual needs to cleanse the skin quickly. Many antiseptics are available to buy over-the-counter at pharmacies, making them convenient and easily accessible.

Antiseptics can cause severe skin irritation or chemical burns. Skin reactions may include erosions, ulcers, vesicles, and scarring. Allergic reaction such as immediate type 1 reactions, anaphylaxis, and allergic contact dermatitis may occur. 

There is also the risk of product contamination from repeated use of topical antiseptics. This can lead to further problems such as localised or systemic infections when the contaminated product is reapplied to open skin, a wound, or a burn.  

Alcohol-containing products are flammable and need to be kept away from fire at all times. 

Antiseptic safety and efficacy

The effectiveness and complete safety of antiseptics have proven difficult to establish. 

In September 2016, the US Food and Drug Administration (FDA) issued a final rule establishing that over-the-counter consumer antiseptic wash products containing any of the nineteen ingredients listed could not be marketed. This included triclosan and triclocarban. The rationale cited being:

• Lack of evidence that antibacterial wash is more effective than plain soap and water at preventing illness.
• Prolonged household use of antibacterial products such as antibacterial soaps may contribute to antibiotic resistance.

In December 2017, the FDA further ruled that 24 ingredients found in antiseptic products (including triclosan) were generally not recognised as safe and effective (often due to inadequate data). These required regulatory approval for marketing from December 2018 as new drugs. A decision was deferred on a further six ingredients (benzalkonium chloride, benzethonium chloride, chloroxylenol, ethyl alcohol, isopropyl alcohol, and povidone-iodine).

It is important to note that antiseptics may impair wound healing if they kill skin cells that are involved in the healing process, such as fibroblasts. Routine use of antiseptics for cleansing clean wounds is no longer recommended. Pus and necrotic tissue can also inactivate some antiseptics, reducing their efficacy.  

Antiseptics should also be differentiated from antibiotics. Antiseptics only reduce microorganisms on the surface of the tissue whereas antibiotics may be needed if infection exists within the tissues.

What are the side effects and risks of antiseptics?

Individuals using antiseptics need to do so correctly. Strong antiseptics should be appropriately diluted before being applied to the skin, as concentrated products may cause chemical burns or severe irritant contact dermatitis. Prolonged contact with dilute antiseptics can also cause erosive contact dermatitis, as described with chlorhexidine-impregnated dressings.

Antiseptic products should not be used for more than one week on acute wounds. Chronic wounds with no improvement after 10 to 14 days should be also referred for medical review.

Additional reasons to stop using an antiseptic and to seek medical attention include: 

• The affected area has not healed or improved
• There is a large wound, deep cut, burn, or abrasion embedded with particles that won’t wash away
• Injury due to a human or animal bite.

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.

Side effects of common antiseptics are listed in the table below. Emollients and moisturisers are recommended after use if the hands are dry or develop contact dermatitis due to antiseptic use.

Table 3. Antiseptic side effects