Antibacterial soap

Household setting

Non-antibacterial plain soap

Regular hand washing with non-antibacterial plain soap removes bacteria and viruses by physical/mechanical means. Plain soaps act as a detergent to help remove loosely adherent bacteria and viruses; microorganisms are not actually killed by these products.

Antibacterial soap

Antibacterial soaps for household use generally contain the active ingredient triclosan at concentrations between 0.1% and 0.45% weight/volume. Triclosan has varying effectiveness across bacterial and fungal species, and is less effective against viruses. A related compound, triclocarban, is used in antibacterial bar soaps.

Laboratory-based studies have shown triclosan at high concentration (1.0% weight/volume or higher) can reduce bacterial counts on the hands compared with plain soap.

However, community-based studies have shown that triclosan, at usual household concentrations of 0.1%-0.45% weight/volume, is generally no more effective than plain soap in reducing bacterial levels on the hands or in reducing infectious illnesses. Interestingly, even in studies conducted in areas with high rates of infectious illnesses, such as squatter settlements in Pakistan, antibacterial soaps offered little benefit compared with plain soap.

As most community infections are viral, the lack of a clear benefit for antibacterial household soap is not unexpected. However, even when examining the incidence of bacterial infections, such as impetigo, triclosan provided no benefit over plain soap.

Adverse effects of antibacterial soap in household settings

Dermatological adverse effects of triclosan

• Contact allergy to triclosan is very uncommon. In one study of patients with suspected contact dermatitis with unknown cause, less than 1% of the patients had positive reactions to triclosan.
• The potential for triclosan to cause irritant contact dermatitis is also very low, particularly at concentrations used in household soap.

Antibiotic resistance

Triclosan works in a similar way to the antibiotic isoniazid, which has raised the question of whether widespread community use of triclosan may play a role in the development of antibiotic-resistant bacteria. Several laboratory-based studies have supported this theory, while community-based studies have not demonstrated evidence of antibiotic resistance with the use of triclosan-containing soap over a one-year period.

Further research is needed to assess whether the increasing community use of triclosan is changing antibiotic-resistance patterns in bacteria over the longer term.

Other concerns

Other concerns include the potential of triclosan to react with chlorine in tap water to form chloroform gas (a potential human carcinogen) and dioxins (harmful to the human endocrine system and the environment). The actual risks posed by these reactions, outside the laboratory setting, are currently unclear.

Summary

The benefits of household use of triclosan over plain soap have not been clearly proven and the data on its potential risks are conflicting. Some experts are now recommending reducing or even discontinuing the use of antibacterial household soap.

Healthcare settings

Healthcare settings often use antimicrobial/antiseptic hand wash products, such as chlorhexidine and high concentration triclosan. These products are effective against many bacteria, fungi, and viruses and often have residual antimicrobial activity on the skin that persists for some time after completion of hand washing. In healthcare settings, antibacterial soap is likely to be more effective than plain soap, although some of the evidence is conflicting.

Alcohol-based hand rubs are gaining popularity in healthcare settings as they are at least as effective as traditional hand washing with antimicrobial hand wash products in reducing bacterial counts on skin and in reducing hospital-acquired infections. Furthermore, hand rubs are less irritating to the skin than traditional hand wash products.

Adverse effects of antibacterial soap in healthcare settings

• Irritant contact dermatitis is a particular problem amongst healthcare workers due to frequent hand washing, as this removes natural oils and emollients. Hand care is very important for healthcare workers.
• The higher concentrations of triclosan used in healthcare settings may increase the risk of irritant and allergic contact dermatitis, although reactions are still uncommon.
• Chlorhexidine is generally well-tolerated, however repeated or prolonged skin contact may cause irritation in sensitive individuals. The frequency of skin irritation is also concentration-dependent. Although allergic reactions to chlorhexidine are rare, there have been isolated reports of allergic contact dermatitis and anaphylaxis.