What concentrations of chlorhexidine gluconate are used for skin antisepsis and for surgical hand‑scrub in the operating theatre?

Chlorhexidine Concentration for Surgical Hand Scrub

For surgical hand scrubbing in the operating theatre, use 4% chlorhexidine gluconate scrub or 1% chlorhexidine gluconate with 61% ethanol as a waterless alternative. 1

Surgical Hand Scrub Concentrations

Traditional Scrub Method

• 4% chlorhexidine gluconate is the standard concentration for traditional surgical hand scrubbing with water and brush 1
• This concentration requires a 3-minute scrub application to achieve adequate antimicrobial reduction 1

Waterless Scrub Method (Superior Option)

• 1% chlorhexidine gluconate combined with 61% ethanol provides superior antimicrobial efficacy compared to 4% chlorhexidine alone 1
• This waterless formulation produces a 2.5-log reduction in bacterial flora immediately after a single application, increasing to 3.6-log reduction after repeated use over 5 days 1
• The combination product demonstrates significantly better microbial reduction (P <.05) than 4% chlorhexidine at most sampling intervals 1

Skin Antisepsis Concentrations (Different from Hand Scrub)

For Patient Skin Preparation

• 0.5% chlorhexidine in 70% alcohol is recommended for skin antisepsis before central neuraxial blockade and other procedures 2
• 2% chlorhexidine in 70% alcohol is used for general surgical site preparation and provides superior bacterial reduction compared to 0.5% concentration 3

Evidence for Concentration Selection

For skin antisepsis:

• 2% chlorhexidine/70% isopropyl alcohol reduces microorganisms more effectively than 0.5% chlorhexidine/70% isopropyl alcohol at 2 minutes post-application (P = .033) and after wound closure (P = .016) 3
• However, for neuraxial procedures specifically, 0.5% chlorhexidine in alcohol is preferred due to neurotoxicity concerns with higher concentrations, despite lack of convincing evidence of antimicrobial superiority of 2% over 0.5% 2

Critical Application Principles

For Hand Scrubbing

• The waterless 1% CHG/61% ethanol formulation requires no scrubbing or water, making it more practical and equally effective 1
• Traditional 4% CHG requires proper scrub technique with brush for 3 minutes 1

For Skin Preparation

• Always allow the antiseptic solution to dry completely before needle insertion or incision to prevent neurotoxicity and maximize antimicrobial efficacy 2
• Two scrubs with chlorhexidine are superior to one scrub, even when diluted to 0.4% concentration 4
• Diluting 2% chlorhexidine to concentrations as low as 0.4% does not affect antiseptic efficacy 4

Common Pitfalls to Avoid

• Do not confuse hand scrub concentrations (4% or 1% with alcohol) with skin prep concentrations (0.5-2% with alcohol) - these serve different purposes 2, 1
• Never allow chlorhexidine to contaminate neuraxial equipment - keep antiseptic solutions away from drugs and equipment used for spinal/epidural procedures 2
• Ensure complete drying - applying needles or making incisions before the solution dries reduces efficacy and increases neurotoxicity risk 2
• Avoid pouring chlorhexidine into gallipots on the same sterile field as neuraxial equipment, as splash can spread at least 40 cm and contaminate equipment 2