What are the proper concentrations, dosing, contraindications, and side effects of chlorhexidine (misspelled chlorocedin) for skin disinfection, oral rinses, and catheter care in adults and infants?

Chlorhexidine: Concentrations, Dosing, Contraindications, and Side Effects

Proper Concentrations and Formulations

For skin disinfection before invasive procedures in adults and children over 2 months, use 2% chlorhexidine gluconate in 70% isopropyl alcohol. 1

• This formulation has been confirmed as the most effective way of removing microorganisms from the skin surface before catheter insertion and during subsequent catheter care. 1
• For blood culture site preparation, chlorhexidine (with or without alcohol) reduces contamination rates by 56.5% compared to other antiseptics. 1
• The 0.5% chlorhexidine in 70% alcohol formulation is an acceptable alternative, particularly for central neuraxial blockade, given concerns about neurotoxicity with higher concentrations. 1
• Aqueous chlorhexidine solutions are less efficacious than alcohol-based products and should be avoided when possible. 1

Application Technique

The antiseptic solution must remain on the insertion site and be allowed to air dry completely before catheter insertion or dressing application. 1, 2

• Apply two consecutive 30-second applications separated by sufficient time to allow for complete dryness. 3
• For catheter hub and connector disinfection, use 2% chlorhexidine in 70% isopropyl alcohol before each access. 1, 2
• Keep chlorhexidine well away from drugs and equipment to prevent contamination of items that will contact the cerebrospinal fluid. 1

Age-Based Contraindications

Infants Under 2 Months

Chlorhexidine use in infants younger than 2 months cannot be recommended due to potential side effects including systemic absorption and skin irritation. 1, 4

• Chlorhexidine was detected in the blood of 5 out of 10 treated infants after first application in one study, with 7 of 10 showing detectable levels at some point during treatment. 1
• Skin erythema and dryness occur most frequently when chlorhexidine is used with adhesive dressings, particularly in preterm infants with birth weight less than 1000g (11% incidence). 1
• Alcohol-based chlorhexidine preparations have caused chemical burns in extremely premature infants (24-26 weeks gestational age). 4
• If chlorhexidine must be used in this age group, use the minimum volume necessary while ensuring antisepsis. 1

Children Under 6 Years (Oral Use)

Chlorhexidine mouthwash is not recommended for children younger than 6 years due to high risk of swallowing and lack of safety data. 5

• Children aged 3-5 years swallow significant volumes of mouthrinse, leading to potential systemic absorption. 5
• A 3-year-old child cannot reliably expectorate (spit out) the rinse. 5
• There are no clinical trials or safety data supporting oral use in children under 2 years of age. 5

Specific Clinical Applications

Central Venous Catheter Care

• Use 2% chlorhexidine in 70% isopropyl alcohol for skin preparation before insertion. 1, 2
• Disinfect catheter hubs, connectors, and injection ports with 2% chlorhexidine in 70% isopropyl alcohol before each access. 1, 2
• Replace gauze dressings every 2 days and transparent dressings every 7 days. 1
• Consider chlorhexidine-impregnated dressings for patients older than 2 months with short-term catheters at high risk for infection. 1, 2

Central Neuraxial Blockade

Use 0.5% chlorhexidine in 70% alcohol for skin antisepsis before central neuraxial blockade to minimize neurotoxicity risk while maintaining antimicrobial efficacy. 1

• The neurotoxic concentration of aqueous chlorhexidine when injected into CSF appears to be in the region of 0.05%. 1
• Chlorhexidine is neurotoxic at concentrations as low as 0.01% when applied directly to neurons. 1
• Check gloves for chlorhexidine contamination before handling spinal needles or syringes; change gloves if any doubt exists. 1

Blood Culture Site Preparation

• Chlorhexidine reduces blood culture contamination rates by 56.5% (95% CI 19%-77%) compared to other antiseptics. 1
• Both pediatric and adult populations benefit equally from chlorhexidine use for this indication. 1

Side Effects and Adverse Reactions

Common Adverse Effects

• Contact dermatitis occurs in approximately 2.5-5.4% of atopic patients. 6
• Skin erythema and dryness, particularly when used with adhesive dressings. 1
• Tooth staining and altered taste with oral formulations. 6

Serious Adverse Reactions

Hypersensitivity reactions including contact dermatitis, urticaria, and anaphylaxis can occur at any age, with most severe reactions involving application to mucous membranes. 4, 6

• Acute hypersensitivity reactions are often not recognized and may be underreported. 6
• Permanent neurological injury including chronic adhesive arachnoiditis and paraplegia has occurred when chlorhexidine was inadvertently injected into the epidural or spinal space. 1

Critical Pitfalls to Avoid

• Never use chlorhexidine near the neuraxis without allowing complete drying and ensuring no contamination of spinal needles or syringes. 1
• Never apply repeated applications of chlorhexidine; a single application is sufficient and reduces complication risk. 4
• Never use alcohol-based preparations in extremely premature infants (less than 26 weeks gestation) due to burn risk. 4
• Never apply topical antimicrobial ointments routinely at catheter insertion sites as this may promote fungal infection and antimicrobial resistance. 1
• Never assume chlorhexidine is absolutely contraindicated in all neonates; it has been used safely in large trials and is commonly employed in NICUs for infants over 2 months. 4