Chlorhexidine for MRSA

Chlorhexidine (usually chlorhexidine gluconate, or CHG) is a broad-spectrum antiseptic, not an antibiotic. It punches holes in the outer membrane of bacteria, spills their cell contents and stops them replicating. Unlike alcohol, it also binds to the outer layer of skin, so a single wash keeps killing microbes for several hours.

It is active against most Gram-positive bacteria (including MRSA and MSSA), many Gram-negatives, several yeasts and enveloped viruses. It is not reliable against bacterial spores or non-enveloped viruses.

• 2% chlorhexidine wipes / cloths — no-rinse daily bathing in ICUs and for high-risk inpatients.
• 4% chlorhexidine body wash / surgical scrub — the usual concentration for pre-operative showers and home decolonisation of recurrent MRSA.
• 2% chlorhexidine in 70% alcohol — the standard skin prep before surgery, central line insertion and blood cultures.
• 0.2% mouthwash — for gum disease and ventilator-associated pneumonia prevention; not used for MRSA nasal carriage.

For recurrent skin infections or before surgery in known MRSA carriers, chlorhexidine body wash is paired with 5 days of mupirocin (Bactroban) nasal ointment. A typical protocol looks like this:

1. Wet the whole body in the shower, then turn the water off.
2. Apply a palmful of 4% chlorhexidine wash from the neck down.
3. Leave it on the skin for at least 1 minute — avoid eyes, ears, mouth and genitals.
4. Rinse off and pat dry with a clean towel.
5. Repeat daily for 5 days. Change towels and bedding on day 1 and day 5.

The full household bundle — laundry, personal items, family members — is on the recurrence and decolonisation page.

Hospitals use chlorhexidine in three main ways to cut MRSA infection:

• Universal ICU bathing with 2% chlorhexidine wipes, shown in the REDUCE MRSA trial to reduce bloodstream infections by about 44%.
• Pre-operative showers with 4% chlorhexidine the night before and morning of surgery, especially for orthopaedic and cardiac procedures.
• Skin antisepsis at the moment of the procedure with 2% chlorhexidine in 70% alcohol before incisions and central lines.

See the hospitals and surgery page for the full evidence-based bundle.

Chlorhexidine is generally very safe when used on intact skin, but worth respecting:

• Dry or irritated skin is common with daily use — moisturise between showers.
• Contact dermatitis in a small minority of users.
• Rare but serious anaphylaxis — the FDA has issued a safety communication. Stop use and seek urgent care if you develop hives, swelling, wheeze or faintness after use.
• Keep out of eyes, ears (can damage the eardrum), mouth and mucous membranes.
• The mouthwash can stain teeth brown and alter taste with prolonged use.

Some staphylococci carry qacA/B or smr efflux-pump genes that raise their minimum inhibitory concentration to chlorhexidine. The concentrations used on skin (2–4%) are still many-fold above those levels, and clinical decolonisation continues to work. Using chlorhexidine only for defined indications — not as everyday soap — keeps that margin comfortable.