CHG soap is a medical-grade cleanser containing chlorhexidine gluconate, an antiseptic that kills bacteria, fungi, and certain viruses on the skin. It’s most commonly used before surgery to reduce the risk of infection, but you may also encounter it in hospitals, athletic settings, or as an over-the-counter product for skin cleansing. Unlike regular soap, which washes germs away mechanically, CHG binds to your skin and keeps killing microbes for hours after you rinse it off.
How CHG Kills Bacteria
Chlorhexidine gluconate carries a positive electrical charge, which makes it naturally attracted to bacterial cells (which carry a negative charge). Once it reaches a bacterium, it passes through the cell wall and damages the inner membrane, causing the cell’s contents to leak out. At higher concentrations, it goes further, destroying the bacterium’s DNA and energy molecules from the inside. This two-stage process is what makes CHG effective at both slowing bacterial growth and outright killing bacteria, depending on concentration.
CHG works against a broad range of organisms. It handles both common skin bacteria and more dangerous pathogens like MRSA (methicillin-resistant Staphylococcus aureus). It also has antifungal properties and can inactivate several viruses, including herpes simplex, hepatitis B, and influenza A.
Why It Stays Active After Rinsing
The feature that sets CHG apart from regular antibacterial soap is residual activity. Because the molecule binds to proteins in your skin, it doesn’t just wash down the drain. A single two-minute application of 4% CHG has been shown to protect against MRSA for up to four hours afterward. That persistent barrier is the entire reason hospitals favor it over ordinary soap before procedures. Regular soap removes bacteria in the moment, but new bacteria can begin colonizing the skin almost immediately. CHG keeps working in the background.
Common Concentrations
CHG soap typically comes in two strengths: 2% and 4%. The 4% liquid wash (sold under brand names like Hibiclens) is the traditional standard for pre-surgical skin preparation and is available over the counter at most pharmacies. The 2% version often comes as a pre-moistened cloth rather than a liquid, which makes application more consistent. Both concentrations significantly reduce bacteria on the skin, and research comparing them has found that the 2% cloths can actually outperform the 4% liquid wash in certain body areas, likely because the cloth format ensures more even coverage.
For pre-surgical use, hospitals typically provide whichever format fits their infection-prevention protocol. If you’re buying CHG soap on your own before a scheduled procedure, your surgeon’s office will usually specify which product and concentration to use.
How to Use CHG Soap Correctly
If you’ve been given CHG soap before a surgery, the application process matters more than you might expect. Johns Hopkins Medicine’s pre-operative instructions outline the key steps: turn the water off before applying the soap so it doesn’t rinse away prematurely, then apply it to your entire body from the jawline down. Wash thoroughly for five minutes, giving extra attention to the area where the incision will be made. Turn the water back on and rinse completely.
One important detail: do not follow up with your regular soap or body wash afterward. Regular soap can strip the CHG residue from your skin, defeating the purpose. You want that antiseptic layer to remain intact. Most surgical protocols ask patients to repeat this process the night before and the morning of their procedure.
Where Not to Apply It
CHG is safe for most of your body’s skin, but there are specific areas where it should never be used. The product label for Hibiclens, one of the most widely used CHG products, lists clear restrictions:
- Eyes: CHG can cause serious, permanent eye damage if it gets in and isn’t immediately flushed out.
- Ears: If it enters the middle ear through a perforated eardrum, it can cause deafness.
- Mouth: The wash form is not meant for oral use (though separate CHG mouthwash products exist at much lower concentrations).
- Genital area: The skin and mucous membranes in this region are too sensitive for CHG wash.
- Open wounds or deep tissue: CHG should not contact the meninges (the membranes surrounding the brain and spinal cord) or be used on deep surgical wounds.
Keep the soap from the jawline down and away from sensitive areas, and you’ll avoid these risks entirely.
Side Effects and Skin Reactions
Most people tolerate CHG soap without any problems. The most common side effect is mild skin irritation: redness, dryness, or a slight itching at the application site. This is more likely if you have sensitive skin or use the product frequently over several days.
Allergic reactions are rare but possible. Signs include blistering, peeling, a skin rash, or swelling of the face, hands, or feet. In very rare cases, CHG can trigger a serious allergic reaction with difficulty breathing and facial swelling. If you notice any of these symptoms, stop using the product. Because of the potential for skin irritation and increased absorption, CHG is not recommended for infants under two months old.
Uses Beyond Surgery
While pre-surgical bathing is the most well-known use, CHG soap shows up in several other settings. Hospitals use daily CHG bathing for ICU patients to reduce bloodstream infections from IV lines. The CDC has strongly recommended pre-operative CHG showers since 1999 as part of standard surgical infection prevention, and that recommendation has since expanded into broader hospital care bundles targeting MRSA and other drug-resistant organisms.
Athletes sometimes use CHG soap to prevent skin infections in contact sports, where bacteria like MRSA can spread through shared equipment and skin-to-skin contact. Some people with recurrent skin infections, such as boils or folliculitis, also use it periodically on the recommendation of their dermatologist. It’s not meant as an everyday body wash for healthy skin, though. Regular use when you don’t need it can disrupt normal skin flora and increase the chance of irritation.