What's the yellow stuff they put on before surgery? A closer look at antiseptics

September 23, 2025 •

3 min read

According to the World Health Organization, surgical site infections are a significant global health concern, affecting millions of patients annually. A critical step in preventing these infections is the application of antiseptics, like the yellow stuff they put on before surgery, to disinfect the skin at the incision site.

Quick Summary

The yellow or orange-tinted liquid applied before surgery is a powerful antiseptic designed to kill surface bacteria and prevent infection. It is most commonly povidone-iodine (often sold under the brand name Betadine) or a colored formulation of chlorhexidine gluconate, both crucial for ensuring a safe surgical procedure by drastically reducing the risk of surgical site infection.

Key Points

Povidone-Iodine (Betadine): This yellow-brown antiseptic releases iodine to kill microorganisms by oxidizing them. It is a common choice for surgical skin preparation due to its broad-spectrum activity.
Chlorhexidine Gluconate (CHG): Often tinted orange or green, this antiseptic works by disrupting bacterial cell membranes. It offers longer-lasting antibacterial effects on the skin than povidone-iodine.
Colored Tints: The color is a critical visual aid for the surgical team, confirming that the entire surgical site has been properly and thoroughly disinfected.
Reduces Surgical Site Infection (SSI): The primary purpose of this antiseptic process is to kill or reduce the number of bacteria on the skin, significantly lowering the risk of infection after surgery.
Multi-step Protocol: The process involves several steps, including preoperative washing at home and final antiseptic application in the operating room, for maximum effectiveness.
Not Just a Disinfectant: In addition to killing bacteria, the antiseptic creates a protective barrier on the skin that lasts throughout the surgical procedure.

Understanding the surgical 'paint'

The brightly colored liquid applied before surgery serves a critical purpose in preventing infection. This 'surgical paint' is typically one of two main types of antiseptic: povidone-iodine or chlorhexidine gluconate. Both are powerful agents designed to eliminate microorganisms from the skin's surface.

Povidone-Iodine: The classic choice

Povidone-iodine (PVP-I), widely recognized by the brand name Betadine, has a long history of use in surgical settings. It works by releasing iodine, which acts as an oxidizing agent, damaging microbial cells.

Broad-spectrum efficacy: It is effective against a wide range of pathogens.
Sustained release: Provides a longer-lasting effect.
Visual confirmation: Its natural yellow-brown color helps ensure complete coverage of the surgical area.
Mucous membrane use: Certain formulations are safe for use on mucous membranes.

Chlorhexidine Gluconate: A newer alternative

Chlorhexidine gluconate (CHG) is another common antiseptic, often used with added dyes like orange or green to make it visible on the skin. CHG kills microorganisms by disrupting their cell membranes.

Why it might be used instead of povidone-iodine

Hospitals increasingly favor CHG due to several advantages:

More persistent activity: It remains active on the skin for up to 7 days.
Rapid action: CHG provides a quick reduction in bacterial count.
Effectiveness in organic matter: Its efficacy is less affected by the presence of blood compared to povidone-iodine.
Tinted options: Available in various colors to ensure visibility on different skin tones.

The process of preoperative skin preparation

Preoperative skin preparation is a standardized process aimed at minimizing the risk of surgical site infection (SSI). This involves several steps:

Step 1: Preoperative washing

Patients may be asked to wash with an antiseptic soap, such as CHG, before surgery to reduce the overall bacterial load on their skin.

Step 2: Hair removal

Shaving is generally avoided due to the risk of creating micro-abrasions. If hair removal is necessary, sterile clippers are preferred.

Step 3: Application of the antiseptic

The chosen antiseptic is applied to the surgical site using a sterile applicator, covering the area and allowing it to dry completely. The color confirms proper application.

Comparing povidone-iodine and chlorhexidine gluconate


Feature	Povidone-Iodine (PVP-I)	Chlorhexidine Gluconate (CHG)
Mechanism of Action	Releases free iodine to oxidize microbial cells	Disrupts bacterial cell membranes
Persistence on Skin	Lasts for a few hours	Lasts for at least 7 days
Speed of Action	Good	Very rapid
Effectiveness in Blood	Neutralized by organic matter	Remains active in the presence of blood
Tint	Naturally yellow-brown/reddish	Often tinted orange or green for visibility
Mucous Membrane Use	Can be used on mucous membranes	Should not be used on mucous membranes due to burns

Why is this so important for health?

The application of these antiseptics creates a sterile field, reducing the risk of bacteria entering the surgical wound. This is crucial for preventing surgical site infections, which can lead to serious complications. The color provides a visual check, ensuring the entire area is protected. This practice is a key component of modern infection control, building on the work of pioneers like Joseph Lister.

Conclusion: A simple step with significant impact

The yellow or orange liquid used before surgery is a vital antiseptic, typically povidone-iodine or chlorhexidine, that protects against infection. This colored preparation, part of a careful protocol, is essential for patient safety and contributes significantly to successful surgical outcomes.

External Link

Science Museum's overview of Joseph Lister's antiseptic system

Frequently Asked Questions

No, it is not always the same. The yellow or orange color often comes from povidone-iodine (Betadine), but a different antiseptic called chlorhexidine gluconate may also be used, with an added dye for visibility.

No, the antiseptic liquid applied to the skin before surgery should not be painful. It may feel cool or have a tingling sensation, but it is not the same as stinging alcohol you might use on a cut at home.

The color is added as a visual indicator. It allows the surgical team to easily see which areas of the skin have been prepped, ensuring no spots are missed and the entire surgical field is disinfected effectively.

While uncommon, an allergic reaction is possible. You should inform your healthcare provider if you have any known sensitivities to iodine or chlorhexidine. Symptoms can include skin irritation, redness, or a rash.

Yes, povidone-iodine can stain clothing and fabrics. However, this is typically cleaned off after surgery. The colored dyes in some chlorhexidine solutions can also cause temporary staining.

Some hospitals prefer chlorhexidine because it often has a longer-lasting effect and is less neutralized by the presence of blood and other organic matter. However, both are effective antiseptics.

The primary goal is to significantly reduce the risk of surgical site infection (SSI) by eliminating or reducing the number of bacteria on the skin before the first incision is made.