Eye Stinging Issue in Makeup Remover Formula

The stinging sensation reported by your customers is likely due to a combination of the concentration of the cleansing agent and the choice of preservative/surfactant in your formula.

Analysis of the Formula

1. High Concentration of Cleansing Agent: You are using MakeUp-Wash™ (PEG-6 Caprylic/Capric Glycerides) at 10%. While this is within the general usage range, for products used around the sensitive eye area, a concentration of 3-5% is typically recommended. High levels of surfactants, even gentle ones, can disrupt the tear film and cause stinging.
2. Irritating Cationic Surfactant: Cetrimonium Bromide (Cetrimide C16) is a cationic surfactant. Cationic substances are known to be significantly more irritating to the eyes than the non-ionic surfactants typically used in micellar waters. Even at 0.1%, it may be contributing to the discomfort.
3. Lack of Chelating Agent: Your formula does not include a chelating agent. Adding Disodium EDTA helps to stabilize the formula and increases the efficiency of the preservative system by binding metal ions that germs need to grow.
4. Preservative System Optimization: While Phenoxyethanol (Extra Pure) is a standard preservative, using it alone or with irritating co-preservatives in an eye product can be tricky. Using a preservative booster can allow you to maintain safety while reducing irritation.

Recommended Adjustments

To resolve the stinging issue, consider the following modifications:

• Reduce MakeUp-Wash™: Lower the concentration to 3-5%. This is usually sufficient for effective makeup removal while being much gentler on the eyes.
• Remove Cetrimonium Bromide: Eliminate this ingredient to reduce the potential for eye irritation.
• Add a Chelating Agent: Incorporate Disodium EDTA at 0.2% to improve stability and preservative performance.
• Use Preservative Boosters: Add 1,2-Hexanediol (Super-Purified, Odorless) at 2-3% or Caprylyl Glycol (1,2-Octanediol) at 0.5%. These ingredients act as humectants and "boost" the effectiveness of your primary preservative, allowing for a safer and milder formula.
• Check pH: Ensure the final pH of your makeup remover is between 5.5 and 7.0. The pH of human tears is approximately 7.4, so a formula that is too acidic will cause stinging.

Suggested Revised Formula

• Water: to 100%
• MakeUp-Wash™: 5%
• Glycerin (USP/Food Grade): 5%
• Xylooligosaccharide (XOS, 95%): 1%
• 1,2-Hexanediol (Super-Purified, Odorless): 2%
• Phenoxyethanol (Extra Pure): 0.4%
• Disodium EDTA: 0.2%