Explanation of Issues Encountered in Eye Cream Formulation

It's great that you've started formulating! Let's break down the issues you observed with your eye cream containing REGU®-AGE, Aloe Vera, and Phenoxyethanol.

Phenoxyethanol Dissolution, Residue, and Cloudiness

Phenoxyethanol is a common preservative that is soluble in water. However, when mixing it into a solution that already contains other ingredients like proteins (from REGU®-AGE) and polysaccharides or electrolytes (from Aloe Vera Extract), the overall solubility characteristics of the mixture can change.

• Solubility Limit: It's possible that the concentration of phenoxyethanol exceeded its solubility limit in your specific mixture, causing it to separate initially like oil droplets. Aloe Vera Extract itself often contains phenoxyethanol as a preservative (around 0.5%), so adding more on top of that could contribute to this.
• Ingredient Interactions: The proteins and other compounds in REGU®-AGE and Aloe Vera might interact with phenoxyethanol, affecting its ability to stay fully dissolved or causing a temporary precipitation, which could appear as white residue or cloudiness.
• Mixing Time: As you noted, it required significant stirring to dissolve. Some ingredients, even if soluble, take time and thorough mixing to fully incorporate into a complex solution.

Warming Sensation Under the Eyes

The warming sensation you felt under your eyes is likely a sign of mild irritation. The skin around the eyes is much thinner and more sensitive than the skin on your forearm, which is why you felt it there but not elsewhere.

• Phenoxyethanol Irritation: While Phenoxyethanol is widely used and considered safe at recommended levels, it is known to have the potential to cause irritation, especially in sensitive areas or at higher concentrations.
• Concentration for Eye Products: For eye area products, the recommended maximum usage rate for Phenoxyethanol is typically lower (often no more than 0.5%) to minimize the risk of irritation. If the total concentration in your formula (including any phenoxyethanol already in the Aloe Vera Extract) exceeded this, it could explain the reaction.

Suitability of Phenoxyethanol for Eye Cream

Yes, Phenoxyethanol can be used as a preservative in eye creams, but it is crucial to adhere to the recommended maximum usage rate for the eye area (typically 0.5%) due to its potential for irritation. Your concerns and the information shared in the forum replies about its irritation potential are valid points to consider when formulating for this delicate area.

Using the Cream on Your Neck

Since the skin on your neck is less sensitive than the skin under your eyes, you might be able to use the cream there. However, it's best to perform a patch test on a small area of your neck first to see if you experience any reaction. If the irritation under your eyes was significant, or if you have concerns about sensitivity, it might be safer to avoid using the product altogether.

In summary, the dissolution issues were likely related to the specific mixture composition and solubility limits, potentially exacerbated by the presence of phenoxyethanol in the Aloe Vera Extract. The warming sensation is a common sign of irritation from phenoxyethanol, especially when used around the sensitive eye area, possibly due to the concentration used. While phenoxyethanol is permissible in eye creams, careful consideration of its concentration is necessary.