pH of Eye Cream Formulation: Stability, Efficacy, and Irritation

Question

Regarding my eye cream formulation:1. Is the amount of water too low?2. I measured the pH and it is only 4.25. Will this cause any ingredients to degrade? Will it still be effective for wrinkle reduction?3. If I use Triethanolamine to adjust the pH (alkaline adjuster), will it cause irritation or itching around the eyes? If you had to decide between leaving the pH at 4.25 without adding alkali, and adding alkali to adjust the pH, which would be gentler?

MySkinRecipes Expert · Accepted Answer

Subject: pH value of eye area products

Regarding your questions about the eye cream formulation:

Water amount: The staff confirmed that the amount of water is sufficient as other ingredients are water-soluble, and the formula should not separate.
pH 4.25 stability and efficacy: The staff believes that a pH of 4.25 is not a significant concern and the ingredients should still be effective at this level. However, if you are concerned or producing commercially, they recommend adjusting the pH slightly higher, closer to 5.
Acidity and eye irritation: While pH 4.25 might be acceptable, the staff's recommendation to adjust the pH higher (closer to 5) suggests that a slightly less acidic environment is generally preferred for the sensitive eye area to minimize potential irritation.
Target pH for future formulations: Based on the staff's suggestion, a target pH closer to 5 is recommended for eye cream formulations.
Triethanolamine for pH adjustment and gentleness: The staff strongly advises against using Triethanolamine or other bases to adjust the pH in this type of formula. They state that these bases can cause skin irritation. Instead, they recommend adjusting the pH by increasing the proportion of ingredients with a neutral or slightly alkaline pH, such as Niacinamide (Safe-B3) or Panthenol (Vitamin B5). Adjusting the pH using these active ingredients is considered much gentler than using a base like Triethanolamine. Therefore, adjusting the pH to near 5 using suitable active ingredients is considered more gentle than leaving it at 4.25 or adjusting with a base.