Feedback on Serum Formula for Oily, Acne-Prone, Dehydrated Skin

Subject: Feedback on your proposed serum formula

Thank you for sharing your proposed serum formula targeting oily, dehydrated skin with dry cheeks, uneven tone, acne, and large pores. It's a comprehensive approach to address multiple concerns.

Based on the ingredients and previous feedback, here are some points to consider regarding adjustments:

Things to Add/Adjust:

• Solubilizer for Tea Tree Oil: The most important adjustment is to add a solubilizer for the Tea Tree Oil (2%). Tea Tree Oil is an oil and will not properly mix into your water-based gel formula without one. Without a solubilizer, the formula will separate. You will need to add an appropriate solubilizer at the recommended usage rate for Tea Tree Oil. This will take up some percentage of your formula, so you'll need to reduce the water percentage accordingly.
• Consider Witch Hazel Concentration: While Witch Hazel is good for pores and oiliness, a 50% concentration might be too drying for the dehydrated areas of your skin, especially the dry cheeks. You might consider reducing the Witch Hazel concentration slightly and potentially adding a dedicated hydrating ingredient like Hyaluronic Acid or Glycerin (if not already accounted for in extracts) to better balance the hydration for the dry areas.
• Licorice Extract Concentration: 0.5% Licorice Extract might be on the lower side for significant effects, depending on the extract's potency. You could consider increasing this slightly if you want more pronounced soothing or brightening benefits, but be mindful of the total active load.

Things to Cut:

• Based on the ingredients listed, nothing necessarily needs to be cut entirely, but rather concentrations might need adjustment (like Witch Hazel) and a solubilizer must be added for the Tea Tree Oil.

Regarding pH Adjustment:

• Yes, you absolutely need to adjust the pH of this formula.
• Azelaic Acid is included at 10%, and its efficacy and stability are pH-dependent. It is generally most effective at a pH between 4 and 5, but this can cause stinging.
• The final pH of your complex mixture will be influenced by Azelaic Acid, Witch Hazel, and other ingredients.
• You will need to measure the pH of the final formula and adjust it using an acid (like Lactic Acid or Citric Acid solution) or a base (like Sodium Hydroxide solution) to a range that is effective, stable, and comfortable for the skin (typically between pH 4.5 and 6.5 for a serum, but specifically considering Azelaic Acid's requirements and skin tolerance).

Summary:

The formula has good ingredients for targeting multiple concerns. The critical step is adding a solubilizer for the Tea Tree Oil. Also, carefully consider the Witch Hazel concentration in light of your dehydrated/dry areas and ensure the final pH is measured and adjusted appropriately for ingredient efficacy and skin comfort. Combining many actives can increase the risk of irritation, so patch testing is highly recommended.