FDA Registration for Stabilized Vitamin C (Natural-C Glycol™) Serum

Regarding the registration of Stabilized Vitamin C (Natural-C Glycol™) Serum with the FDA (อย.), you are correct that this product is designed to be suitable for direct registration and sale as a finished product. The product description confirms this.

However, the product's original pH is in the range of 2-3. According to FDA regulations for cosmetic products applied to the skin, the pH must be at least 3.5. Therefore, yes, you must adjust the pH of the Stabilized Vitamin C (Natural-C Glycol™) Serum to be at least 3.5 for FDA registration and compliance.

Your experience with using Triethanolamine to adjust the pH and feeling warmth or stinging suggests a potential sensitivity to this ingredient. As the staff recommended, Sodium Bicarbonate is an alternative alkaline ingredient you could use to raise the pH.

When adjusting the pH, it is crucial to raise it only enough to meet the minimum FDA requirement of 3.5. Raising the pH significantly higher than this can negatively impact the stability of the Vitamin C (L-Ascorbic Acid) in the serum, leading to faster degradation. Aim for a pH around 3.5 to balance regulatory compliance with product stability.

Remember that adding ingredients other than fragrance (up to 1%) and color is generally not recommended for this serum base as it may affect its stability. If you plan to add anything else, it is best to consult with the R&D team first.