Formulation for Sensitive Skin

Regarding the serum formulation you made for your friend with very sensitive skin, and the reaction she experienced (small bumps), the most likely cause of the irritation is the Silky Serum Base. This base typically contains silicones like cyclomethicone and dimethicone, which can cause reactions in some individuals with highly sensitive skin.

As the staff mentioned, the other active ingredients you included – Repair Activator, Betaine, Bisabolol, Trehalose, Double Hya, B3 (Niacinamide), and Glucosamine – are generally well-tolerated and are even known for their soothing and skin-repairing properties. It is less likely that these ingredients caused the reaction.

To confirm the cause, you could follow the staff's suggestion to test the base ingredient (Silky Serum Base) on your friend's skin by itself. You could also test the preservative separately, as preservatives can sometimes cause sensitivity, although silicone is considered a more common culprit in this type of reaction.

If the Silky Serum Base is indeed the issue, you could consider using a different base that is silicone-free, such as a gel base made with Pro Polymer or a cream base made with Light Cream Maker, as suggested by the staff.