Paula's Choice C15 Super Booster - 20 ml

It is generally recommended to use Vitamin C in the morning and retinol in the evening to minimize potential irritation and maximize product efficacy.

With daily use of 2-3 drops, the 20 ml bottle is formulated to last approximately 2 to 3 months.

It is suitable, but due to the 15% concentration, patch testing is recommended. Introduce it slowly to see how your skin reacts.

Refrigeration is not required, but storing it in a cool, dark place like a drawer or cupboard is essential for maintaining stability.

Yes, you can mix it with most serums or moisturizers, but avoid mixing it with products containing exfoliating acids (AHA/BHA) to prevent irritation.

This is common with high-strength Vitamin C. If it persists or turns into burning, rinse off immediately and reduce usage frequency to every few days.

This indicates oxidation. While it may still be safe, the efficacy is reduced. Ensure the cap is tightened firmly after every use and store in a dark area.