The color change in Apollo Expert Niacinamide 12% With Vitamin C 2% Face Serum from colorless to brown is likely due to the natural oxidation of Vitamin C, which is common in such formulations and does not necessarily mean the product is unsafe.

🩺 Impact on Sensitive Skin

This color change usually does not increase the risk of irritation for sensitive skin if the product is stored properly—away from direct sunlight, heat, and humidity as recommended. However, since you have sensitive skin, it’s important to watch for any unusual redness or discomfort after use.

🩺 How to Verify Product Authenticity

To ensure you buy a genuine serum online:

• Purchase only from official or reputable sellers.
• Check for proper packaging, batch numbers, and expiry dates (the product you mentioned expires Dec-26).
• Avoid deals that seem too cheap or sellers without verified reviews.

🏥 Recommendations for Sensitive Skin

• Perform a patch test on a small skin area before full use.
• Start with a small amount and observe for 24-48 hours for any adverse reaction.
• Discontinue use and consult a dermatologist if irritation occurs.

If you want, I can explain more about how Vitamin C oxidation affects skincare products. Meanwhile, consulting a dermatologist before switching products is advisable for your sensitive skin.