I'm 15, should I use vitamin C?

There is no age limit for vitamin C (To my knowledge) but it depends on your concerns. As far as for your age, the cell turnover is quite fast so you actually don't need any active ingredient but if you wanna start, start with low percentage like 5% and see how it works. Vitamin C is mostly used for brightening and fading of acne scars so make sure to check if the ingredient meets your concern.

What problems are you looking to solve with a Vit C serum?

wow good

there is no age limit for vic c so just use it

If u need, just use it. No age limit