Is this ok to use if you’re a teenager?

Yeah, definitely, good formula for anyone 12+ although if your kid (or you if you're the teen) has combo or oily skin or is acne prone this probably won't be the greatest for them and you'd want something with a light glycolic or azaelic and salicylic acid formula. This formula is much better for dry/normal and/or sensitive skin. Most of this brand's products are also all safe for 12+ though. Just the stronger actives and retinoids could cause skin barrier damage in younger skin although their formulas are generally gentler than many brands.