which acid would you recommend?

since tretinoin will make ur skin more sensitive i suggest u try mandelic acid! i heard from a youtube video by dr. vanita rattan that mandelic acid is better for sensitive skin compared to other ahas like glycolic. i also really love this one from the ordinary and i noticed a lot of changes from my hyperpigmentation and irritation :)) i also didnt have any purging/irritation when i first used it but remember to patch test any skincare with actives just in case hihi

I would try tranexemic acid or alpha arbutin, as they both help with hyperpigmentation without damaging the skin barrier. This formula makes dramatic results because it also has those two listed above plus niacinimide, kojic acid, centella, turmeric, licorice and azelaic acid.

Lactic acid is a gentle AHA and at the same time humectant that can draw in hydration to skin!

then .. u can use aha like glycolic acid, lactic acid and mandelic acid . three of them work best for acne n hyperpigmentation while glycolic acid works best for blackheads ^^ . but really discouraged to use those suggestions with tretinoin =/

My favorite is glycolic acid. It works magic on me as milder acids as mandelic or lactic doesn’t work as good