Clearing with procedures and preventing with medication is the standard pairing.
Ingredients that suppress pigment formation are used as oral or topical medication. Procedures clear pigment already there while medication prevents new pigment, so the two are often used together. It has to be used consistently to hold, and only means something alongside sun protection.
Pigmentation medication uses oral or topical agents that suppress pigment formation. Treatments break down pigment that already exists while medication stops new pigment forming, so their roles differ and they are often used together. Medication alone will not clear existing pigment quickly.