Sun spots are the result of years of accumulated UV radiation that activates melanocytes irregularly. They're not superficial — they're in the superficial dermis and the dermo-epidermal junction. That's why they take months to treat with topical actives and weeks to worsen if SPF fails for a single day during treatment.

Why SPF Is the Most Important Step in Treatment

Any depigmenting active works by inhibiting melanin production. UV radiation activates melanocytes. Without SPF, the day's UV activates more melanin than the active inhibited overnight. The result is that treatment doesn't progress — or reverses. SPF isn't a bonus in treatment: it's the condition without which treatment doesn't work.

The 3 Actives With the Most Evidence for Dark Spots

Alpha-Arbutin

Tyrosinase inhibitor (enzyme that produces melanin) more potent than kojic acid and regular arbutin. Without hydroquinone's side effects. Evidence for sun spots and melasma at 2% in 12 weeks.

Stabilised Vitamin C

Dual action: inhibits tyrosinase + neutralises free radicals that activate melanocytes. Documented synergy with alpha-arbutin.

Niacinamide

Inhibits melanosome transfer from melanocytes to keratinocytes — a different, complementary mechanism to the above. At 4–5%, evidence for dark spot reduction in 8 weeks.

The Treatment Protocol

Morning: vitamin C → moisturiser → SPF50
Night: dark spot serum → moisturiser
2–3x/week: lactic acid for surface renewal (accelerates elimination of deposited melanin)

Realistic Timeline

• 4 weeks: first improvements in overall tone
• 8–12 weeks: visible reduction of specific dark spots
• 6 months: complete result for deep spots or melasma