Niacinamide vs vitamin C: which goes first in your routine

The internet got this wrong for about a decade. The old advice - "never layer niacinamide with vitamin C, they cancel each other out" - comes from a 1960s study run at pH and temperature conditions nothing like your bathroom counter. Modern formulations don''t have the issue.

The actual rule

Both can go in the same routine. The order that gives you the best penetration: vitamin C first (it needs an acidic pH to work, around 3.5), then niacinamide (works at a wider pH range, 5-7). Apply the C, wait 60 seconds, apply the niacinamide.

What each one is actually doing

Vitamin C (L-ascorbic acid, 10-20%): neutralizes free radicals from UV exposure, brightens existing hyperpigmentation, and supports collagen synthesis. Works in the morning under sunscreen.

Niacinamide (vitamin B3, 4-10%): regulates sebum, strengthens the skin barrier, evens tone, reduces redness. Works morning or night, plays well with retinoids and acids.

The one combination to actually avoid: vitamin C with copper peptides at the same time. Different mechanism, same antagonism - and that one is real. Stagger them by 12 hours.