Two weeks in, you are standing at the mirror deciding it has not worked.

Two weeks is not a verdict. For most of what you have bought, it is barely the beginning.

Why skin is slow

A skin cell takes roughly a month to travel from the bottom of the epidermis to the surface and shed. That cycle stretches as you get older.

Anything working on tone or texture has to wait for that turnover to bring the change up to where you can see it. Nothing you apply on Monday is visible on Friday.

What to expect, and when

  • Hydration — hours to days. Humectants and a decent moisturiser show almost immediately. If your skin feels less tight by the end of week one, that is the product working exactly as it should.
  • Barrier repair — one to four weeks. Mild irritation settles in a week or two. Skin that has been over-exfoliated for months takes closer to six.
  • Niacinamide — four to eight weeks. Redness and general evenness first. Tone and oil later.
  • Vitamin C — eight to twelve weeks. Brightness before pigment. The dullness lifts well before the spots do.
  • Alpha-arbutin and other brighteners — twelve weeks, minimum. Often longer for marks that have been there a year.
  • Retinoids — twelve weeks, and worse before better. Weeks two to six are frequently the roughest. That is the well-documented part, not a sign of failure.
  • Sunscreen — never visible. Its whole job is the mark you do not get. You will never see the evidence, which is precisely why it is the step people drop.

How to actually judge it

The mirror is a bad instrument. You look at your face every day, so gradual change is the one kind of change you are least able to see.

Photograph instead. Same window, same time of day, no makeup, no filter, face straight on and then turned. One photo every four weeks.

Compare week one to week twelve, never week one to week two. Twelve weeks apart, a difference either exists or it does not, and you will stop arguing with yourself about it.

When to stop

Not at week three because you are impatient. But do stop if:

  • Stinging or burning has not settled after two weeks of use.
  • You are getting new breakouts in places you never break out, eight weeks in.
  • Your skin is flaking, tight and reactive to things that never bothered it before.

That last one is usually a barrier problem rather than an allergy, and the fix is subtraction rather than another product.

The honest summary

Give a routine three months before you decide. Give a brightening routine six.

Anything sold on a fortnight is selling you the sentence, not the result.