No.5 Vitamin Concentrated Serum — Reddit Reviews

• Hyperpigmentation

  Strong evidence

  Tranexamic Acid: 16 studies tested it on its own. See all 21 studies→

  On Reddit: Acne marks slowly fade for some users, who also report reduced pigmentation and a subtle glow. 40 mentions

  Both ingredients for hyperpigmentation

  Tranexamic Acid · Strong evidence

  • Most studies found it helped fade dark patches, especially in melasma
  • It often worked about as well as hydroquinone or vitamin C
  • It could work better when used with microneedling or laser than those treatments alone
  • Different forms helped, including pills, skin treatments, and injections
  • The most common side effects were stomach upset, skin irritation, and menstrual changes

  Niacinamide · Some evidence

  5 studies tested it on its own. See all 20 studies→

  • All 5 studies that tested it on its own found it helped fade dark spots
  • On its own, it reduced facial darkening and made skin look lighter than a placebo
  • It also improved dark spots linked with sun damage in one clinical trial
  • Used with other ingredients, it faded patches more than niacinamide alone or the other ingredient alone
  • The side effects were similar and mild in the study that reported them

• Acne

  Some evidence

  Niacinamide: 6 studies tested it on its own. See all 17 studies→

  On Reddit: Lingering marks from breakouts fade slowly, and one user reports improved acne-related hyperpigmentation. 4 mentions

  What the studies found

  • Most studies found niacinamide helped acne
  • It often cleared acne about as well as clindamycin when put on the skin
  • Some studies found it helped reduce red, sore spots and pimples
  • Some evidence is still uncertain because some studies found no clear difference

• Anti-Aging

  Some evidence

  Niacinamide: 3 studies tested it on its own. See all 9 studies→

  What the studies found

  • All 3 studies that tested it on its own found it helped with signs of aging
  • Studies found it improved the look of wrinkles and made skin seem firmer
  • Studies also found it helped dark spots and reduced redness and yellowing
  • One study found it helped skin hold more water and lowered water loss through the skin
  • Used with another ingredient, it improved dark spots, fine lines, wrinkles, and firmness more than niacinamide alone

• Dehydration

  Not proven yet

  Few or mixed studies. This claim isn't established.

  Panthenol: 2 studies tested it on its own. See all 3 studies→

  What the studies found

  • The results are split, so there is no clear answer yet for dehydration
  • Some studies found panthenol helped skin hold more water
  • Some studies found panthenol lowered water loss through the skin
  • One study found it also helped the skin barrier recover better after washing

• Skin Barrier

  Not proven yet

  Few or mixed studies. This claim isn't established.

  Niacinamide: 1 study tested it on its own. See all 17 studies→

  Both ingredients for skin barrier

  Niacinamide · Not proven yet

  • The one study that tested it on its own found it helped the skin barrier
  • It lowered water loss through the skin
  • It increased the thickness of the outer skin layer

  Panthenol · Not proven yet

  Few or mixed studies. This claim isn't established.

  1 study tested it on its own. See all 10 studies→

  • The one study that tested it on its own found it helped
  • Skin treated with panthenol lost less water through the skin
  • Higher strengths like 1.0% and 5.0% seemed to help the most

Research context, not treatment advice. Studies are about the ingredient, not necessarily this exact product.