C-Tetra — Reddit Reviews
by Medik8
Updated November 3, 2026
7% tetrahexyldecyl ascorbate vitamin C serum; severe acne breakouts reported.
What the community says
A 7% tetrahexyldecyl ascorbate serum built around an oil-soluble vitamin C derivative. It fits users seeking this format, but jojoba oil, grapefruit peel oil, and listed fragrance allergens make breakout-prone skin a genuine gamble.
What this means for you
Backed by 4 threads from r/30PlusSkinCare, r/40plusskincare and 1 more.
Read the threads ↓What people love
- Oil-soluble 7% vitamin C derivative
- Frequently named in mature-skin vitamin C routines
Watch out for
- Severe acne breakout reported after trying it
- £60 price invites comparison with cheaper alternatives
Product details
Product Traits
Key Ingredients
Skin type data limited
Where to buy
What the science says
Hyperpigmentation
Some evidence
Vitamin C: 9 studies tested it directly. See all 19 studies
What the studies found
- Most studies found vitamin C helped fade dark patches, especially melasma
- It often worked better than a placebo when put on the skin for melasma
- Used with microneedling or peels, it often improved dark patches more
- Some studies found it worked about as well as other dark-spot treatments, not better
- The side effects were usually mild and brief
Studied at 3–30%this product: 7%
Anti-Aging
Some evidence
Vitamin C: 4 studies tested it directly. See all 12 studies
What the studies found
- All 4 studies that tested it directly found it helped with signs of aging
- It improved the look and texture of sun-damaged skin more than a placebo
- It helped smooth wrinkles, roughness, crow’s-feet, and uneven skin tone
- It did not clearly beat a placebo for how much water the skin held
- No irritation or sensitivity was reported in one study
Studied at 5–10%this product: 7%
Research context, not treatment advice. Studies are about the ingredient, not necessarily this exact product.
Real Reddit threads — 6 mentions across 4 threads
Medik8 C-Tetra on Reddit, in one place — 4 threads from r/30PlusSkinCare, r/40plusskincare and 1 more, summarized.
“I tried the medik8 tetra c just because everyone was raving about it, it was £60 and gave me a severe acne break out.”
Cautionary
“Don't fall for the skin care hype... everyones skin is different.”
Cautionary
“What works for one person could be awful for another.”
Cautionary
“And Medik8 C-Tetra”
Mentioned
“Revision Skincare C+ Correcting Complex, Medik8 C Tetra, Skinfix”
Mentioned
“serum - medik8 c-tetra”
Positive
“That toner is fine to use after actives like vitamin c.”
Positive
“The whole thin-to-thick rule is really only for non-active serums.”
Positive
