Medik8 C-Tetra Dupes & Cheaper Alternatives
From 6 Reddit threads · Updated November 3, 2026
7% tetrahexyldecyl ascorbate vitamin C serum; severe acne breakouts reported. The catch: severe acne breakout reported after trying it. Here's what Redditors reach for instead.
The short answer
Best Overall Alternative20% THD ascorbate derivative
Best Cheaper Alternative0.5% retinol starter strength · $9.30 · 29.6 ml vs $53.00 for the original
#1
Best Overall Alternative
The why
An oil-based 20% tetrahexyldecyl ascorbate serum for shoppers building a vitamin C routine, with jojoba oil, squalane, and lightweight emollients. Reddit discussion mostly identifies it in routines rather than documenting visible brightening, so expectations should stay measured.
The original, at a glance
- Why people love it
- Oil-soluble 7% vitamin C derivative
- Price
- $53.00 · 29.6 ml · $1.79/ml
#2
Best Cheaper Alternative
- Size: 29.6 ml
- Price per ml: $0.31/ml (original $1.79/ml)
The why
A 0.5% retinol oil with squalane and jojoba oil targets texture and acne. Redditors report clearer pores, and research found retinol reduced pimples and sore spots; irritation and breakouts make it a poor match for sensitive skin.
One minus
Retinol burn and worsening redness hit sensitive skin
Good forDry Skin
Other alternatives worth a look
Ascorbic acid visibly fades post-acne marks with consistent use · 141 recs
Combination SkinDry Skin
15% pure L-ascorbic acid; strongest vitamin C form · 53 recs
Under MakeupBrightening
20% L-ascorbic acid with Ferulic Acid and Alpha Tocopherol · 188 recs
Oily SkinDewy Finish
15% L-ascorbic acid with tocopherol and ferulic acid · 67 recs
Dry SkinDewy Finish
Beginner-level 0.2% retinol for easing into retinoids · 26 recs
Combination SkinAcne
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