Medik8 C-Tetra Lipid Vitamin C Serum Versus Biossance Squalane + Vitamin C Rose Oil

Medik8 C-Tetra Lipid Vitamin C Serum Versus Biossance Squalane + Vitamin C Rose Oil

This brightening serum is formulated around Tetrahexyldecyl Ascorbate and Simmondsia Chinensis Seed Oil to brighten dull-looking skin and fade the look of dark spots.

This brightening oil is formulated around Squalane and Tetrahexyldecyl Ascorbate to brighten dull-looking skin and hydrate skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Simmondsia Chinensis Seed Oil

Cyclopentasiloxane

Cyclohexasiloxane

Tetrahexyldecyl Ascorbate

Citrus Grandis Peel Oil

Tocopheryl Acetate

PPG-12/Smdi Copolymer

Limonene

Citral

Linalool

Geraniol

Simmondsia Chinensis Seed Oil, Cyclopentasiloxane, Cyclohexasiloxane, Tetrahexyldecyl Ascorbate, Citrus Grandis Peel Oil, Tocopheryl Acetate, PPG-12/Smdi Copolymer, Limonene, Citral, Linalool, Geraniol

Squalane

Caprylic/Capric Triglyceride

Pistacia Lentiscus Gum

Rosa Damascena Flower Extract

Citronellol

Squalane, Tetrahexyldecyl Ascorbate, Caprylic/Capric Triglyceride, Pistacia Lentiscus Gum, Rosa Damascena Flower Extract, Geraniol, Citronellol

Reviews

Alternatives

Ingredients Explained

These ingredients are found in both products.

Ingredients higher up in an ingredient list are typically present in a larger amount.

Geraniol is used to add fragrance/parfum to a product. It is the main component of citronellol. It is a monoterpenoid and an alcohol.

Monoterpenes are naturally found in many parts of different plants.

Geraniol can be found in many essential oils including Rose Oil and Citronella Oil. The scent of Geraniol is often described as "rose-like". Many foods also contain Geraniol for fruit flavoring.

Geraniol can irritate the skin when exposed to air. However, irritation depends on the ability of geraniol to penetrate into the skin. In general, geraniol is not able to penetrate skin easily.

Geraniol is colorless and has low water-solubility. However, it is soluble in common organic solvents.

Like citronellol, it is a natural insect repellent.

2,6-Octadien-1-ol, 3,7-dimethyl-, (2E)-

Tetrahexyldecyl Ascorbate (THD) is a stable and oil-soluble form of Vitamin C.

THD is special in that it has the ability to travel deeper into skin than traditional ascorbic acid while maintaining the same skin benefits (double win!).

Because it’s oil-soluble, THD dives deep into your skin’s fatty layers (think ceramides and cholesterol) to fight off the kind of free radicals that mess with your skin barrier. This makes it a great pair with water-based vitamin C (ascorbic acid) that mainly works on the surface.

Even at just 0.1%, THD is already showing great antioxidant activity. When used up to 2%, it helps keep your skin happy and calm, especially when it’s stressed from pollution or sun.

Want to fade dark spots or tackle hyperpigmentation? You’ll want 5% or more. Pairing it with brightening buddies like niacinamide or licorice root gives even better results. One study even used 30% THD with other brighteners and saw real results on stubborn discoloration, even in melasma-prone skin.

A note on THD: It’s has a slightly silky, oily texture and usually shows up colorless or pale yellow (though the exact shade can vary by supplier).

While you can sneak it into water-based formulas, it really shines when paired with silicones or oils, which help your skin soak it up better.

THD is pretty stable, but it’s still vulnerable to degradation like ascorbic acid. Too much light or heat (above 113°F / 45°C) can break it down over time. Go for dark and opaque packaging that keeps it safe and shady!

Read more about other types of Vitamin C:

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