Medik8 C-Tetra® Luxe Lipid Vitamin C Enhanced Radiance Serum

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:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

Tocopheryl Acetate is commonly found in both skincare and dietary supplements.

These fatty acids help the skin create ceramides. Ceramides play a role in repairing the skin barrier.

Helianthus Annuus Seed Oil helps moisturize the skin. This in turn helps the skin look more rejuvenated and smoother.

Sunflowers are rich in vitamin E.

Historians believe Indigenous cultures of North America domesticated sunflowers before corn. Thus they relied on sunflower oil for a variety of uses. One such use is moisturizing skin and hair.

Sunflower seed oil may not be fungal acne safe. We recommend speaking with a professional if you have any concerns.

Olive oil also contains antioxidants such as Vitamin E. Antioxidants may help reduce signs of aging by fighting unstable free-radical molecules. It also contains Vitamins A (retinol), D, and K.

The squalene in olive oil makes it a great emollient. Emollients help soothe and soften your skin by trapping moisture in. This makes olive oil a great skin moisturizer.

Studies show olive oil to have antibacterial and antifungal properties in low concentrations. Another study found olive oil irritated sensitive oily skin. We always recommend speaking with a professional about using this ingredient in your routine.

Due to the fatty acid content, this ingredient may not be fungal-acne safe.

The content of sweet almond oil makes it a great emollient; it can help soften and hydrate your skin. Emollients create a barrier over your skin to trap moisture in. Sweet almond oil has antioxidant properties.

Those with an almond allergy should be careful of this ingredient and speak with a professional about using it in your skincare.

This ingredient may not be fungal-acne safe.

This ngredient also has antioxidant properties from Vitamins A, C, and E. Antioxidants help fight free-radicals. Free-radicals are molecules that may damage your skin cells. Besides being antioxidants, these vitamins provide plenty of skin benefits as well.

Limonene acts as an antioxidant, meaning it helps neutralize free radicals.

When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.

The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.

The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.

The term 'citral' is a collective term for two geometric isomers: geranial/Citral A and neral/Citral B.

This ingredient has a scent that is floral, spicy tropical, and citrus-like.

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)-