As an emollient, it helps soften skin and supports barrier-replenishing ingredients.

In cosmetics, Glyceryl Stearate is often made from vegetable oils or synthetically produced.

This ingredient may not be fungal-acne safe

Fun fact: The human body also creates Glyceryl Stearate naturally.

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.

Tea tree may cause sensitivity and irritation for some people. This oil naturally contains fragrance such as linalool and limonene.

However, research shows irritation usually occurs when using pure tea tree oil and not in cosmetic products.

Tea tree oil was found to help relieve the symptoms of psoriasis in one study.

Tea tree oil is toxic when ingested. Another study showed it to caused damage to the nervous system of dogs and cats when applied to their skin or given orally.

This ingredient is water-soluble.

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:

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

Creating trihydroxystearin involves using a chemical reaction between hydrogen and castor oil.

This ingredient may not be Malassezia folliculitis safe.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Stay hydrated!