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Specifically, AHAs work by breaking down the structural "glue" holding the old skin cells in place. Getting rid of the old skin cells allows skin to regenerate newer skin cells in its place. A build up of dead skin cells can lead to tired and dull looking skin.

Due to this, glycolic acid helps with:

Fun fact: Glycolic acid increases skin hydration by playing a role in creating molecules that create hyaluronic acid naturally.

When starting glycolic Acid, it is normal to feel slight stinging.

The pH value and concentration of glycolic acid play a role in the effectiveness of the product. Concentrations between 5-20% glycolic acid have been shown to be effective in clinical studies.

Recent studies have shown Glycolic Acid may protect the skin against UV damage. However, you should always wear SPF, especially when using exfoliants.

Read more about some other popular AHA's here:

Not only does it help exfoliate the skin, it helps strengthen the skin's barrier. When applied, lactic acid helps the skin create ceramides.

Lactic acid is an over-the-counter chemical exfoliant that comes from the fermentation of lactose — a carbohydrate found in milk.

Legend has it that Cleopatra used to bathe in sour milk to help reduce wrinkles.

Read more about some other popular AHA's here:

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.

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

Due to its exfoliating properties, you should wear SPF when using Malic Acid.

Fun fact: The word "Malic" comes from the word "Malum". In Latin, "Malum" means apple. This ingredient is often derived from unripe fruit.

Read more about some other popular AHA's here:

Sodium Hyaluronate is naturally occurring in our bodies and is mostly found in eye fluid and joints.

These are some other common types of Hyaluronic Acid:

Tartaric acid is not as well studied as other AHAs, such as glycolic acid.

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:

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!