Like salicylic acid, this ingredient is a chemical exfoliant that can help break down the oil in your pores and reduce inflammation.

Though studies for LHA do show it to be less effective than salicylic acid. To be fair, salicylic acid is the reigning monarch of acne treatments.

However, a study from 2009 found LHA to be comparable to BPO, making it a good alternative for people with sensitive skin. Another study of 14 patients found a significant decrease in comedones after using LHA.

Another pro of LHA? It is less irritating than salicylic acid due to its large molecule size.

Large molecules cannot penetrate skin as well, so they are gentler on the skin. LHA is much less penetrative than salicylic acid.

An in-vitro study (not done on a living organism) found only 6% of LHA penetrated past the statum corneum compared to 58% of salicylic acid. An in-vivo (done on a living organism) analysis revealed ~17% of LHA was still present in the top layer of skin after 4 days, versus ~9% of salicylic acid.

Interestingly, a study from 2008 found LHA comparable to another famous acid, glycolic acid.

This study found about 10% of LHA is as effective as 20-50% of glycolic acid in treating hyperpigmentation and fine-lines.

Hydroxy acids have been found to stimulate skin protein, lipids, and thermal thickening. This may have anti-aging benefits.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Read more about some other popular AHA's here:

What makes hyaluronic acid so hydrating? It has the capacity to bind or hold large amounts of water.

Fun fact: It is already naturally found in our bodies, such as the fluids of our eyes and our joints.

Studies find this ingredient to have anti-inflammatory and anti-microbial properties. This can help speed up wound-healing.

Hyaluronic acid can be irritating if the molecule has a low-molecular weight, or if the molecules are small.

One study found low-molecular weight hyaluronic acid to be pro-inflammatory, meaning some people may experience irritation. This is because our bodies use hyaluronic acid in the wound-healing process to signal to our bodies, via irritation, that something needs healing.

The same study found high-molecular weight hyaluronic acid to be anti-inflammatory.

These are some other common types of Hyaluronic Acid:

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:

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!