Glymed Plus Mattifying Sulfur Masque Versus Face Reality Skincare Sulfur Spot Treatment

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

When sulfur touches skin, it reacts with an amino acid in skin cells (called cysteine) to create cystine and hydrogen sulfide.

That hydrogen sulfide helps loosen dead skin cells to exfoliate. And here's a geeky detail: the smaller the Sulfur particles, the more they interact with skin and the better they work.

Sulfur also has antifungal and antibacterial activity, which is why you'll see it in both acne treatments and dandruff shampoos.

In the US, acne products can use 3-10% sulfur while dandruff products use 2-5%. It's also often paired with Sodium Sulfacetamide, and using that combo twice daily for 12 weeks reduced inflammatory acne spots by about 80%.

The most common complains are the smell and dryness. Otherwise, side effects are uncommon.

If you have a "sulfa" allergy, that's an allergy to sulfonamide drugs and this doesn't mean you'll react to elemental sulfur.

A 1972 study suggested sulfur might clog pores. Elemental sulfur caused some clogged pores on rabbit ears and human backs (though the researchers noted the effect was mild).

A 1978 follow-up tested this on 52 people. After six weeks of patches with 5% Sulfur, skin biopsies showed no link between Sulfur and clogged pores. The surprise? The base the Sulfur was mixed into was what caused clogged pores. Later reviewers also noted that other studies couldn't repeat the 1972 results.

So why does Sulfur have a comedogenic rating of 3?

That number comes from a 1989 rabbit ear study by dermatologist James Fulton, which gave a 3 to water-soluble sulfur specifically. Even so, a 3 isn't a big red flag. Fulton's own scale treats 2 to 3 as borderline.

Human testing has also proved that any finished product with a comedogenic ingredient won't automatically make you break out; it really comes down to concentration, formula, and your skin.