Bright Diary Stubborn Acne Cream Versus Dermalogica Deep Acne Invisible Liquid Patch

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.

This ingredient is typically used in concentrations between 1-10%. Studies have found it to be non-sensitizing, non-phototoxic, and non-photoallergenic.

A close cousin of this ingredient is Glyceryl Stearate SE ("self-emulsifying"). This just has a small amount of sodium or potassium stearate added so it can emulsify without a co-emulsifier.

Since this ingredient is an ester of a C18 fatty acid, it may not be fungal acne safe. The Malassezia yeast can potentially metabolize within the C11-C24 range.

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

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

One manufacturer claims this ingredient to have a pH range of 2-8 and to be biodegradable.

This ingredient is also known as Sepimax Zen.

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

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.

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