The Derma Co 2.5% Benzoyl Peroxide Spot Corrector

Concentrations up to 100% in guinea pig tests found it to be non-sensitizing and completely safe for use in cosmetics.

Safety-wise, a panel of independent toxicologists reviewed this ingredient and concluded it to be safe in cosmetics in the present practices of use and concentration.

A separate sensitization patch test on humans also showed no evidence of allergic reactivity, and a true allergy to this ingredient is considered rare.

Typical usage levels range from 0.015%-3% in leave-on products and 0.078%-3.2% in rinse-off products.

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 top of that, BPO has keratolytic properties to help shed dead skin cells and keep pores from getting clogged.

One of the coolest things about BPO is that bacteria do not develop resistance to it the way they can with antibiotics. That's why dermatologists recommend pairing it with topical antibiotics to keep resistance at bay.

BPO is usually available in 2.5%, 5%, and 10% concentrations. Research has shown that 2.5% tends to be just as effective as the higher strengths while being more gentle on the skin.

The FDA has classified BPO as a safe and effective acne treatment. You'll be able to find this ingredient in over-the-counter products in many countries.

Just so you know, BPO is a known mild irritant. It's common to see dryness, peeling, and some redness when you first start using it. This usually goes away as your skin adjusts.

A very small number of people might develop allergic contact dermatitis from it as patch test studies show positive reactions in about 1-5% of patients.

Once BPO is absorbed into the skin, our bodies turn it into benzoic acid and quickly exits in urine. It's also worth noting that BPO will bleach fabrics and hair, so watch your towels and pillowcases!

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.

The CIR Expert Panel has evaluated the scientific data and found this ingredient to be safe, non-irritating, and non-sensitizing at concentrations up to 5% (it's even approved by the FDA as an OTC eye drop ingredient).

The zinc part slows down an enzyme that turns testosterone into DHT, the hormone that tells your oil glands to pump out more sebum. Less of that signal means less oil. It also gently fights acne-causing bacteria and soothes redness/irritation.

This is why Zinc PCA often shows up in products for oily, breakout-prone skin and greasy scalps.

One lab study also hinted it might have a small anti-aging perk because it seemed to protect collagen from UVA damage and even helped the skin make a bit more of it. That last bit is still early research done in a dish and not real skin, so take it as a nice bonus rather than a promise for now.

As for scar healing, the picture is more "maybe" than a firm yes. Zinc itself plays a real role in wound repair because it is a cofactor for the enzymes involved in collagen building, calming inflammation, and helping new skin cells cover a wound. Lower zinc levels are also linked to slower healing.

Most of the scar healing research is on zinc oxide or oral zinc rather than zinc PCA specifically, with a focus on healing fresh wounds instead of scars that are already there.

Direct evidence that zinc PCA improves the look of established scars is still limited at this time. Though it would be fair to say zinc PCA supports the general skin-repair environment thanks to its zinc content .

This ingredient is water-soluble and plays nicely with other actives like niacinamide and salicylic acid. It works best at mildly acidic formulas (~4-6 pH) and is effective at low levels. Around 0.1% is enough to be active and finished products commonly use it anywhere up to 4%.

Overall, this is a well-tolerated, low-drama multitasker that suits oily and acne-prone skin.

Research shows it can encourage your skin cells to turn over and renew by stimulating keratinocyte and fibroblast proliferation.

It also has mild keratolytic properties to help loosen and shed dead skin cells without being harsh.

Studies also suggest allantoin can help calm inflammation by dialing down some of the chemical signals your skin sends out when it is irritated.

This ingredient is typically used in the 0.1-0.5% range, and the FDA recognizes it as a skin protectant in OTC products up to 2%.

Overall, allantoin is a wonderful addition to most routines; it is stable across a wide pH range (~4-8), works well with other ingredients, and is considered non-sensitizing/non-irritating.

Fun fact: Allantoin is naturally occurring in comfrey root, beets, chamomile, and wheat sprouts. Our bodies even produce it as a byproduct of uric acid metabolism.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

The antioxidant properties help protect your body from free-radicals. Free-radicals are molecules that may damage your skin cells. As a result, ginger may help slow down signs of aging such as hyperpigmentation and wrinkles.

Studies show ginger inhibits the enzyme that breaks down collagen. It also helps with:

This ingredient has no negative side-effects and is safe to use unless one has a specific allergy to it.

Ginger originates from Southeast Asia but has spread throughout the world. It is now a common spice used in many cultures.

On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.

One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).

Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.

You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.

Human patch tests with a facial lotion containing 1% of this ingredient found no sensitization.

The unique structure of silica enhances the spreadability and adds smoothness, making it a great texture enhancer.

It is also used as an active carrier, emulsifier, and mattifier due to its ability to absorb excess oil.

In some products, tiny microneedles called spicules are made from silica or hydrolyzed sponge. When you rub them in, they lightly polish away dead skin layers and enhance the penetration of active ingredients.

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.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.