SkinCare by Roz

"Don't mix niacinamide with Vitamin C" is one of skincare's stickiest myths. Here's the truth: you can, and they're actually better together.

Where the myth came from: decades-old lab tests mixed the raw ingredients under high heat for a long time and made a compound that can flush the skin. That reaction needs a hot lab, not your bathroom shelf. On your face, at the strengths in real products, it simply doesn't happen.

What they actually do (two different jobs):
• Niacinamide (that's vitamin B3, usually 2–5%) rebuilds your moisture barrier, calms redness, evens tone, and helps keep oily skin in check.
• Vitamin C is your daytime antioxidant shield. It defends against sun and pollution damage, helps your skin build collagen, and fades dark spots a different way than niacinamide does.

The only real catch: piling two strong actives on at once can sting very sensitive skin. That's total "active load," not a chemical war. And if your Vitamin C has turned yellow-brown, it oxidized on its own and should be tossed. That's not the niacinamide's fault.

How to use them: one product with both is great. Prefer to layer? Vitamin C in the morning, niacinamide anytime, letting each soak in for a minute. Sensitive skin? Alternate days and build up slowly.

Tonight's carousel breaks the whole thing down: where the myth started, what each ingredient is really doing, and exactly how to layer them without the guesswork. Catch the evening post.

— Roz, Pharm.D. | consultant pharmacist

Mandelic or azelaic? Half of you are using the wrong one — and it's not because you bought a bad product. It's because nobody explained that these two aren't rivals. They do completely different jobs.

Mandelic acid is an exfoliator — and it's the gentlest one on the shelf. Here's why: it's the biggest AHA molecule, about twice the size of glycolic acid. A bigger molecule sinks in slowly and evenly, so it lifts off dead, pore-clogging skin without the sting. That makes it the one for rough texture, tiny bumps, congestion, and dullness — and because it's so gentle, it's the AHA of choice for sensitive skin and deeper skin tones, where harsher acids can actually trigger more dark spots.

Azelaic acid isn't an exfoliator at all. It works a completely different way: it calms redness, quiets the cells that pump out pigment, and fights acne bacteria — all without sloughing off a single skin cell. That's why it's the one for redness, rosacea-prone flushing, and the dark marks a breakout leaves behind.

So don't pick based on a video — match the acid to your skin. Rough and bumpy? Mandelic. Red and marked? Azelaic. Sensitive or a deeper skin tone? Both are safe. And if you want both, they layer beautifully.

Tonight's carousel has the full match-the-acid cheat sheet — exactly which one for which skin, plus how to use them together without wrecking your barrier. Catch the evening post.

— Roz, Pharm.D. | consultant pharmacist

You might be treating the wrong mark.

Here's something most people never learn: the marks a breakout leaves behind aren't all the same. Some are BROWN — that's leftover pigment, the same machinery that makes a freckle or a tan. And some are RED or pink — those aren't pigment at all. They're tiny blood vessels near the surface that got dilated while your skin was healing.

In the mirror they look almost identical. But they're two different problems — and they do not respond to the same products.

Try this, it takes one second: press the mark with a fingertip. If it turns pale and then the color floods back, it's a blood vessel — a red mark. If the color just sits there under your finger, it's pigment — a brown mark.

Why it matters: your brightening serums — vitamin C, arbutin, kojic acid — only work on pigment. On a red mark there is literally no pigment for them to fade, so you can use them for months and see nothing. That's not a bad serum. It's the wrong target. Red marks need calming, not brightening — and mostly they need time (most settle over a few months, not two weeks).

Tonight's carousel has the full cheat sheet — exactly which ingredient goes with which mark, and when it's a job for a dermatologist. Catch the evening post.

— Roz, Pharm.D. | consultant pharmacist

That "brightening" serum everyone's adding to cart? Tranexamic acid started out as a prescription drug for heavy bleeding.

Here's the backstory only a pharmacist tells you: oral tranexamic acid is an Rx medicine that helps blood clot — doctors use it for heavy periods and to control bleeding in surgery and dentistry. Dermatologists also prescribe it, at low doses, off-label for stubborn dark spots and melasma. The version in your serum is that same molecule, now sold as a topical cosmetic on the open drugstore shelf.

The part that settles half the comment section: it does NOT bleach your skin. After sun exposure, your skin fires a "make more pigment" signal — tranexamic acid quiets that signal, so you make less new pigment over time. Think dimmer switch, not bleach. That's also why it's a slow burn: weeks to months, not 14 days.

But it isn't for every mark, there's a safety line the trend videos skip, and how you layer it makes or breaks the result. Tonight's carousel breaks it all down — which marks it actually fades (and the one it does nothing for), what to pair it with, and the one question to ask your doctor first. Catch the evening post.

— Roz, Pharm.D. | consultant pharmacist

Your "acne" that won't quit might not be acne at all.

Those small, itchy bumps that show up in clusters — same size, no blackheads — on your forehead, hairline, chest, or back are often not bacterial acne. They're Malassezia folliculitis, a.k.a. "fungal acne": an overgrowth of a yeast that already lives on everyone's skin, down inside the hair follicle.

Here's why a pharmacist is the one who'll tell you this: it's a fungus, not bacteria. So the things you'd normally reach for — benzoyl peroxide, salicylic acid, and especially antibiotics — miss the cause. Worse, antibiotics can actually make it worse: clearing out the competing bacteria gives the yeast even more room to grow. That's how this hides in plain sight for years (on average, it's misdiagnosed for around five years before someone catches it).

The fix has been in the dandruff aisle the whole time. Anti-dandruff washes built on ketoconazole, selenium sulfide, or zinc pyrithione are antifungals — the same actives dermatologists reach for. Ketoconazole 1% has sat over-the-counter since 1997. Used as a short-contact wash, it works on the yeast your acne routine can't touch.

One honest caveat: this is control, not a cure — the yeast lives on all of us, so it can come back — and if you're unsure or it won't budge, have a dermatologist confirm it. Treating the wrong thing is exactly what keeps it going.

Tonight's carousel breaks down the 5 tells that separate fungal acne from regular acne — and exactly how to use the wash without wrecking your barrier. Catch the evening post.

— Roz, Pharm.D. | consultant pharmacist