TIRTIR PHA 15% Serum: The Gentler Acid Exfoliant for Sensitive Skin

PHA (polyhydroxy acid) is the milder cousin of AHA and BHA in the chemical exfoliation category. The molecules are larger, which means they penetrate the skin more slowly and cause less irritation than glycolic acid or salicylic acid at equivalent concentrations. TIRTIR's PHA 15% Serum leverages this property to deliver daily-wearable exfoliation for users whose skin can't tolerate stronger acids. The 15% concentration is functional (many PHA products use 3 to 8%) while remaining gentler than a 10% AHA serum.

At $43 for 30ml, this is upper-mid-range for a Korean acid serum. The price reflects the high PHA concentration and TIRTIR's overall premium positioning. For users with reactive or sensitized skin who've failed on AHA/BHA, this opens exfoliation as a category again. For users with robust skin who tolerate glycolic or salicylic acid, PHA works but more slowly; you may prefer the faster-acting alternatives.

What It Does

PHA at 15% delivers slow, gentle surface exfoliation, breaking down the bonds between dead skin cells on the surface layer. Over 4 to 6 weeks of daily use, skin texture smooths, pore appearance reduces, and tone evens. PHA also has humectant properties (it draws moisture into skin), which is unusual for an exfoliating acid; most acids dry skin during the exfoliation process. This cream serum hydrates while it exfoliates, reducing the typical flaking or tightness of acid use.

Who It's For

• Sensitive skin that can't tolerate AHA/BHA: Primary target; PHA is the sensitive-skin chemical exfoliant.
• Rosacea-adjacent skin: Lower reactivity than stronger acids.
• Post-procedure exfoliation: Safer reintroduction of exfoliation after laser or peel.
• Retinol users wanting complementary exfoliation: PHA layers well with retinol without over-exfoliating.
• First-time exfoliant users: Lower-risk entry into chemical exfoliation.

Key Specs

• Volume: 30ml
• Price: $43
• Hero active: PHA (polyhydroxy acid) at 15%
• Texture: lightweight serum
• Fragrance: low
• pH: skin-matched, non-stinging

How to Use

After cleansing and toner, apply 2 to 3 drops to face and neck. Let absorb 60 seconds, then layer moisturizer. Use PM daily; or AM and PM once tolerance is established. PHA is less photosensitizing than AHA but still benefits from consistent SPF use in the morning. Do not combine with strong retinol (0.5% or higher) in the same evening; alternate nights.

For acclimation: start 3 times per week for 2 weeks, then increase to daily. Some mild tingling on first application is normal; persistent burning or peeling means reduce frequency.

FAQ

Is PHA 15% as effective as AHA 10%?

Different speeds. PHA works more slowly because the larger molecules penetrate gradually. Over 4 to 6 weeks, PHA 15% can deliver comparable results to AHA 10% with less irritation. For fast visible change: AHA. For gentle consistency: PHA.

TIRTIR PHA vs Dr.Jart Pore Remedy PHA?

Both are PHA serums at similar price points. TIRTIR is 15%, Dr.Jart is typically lower concentration with pore-specific focus. TIRTIR is more exfoliation-forward; Dr.Jart is more pore-treatment-forward. For general exfoliation: TIRTIR. For pore-specific concern: Dr.Jart.

Can I use this with vitamin C?

Yes, with spacing. Vitamin C AM, PHA PM works cleanly. Same-routine application can cause mild reactivity on sensitive skin; test carefully. Robust skin can layer both same-session (vitamin C first, wait 10 minutes, then PHA).

Will it cause purging?

Mild purging possible in the first 1 to 2 weeks as PHA accelerates surfacing of pre-existing pore congestion. Less dramatic than BHA-triggered purging. Resolves within 3 to 4 weeks.

Is it safe for daily use?

Yes, after acclimation. PHA is the most daily-tolerant of the exfoliating acids. Many users do twice-daily application long-term without irritation. Monitor your skin; if dryness or sensitivity develops, reduce frequency.

Related Products

Pair with COSRX Advanced Snail 92 All in One Cream for post-exfoliant barrier support, or Dr.Jart Pore-remedy PHA Exfoliating Serum as a pore-focused alternative.

Browse the full TIRTIR collection or related: Korean exfoliating serums.