How to use them
Alternate nights, for example Glycolic Acid on Monday, Wednesday and Friday and PHA on Tuesday and Thursday, with a plain moisturiser night in between if your skin feels sensitive. If your skin is resilient and already used to both, you can try layering them: apply Glycolic Acid first, wait a few minutes, then apply PHA.
- 1CleanseGentle cleanser, pat dry
- AMGlycolic Acid (day 1)then moisturiser and SPF 50
- PMPHA (day 2)then moisturiser
What Glycolic Acid does
The smallest alpha-hydroxy acid, so it penetrates deepest. It dissolves the bonds between dead skin cells for smoother, brighter skin and fades marks, but it is the AHA most likely to sting.
- Typical strength
- 5% – 10%
- When
- PM
- Irritation
- Best for
- Normal, Oily And Combination skin
Everything that pairs with Glycolic Acid →
What PHA does
Polyhydroxy acids are the gentlest chemical exfoliants. They work only on the surface, hydrate at the same time, and are usually tolerated by sensitive and rosacea-prone skin.
- Typical strength
- 3% – 10%
- When
- AM/PM
- Irritation
- Best for
- Sensitive, Dry And Normal skin
Everything that pairs with PHA →
Trying to choose one? Read Glycolic Acid vs PHA: which is better for your skin.
Frequently asked questions
Can I use Glycolic Acid and PHA together?
Yes, but not at the same time. Glycolic Acid and PHA are both exfoliating acids. Layered together they can over-exfoliate, which shows up as stinging, shiny tight skin and breakouts. Pre-formulated blends are fine. Otherwise, use them on different nights.
Which goes first, Glycolic Acid or PHA?
Apply Glycolic Acid first, then PHA. The general rule is thinnest to thickest texture, and lowest pH first. For this pair, though, it is better not to layer them in the same routine at all.
Should I use Glycolic Acid in the morning or at night?
Glycolic Acid: best at night. Use 2–3 nights a week after cleansing. Skip it on nights you use retinoids. Sunscreen is non-negotiable because AHAs raise sun sensitivity.
Should I use PHA in the morning or at night?
PHA: works morning or night. You can use it daily. It is a good first acid, or a way to keep exfoliating on retinoid "rest" nights if your skin tolerates it.