How to use them
Alternate nights, for example Lactic 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 Lactic Acid first, wait a few minutes, then apply PHA.
- 1CleanseGentle cleanser, pat dry
- AMLactic Acid (day 1)then moisturiser and SPF 50
- PMPHA (day 2)then moisturiser
What Lactic Acid does
A gentler AHA with a larger molecule. It exfoliates while also acting as a humectant, so it suits dry and sensitive skin that cannot tolerate glycolic acid.
- Typical strength
- 5% – 10%
- When
- PM
- Irritation
- Best for
- Dry, Normal And Sensitive skin
Everything that pairs with Lactic 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 Lactic Acid vs PHA: which is better for your skin.
Frequently asked questions
Can I use Lactic Acid and PHA together?
Yes, but not at the same time. Lactic 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, Lactic Acid or PHA?
Apply Lactic 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 Lactic Acid in the morning or at night?
Lactic Acid: best at night. Use 2–3 nights a week. It is good for beginners to exfoliation. Follow with a moisturiser, and wear SPF the next day.
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.