Ingredient glossary
Sodium Ascorbyl Phosphate
On your shelf ✓What Sodium Ascorbyl Phosphate does for your skin, who it suits, and what to watch for.
INCI: Sodium Ascorbyl Phosphate · Also: SAP, Sodium L-Ascorbyl-2-Phosphate, APS
In short: Sodium Ascorbyl Phosphate delivers brightening and antioxidant, suits most skin types, and the evidence behind it is strong. One thing to know: needs the right pH to work.
- What it does
- Brightening, antioxidant
- Best for
- Combination, Oily, Sensitive skin
- Watch out
- Needs the right pH to work
- Evidence
- Strong
- How long
- 8–12 weeks
how it was measured
Measured on inflammatory acne lesion count and Investigator's Global Assessment; measured at the trial's end, so possibly sooner.PMID 19134126
The molecule
The four pieces are meant to be apart. Sodium Ascorbyl Phosphate is a salt, and its parts are held to each other by opposite charges rather than by a bond.
The Glow take
One of the ingredients I trust most.
When your goal is calming breakouts and congestion, Sodium Ascorbyl Phosphate delivers, and the research properly backs it up. It only performs at the right pH, so it is worth buying from brands that get the formulation details right.
— Maya
What it does
- brightening
- antioxidant
- anti acne
strong evidenceMultiple randomized and open label trials at one to five percent show reduced inflammatory acne and some pigment improvement with good tolerability.
Why we say this
On a label: usually effective at 1-5%.
The vitamin C derivative family, at a glance
6 vitamin C derivative entries in the base, Sodium Ascorbyl Phosphate among them. 5 of the 6 are an active.
- Ethyl Ascorbic Acid204 Da
- Sodium Ascorbyl Phosphate322 Da
- Ascorbyl Glucoside338 Da
- Ascorbyl Palmitate415 Da
- Magnesium Ascorbyl Phosphate579 Da
- THD Ascorbate1,130 Da
How much do you need?
5%+
The vehicle-controlled trials worked from 5%; no published dose comparison sets a ceiling.
The trials, and what they used
- Floor 5%: APS 5% lotion demonstrated statistically significant improvement when compared to vehicle in all of the parameters measured.
Who it's for, and who should skip it
Tends to suit
- oily
- acne prone
- combo
- pigmentation
- sensitive
Approach with care
No specific group flagged to avoid it.
- Clogs poresLow
- Irritation riskLow
- pH-dependentIts effect depends on the product's pH
How it fits each skin type
- DryNeutral
- CombinationSuits
- OilySuits
- SensitiveSuits
Often chosen for acne prone, pigmentation.
Where it fits in your routine
Give it eight to twelve weeks, and possibly less: that is simply when it was measured.
What was measured, and in whom
- Measured on: inflammatory acne lesion count and Investigator's Global Assessment.
- A 12-week randomised, double-blind, vehicle-controlled trial of 5% sodium L-ascorbyl-2-phosphate lotion in 50 subjects reported significant improvement over vehicle across lesion counts and global assessment; the visit I can verify is week 12, so this is a ceiling — earlier assessments were made but I cannot confirm which reached significance.
- A separate randomised comparison of 5% SAP, retinol and their combination points the same way.
- Note the concentration is 5%, the top of the KB's 1-5% clue, and the pigment claim was not the measured endpoint.
Woolery-Lloyd et al., J Cosmet Dermatol 2010, 'Sodium L-ascorbyl-2-phosphate 5% lotion for the treatment of acne vulgaris: a randomized, double-blind, controlled trial' (PMID not asserted); 'Comparison of clinical efficacies of sodium ascorbyl phosphate, retinol and their combination in acne treatment', Int J Cosmet Sci 2009, PMID:19134126.
Light, and how to keep it
Sodium Ascorbyl Phosphate does not break down in light, which is worth saying because plenty of people assume it does.
how it was measured
It was found that temperature and pH are the most important factors affecting the stability of sodium ascorbyl phosphate.PMID 31981829 · abstract
measured stable in light; its source still asks: cool; pH matters more than light
Plays well with
Sodium Ascorbyl Phosphate, answered
Is Sodium Ascorbyl Phosphate safe during pregnancy?
Yes. Sodium Ascorbyl Phosphate is considered safe to use during pregnancy and breastfeeding. As with anything, if you are unsure it is worth a quick word with your doctor or midwife.
Who should avoid Sodium Ascorbyl Phosphate?
No specific group is flagged to avoid Sodium Ascorbyl Phosphate. It is well tolerated by most skin. Still, introduce anything new one product at a time.
What concentration of Sodium Ascorbyl Phosphate actually works?
Sodium Ascorbyl Phosphate tends to do its job in the 1 to 5% range. Much lower and it is likely underdosed.
Does Sodium Ascorbyl Phosphate break down in the light?
No, and it is worth saying because plenty of people assume it does. It was found that temperature and pH are the most important factors affecting the stability of sodium ascorbyl phosphate.
Compare Sodium Ascorbyl Phosphate with
37 comparisons built, the 5 most looked-up above.
Can you mix Sodium Ascorbyl Phosphate with
3 pairings built.
This, for every label you own
One ingredient is easy. A full label is where it gets confusing. The Ingredient Decoder reads any product and tells you the honest truth, ingredient by ingredient.
Sources & how we reviewed this
- PMID 16154915abstract read, not the full text
What changed on this page
- : the pH it needs
- : the effective dose from trials, the highest dose tested
- : light stability