Ingredient glossary
Cysteamine
On your shelf ✓What Cysteamine does for your skin, who it suits, and what to watch for.
INCI: Cysteamine · Also: Cysteamine Hydrochloride
In short: Cysteamine delivers brightening and antioxidant, earns its place for pigmentation and melasma, and the evidence behind it is strong. One thing to know: not for pregnancy or breastfeeding; introduce it gently.
- What it does
- Brightening, antioxidant
- Best for
- Pigmentation, melasma
- Watch out
- Not for pregnancy or breastfeeding; introduce it gently
- Evidence
- Strong
- How long
- 8–12 weeks
The molecule
The Glow take
One of the ingredients I trust most.
When your goal is fading dark spots and evening out tone, Cysteamine delivers, and the research properly backs it up. Skip it while you are pregnant or breastfeeding, and the rest of the time bring it in slowly.
— Maya
What it does
- brightening
- antioxidant
strong evidenceMultiple randomized trials and a systematic review show five percent cysteamine cream significantly reduces melanin indices and MASI scores and can match or outperform hydroquinone-based formulas with mostly mild reversible side effects.
On a label: usually effective at 5%.
Who it's for, and who should skip it
Tends to suit
- pigmentation
- melasma
- postinflammatory hyperpigmentation
Approach with care
- pregnancy
- breastfeeding
- very sensitive
- compromised barrier
- Clogs poresLow
- Irritation riskModerate
How it fits each skin type
- DryNeutral
- CombinationNeutral
- OilyNeutral
- SensitiveTake care
Often chosen for pigmentation, melasma, postinflammatory hyperpigmentation. Take extra care if any of these apply to you: pregnancy, breastfeeding, compromised barrier.
Where it fits in your routine
Give it eight to twelve weeks — that is when the change first became measurable.
What was measured, and in whom
Measured on: Melasma severity (MASI) and melanin index by mexameter.
The vehicle-controlled randomised trial of 5% cysteamine cream in epidermal melasma, applied as a nightly short-contact regimen, ran four months with assessments at two and four months; MASI and melanin index were significantly better than placebo at the two-month visit, the earliest point measured, and improved further by four months. 5% is also the marketed strength, so the number transfers to what people actually buy, though the population was Fitzpatrick III-IV epidermal melasma rather than mixed or dermal disease. Later 16-week comparisons against 4% hydroquinone and triple-combination cream agree on the size of the effect.
Randomised double-blind placebo-controlled trial of cysteamine 5% cream in epidermal melasma reported by Mansouri and colleagues (Br J Dermatol, 2015); described rather than cited, PMID not verified.
Plays well with
- sunscreens
- vitamin c
- niacinamide
Cysteamine, answered
Is Cysteamine safe during pregnancy?
No. Cysteamine is best avoided during pregnancy and breastfeeding. If you are pregnant or trying, leave this one out and ask your doctor about a safe alternative.
Who should avoid Cysteamine?
Approach Cysteamine with care if any of these apply to you: pregnancy, breastfeeding, very sensitive, and compromised barrier. Its irritation risk is moderate, so introduce it slowly and patch test first.
What concentration of Cysteamine actually works?
Cysteamine tends to be effective at around 5%. Much lower and it is likely underdosed.
During pregnancy
Leave Cysteamine out while you are pregnant or breastfeeding. It sits on the list of ingredients usually held back during this time.
When in doubt, check with your doctor or midwife. They outrank any website, including this one.When it is worth booking →
Compare Cysteamine with
- Niacinamide
- Vitamin C (LAA)
- Retinal
- Hydroxypinacolone Retinoate
- Retinyl Retinoate
- Azelaic Acid
- Tranexamic Acid
- Kojic Acid
- Phytic Acid
- THD Ascorbate
- Sodium Ascorbyl Phosphate
- Magnesium Ascorbyl Phosphate
- Ascorbyl Glucoside
- Ethyl Ascorbic Acid
- GHK-Cu
- Bakuchiol
- Alpha Arbutin
- Caffeine
- Hydroquinone
- Galactomyces Ferment Filtrate
- Rice Extract
- Thiamidol
- N-Acetyl Glucosamine
- Tetrahydrocurcumin
- Exosomes
- Epidermal Growth Factor
- Carnosine
- 4-n-Butylresorcinol
- 4-Hexylresorcinol
Can you mix Cysteamine with
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.