Cysteamine
An aminothiol and tyrosinase inhibitor. With a 5% cream melasma improved more than with placebo, but comparisons with 4% hydroquinone showed no advantage. Redness, burning and itching were more frequent than with placebo
Evidence by route
Topical application
For melasma there are placebo-controlled RCTs, but both come from one group with a co-author from the cream's manufacturer. Independent groups compared 5% cysteamine with 4% hydroquinone and found no difference or a difference in favor of hydroquinone. For post-acne pigmentation there is one RCT without placebo, and post-laser pigmentation has not been studied
- B
Brightening
In two placebo-controlled RCTs by one group with a co-author from the manufacturer, MASI at 4 months was lower than with placebo (7.2 vs 11.6 in Mansouri 2015). Independent comparisons with 4% hydroquinone found no difference or favored hydroquinone
- B
Post-acne pigmentation
In one RCT of 28 patients, post-acne pigmentation decreased equally with 5% cysteamine and with 4% hydroquinone plus 3% ascorbic acid. There was no placebo, and a co-author holds shares in the manufacturer
- D
Pigmentation after laser procedures
No studies have tested cysteamine for pigmentation after laser procedures
- Mansouri P et al. Evaluation of the efficacy of cysteamine 5% cream in the treatment of epidermal melasma: a randomized double-blind placebo-controlled trial. Br J Dermatol. 2015;173(1):209-17. PMID 25251767
- Farshi S et al. Efficacy of cysteamine cream in the treatment of epidermal melasma, evaluating by Dermacatch as a new measurement method: a randomized double blind placebo controlled study. J Dermatolog Treat. 2018;29(2):182-189. PMID 28678558
- Lima PB et al. A comparative study of topical 5% cysteamine versus 4% hydroquinone in the treatment of facial melasma in women. Int J Dermatol. 2020;59(12):1531-1536. PMID 32864760
- Karrabi M et al. Clinical evaluation of efficacy and tolerability of cysteamine 5% cream in comparison with tranexamic acid mesotherapy in subjects with melasma: a single-blind, randomized clinical trial study. Arch Dermatol Res. 2021;313(7):539-547. PMID 32879998
- Sepaskhah M et al. Comparison of the efficacy of cysteamine 5% cream and hydroquinone 4%/ascorbic acid 3% combination cream in the treatment of epidermal melasma. J Cosmet Dermatol. 2022;21(7):2871-2878. PMID 35510765
- Kusumawardani A et al. Efficacy of overnight leave-on sandwich therapy with 5% cysteamine and ectoine cream compared to hydroquinone 4% cream for treatment of melasma: a double-blind randomized controlled trial. Acta Dermatovenerol Alp Pannonica Adriat. 2025;34(1):1-4. PMID 40127492
- Ahmadi K et al. Assessing the Effectiveness of Stabilized Cysteamine 5% Cream Compared to Hydroquinone 4%/Ascorbic Acid 3% Combination Cream in Treating Acne-induced Post-inflammatory Hyperpigmentation: A Randomized, Controlled Study. J Clin Aesthet Dermatol. 2024;17(4):37-41. PMID 38638185
- Tsai YW et al. Efficacy and Safety of Combination Therapy of Microneedling Radiofrequency, In-Office and Home-Based Topical Cysteamine in Refractory Melasma: A Split Face, Vehicle-Control, Randomized Control Trial. J Cosmet Dermatol. 2025;24(2):e16661. PMID 39574411
- Wu BQ et al. Clinical Efficacy of Cysteamine Application for Melasma: A Meta-Analysis. J Clin Med. 2024;13(23). PMID 39685940
- Karrabi M et al. Clinical evaluation of efficacy, safety and tolerability of cysteamine 5% cream in comparison with modified Kligman's formula in subjects with epidermal melasma: A randomized, double-blind clinical trial study. Skin Res Technol. 2021;27(1):24-31. PMID 32585079
- Nguyen J et al. Evaluation of the efficacy of cysteamine cream compared to hydroquinone in the treatment of melasma: A randomised, double-blinded trial. Australas J Dermatol. 2021;62(1):e41-e46. PMID 32981068
- Patil R et al. Comparison of the Effectiveness and Safety of 5% Cysteamine and 2% Kojic Acid Creams in the Treatment of Melasma in Indian Adult Females. Cureus. 2025;17(3):e81330. PMID 40296942
- Mawu FO et al. Efficacy and safety of cysteamine 5% cream for the management of melasma: a systematic review and meta-analysis of randomized controlled trials. Arch Dermatol Res. 2024;317(1):117. PMID 39673630
How to read tiers A–F
- BLimited evidence. One RCT or several controlled studies with limitations
- DNo data, or very weak or conflicting data
Tolerability and safety
- Working concentrations
- All RCTs used a 5% cream: at bedtime (Mansouri 2015), for 15 minutes once a day (Karrabi 2021, comparison with Kligman's formula) or overnight without rinsing (Kusumawardani 2025). In a meta-analysis, longer application added no benefit (Wu 2024)
- Irritation potential
- Medium
- Allergen risk
- Low
- Pregnancy
- Caution
- Suitable for
- Normal, Oily, Combination
- Use with caution
- Sensitive
About this ingredient
Cysteamine is an aminothiol with antioxidant properties and a tyrosinase inhibitor (Lima 2020, Mawu 2024). Melasma trials used it as a 5% cream. Both placebo-controlled RCTs of the cream without other procedures come from one group with a co-author from the manufacturer. In the first (50 patients, cream at bedtime for 4 months), the Mexameter difference between pigmented and normal skin fell from 75.2 to 26.2 with cysteamine and from 68.9 to 60.7 with placebo. Final MASI was 7.2 vs 11.6 (Mansouri 2015). The second RCT, in 40 patients, gave similar results (Farshi 2018). Independent groups compared cysteamine with active treatments. Against 4% hydroquinone, mMASI fell by 38% vs 53% over 120 days, while colorimetry did not differ (Lima 2020). Against a modified Kligman formula, mMASI at 4 months was 6.09 vs 7.04 in favor of cysteamine (Karrabi 2021). In a meta-analysis of 7 RCTs, cysteamine beat placebo and did not differ from 4% hydroquinone (Mawu 2024). In another meta-analysis the effect was no longer significant after correction for publication bias (Wu 2024). Erythema, irritation, burning, itching and dryness were more frequent than with placebo and as frequent as with hydroquinone (Mawu 2024). In one RCT hydroquinone was better tolerated (Nguyen 2021). The RCTs lasted up to 4 months, so long-term safety is unknown. There are no data on use during pregnancy and breastfeeding.
Frequently asked questions
Is Cysteamine safe during pregnancy?
Cysteamine should be used with caution during pregnancy. Consulting a dermatologist or OB-GYN is advisable.
What skin types is Cysteamine for?
Cysteamine suits: normal, oily, combination. Use with caution in: sensitive.
Can Cysteamine irritate the skin?
Cysteamine has moderate irritation potential. Sensitive skin may show a transient reaction that usually settles with adaptation.
What is Cysteamine and what does it do in cosmetics?
An aminothiol and tyrosinase inhibitor.
What's the INCI name for Cysteamine?
The INCI name is Cysteamine Hydrochloride. It may also appear as: Cysteamine.
What concentration of Cysteamine is effective?
All RCTs used a 5% cream: at bedtime (Mansouri 2015), for 15 minutes once a day (Karrabi 2021, comparison with Kligman's formula) or overnight without rinsing (Kusumawardani 2025). In a meta-analysis, longer application added no benefit (Wu 2024)
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