How much cysteamine do you need? 5%+
The effective cysteamine percentage, by the vehicle-controlled trials, starts at 5%; no published dose comparison sets a ceiling.
Give it eight to twelve weeks: that is when the change first became measurable.
how it was measured
Measured on Melasma severity (MASI) and melanin index by mexameter; the first visit at which the change was measurable.
What cysteamine percentage is effective?
Every trial uses 5%.
5%+
The trials, and what they used
- Cysteamine 5% cream, applied at bedtime for a short contact, beat placebo cream on mexameter contrast and MASI at 2 and 4 months in 50 patients with epidermal melasma (Mansouri 2015, double-blind, the maker co-authoring) and again in 40 patients read by Dermacatch and Mexameter (Farshi 2018).
- Against 4% hydroquinone it lost on mMASI, 38% against 53% at 120 days in 40 women, with erythema and burning the common complaints (Lima 2020).
- No dose comparison found; 5% is the only concentration ever tested and the only one sold, so the floor and the product are the same number.
Is more than 5% cysteamine better?
Nobody has measured it: no published dose comparison sets a ceiling for cysteamine, so a percentage above 5% is above the trials' floor, not above a measured maximum. Only one strength has ever been tested, 5% (Lima 2020), and the paper reports more irritation there.
Erythema and burning were the most important local adverse effects with cysteamine, although their frequency did not differ between groups (P > 0.170).
The highest dose tested, in the paper’s words
- Erythema and burning were the most important local adverse effects with cysteamine, although their frequency did not differ between groups (P > 0.170).
No published dose comparison sets a ceiling for cysteamine. A declared percentage above 5% is above the trials' floor, not above a measured maximum: the trials say from 5% it works, and say nothing about whether more does more.
What does the cysteamine percentage on a label tell you?
A name that states a percentage ("Cysteamine 5%") is the only amount a cosmetic label ever declares, so it is the one number that can be read against the trials: at or above the 5% floor, or below it.
A name without a percentage leaves the position. The rules make a brand list ingredients in descending order of amount down to 1%, and in any order below it, so cysteamine above the 1% line is at least 1% and cysteamine below it can be any trace the brand likes. The floor the trials worked from is 5%, and a position alone cannot tell you whether a label reaches it.
The cysteamine percentages in our catalogue
No product in our catalogue is sold on cysteamine yet.
Read on
- Cysteamine: the glossary page what it does, who it suits, where it fits
- Cysteamine vs Niacinamide
- Cysteamine vs Vitamin C (LAA)
- Cysteamine vs Retinal
- Cysteamine vs Hydroxypinacolone Retinoate
- Cysteamine vs Retinyl Retinoate
- Cysteamine vs Azelaic Acid
Other actives with a dose the trials pinned:
- Niacinamide 2%+
- Vitamin C (LAA) 5%+
- Retinol 0.075 to 0.3%
- Salicylic acid (BHA) 0.5%+
- Lactic acid 8%+
- Glycolic acid 5%+
- Retinal 0.05 to 0.1%
- Retinyl Retinoate 0.06%+
- Tretinoin 0.025%+
- Adapalene 0.1%+
- Tazarotene 0.045%+
- Azelaic Acid 15%+
- THD Ascorbate 1%+
- Sodium Ascorbyl Phosphate 5%+
- Palmitoyl Pentapeptide-4 0.0003%+
- Caffeine 2%+
- Benzoyl Peroxide 2.5 to 5%
- Tea Tree Oil 5%+
- Hydroquinone 4%+
- Bifida Ferment Lysate 10%+
- Thiamidol 0.2%+
- Menthol 0.1 to 5%
- Peppermint Oil 0.5%+
- N-Acetyl Glucosamine 2%+
- Alpha Lipoic Acid 5%+
- Ammonium lactate 12%+
- Acetylated Hyaluronic Acid 0.1%+
- 4-n-Butylresorcinol 0.1%+
- 4-t-Butylcyclohexanol 0.4%+
- Sphingomonas Ferment Extract 2%+