Cysteamine

What is cysteamine and what does it do?

Cysteamine is a small sulphur-containing molecule produced in the body during the breakdown of the amino acid cysteine. In skin, it interferes with melanin production at several steps, including tyrosinase and peroxidase activity, and shifts pigment synthesis away from dark eumelanin. Topical cysteamine creams are usually applied for a short contact time, often 15 minutes to a few hours, then washed off, because longer contact increases irritation. It is used mainly for melasma and other stubborn epidermal pigmentation, often as an alternative or follow-on to hydroquinone. It has a noticeable odour, which some users find off-putting. [1]

What does the evidence show?

Randomised controlled trials, mostly small and of short duration, show 5% cysteamine cream reduces melasma severity compared with placebo. Systematic reviews and meta-analyses suggest it performs better than vehicle and broadly comparably to some hydroquinone-based regimens, but the studies are heterogeneous and several have small samples. Long-term data on relapse and maintenance are limited, so it is better seen as one evidence-supported option within a wider melasma plan.

Who should avoid cysteamine?

Cysteamine commonly causes redness, burning, dryness and itching, especially in the first weeks, so people with very sensitive skin, eczema or a damaged skin barrier may not tolerate it. It should not be applied to broken skin. Use in pregnancy and breastfeeding has not been well studied and should be discussed with a doctor first.

Is cysteamine available in Singapore?

Topical cysteamine creams are marketed in several countries as cosmetic products, and availability in Singapore depends on the specific brand and how it has been notified. Oral cysteamine is a separate prescription medicine for a rare metabolic condition. It depends on the product, so check with a doctor or pharmacist before buying online.

If a dark patch, breakout or irritation is not responding to what you are using, the next step is a diagnosis rather than another product. See the Skin A–Z library for related ingredients.