Cysteamine: Uses, Evidence and Cautions

Cysteamine is a naturally occurring aminothiol used in short-contact creams to reduce excess pigment, mainly in melasma. It interferes with several steps of melanin production and is washed off after a set contact time to limit irritation. Small trials support it against placebo, and it sits within a wider melasma plan alongside sun protection.

Key Facts

What it is: A naturally occurring aminothiol used in short-contact creams to reduce excess pigment, mainly in melasma.
Also called: Cysteamine hydrochloride; mercaptamine
Pairs with: Sunscreen with visible-light protection, gentle moisturiser, tranexamic acid, niacinamide
Who should take care: 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.
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.

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]

Three small glass ampoules of clear and pale-blue solution standing on white marble

“Oral cysteamine is a separate prescription medicine for a rare metabolic condition.”
Dr Sin YongOn topical versus oral cysteamine

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.

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Questions Patients Actually Ask

What is Cysteamine used for?+

A naturally occurring aminothiol used in short-contact creams to reduce excess pigment, mainly in melasma.

Who should avoid Cysteamine?+

Can Cysteamine be combined with other skincare?+

It is commonly paired with Sunscreen with visible-light protection, gentle moisturiser, tranexamic acid, niacinamide; introduce one new active at a time and stop if irritation develops.

How is cysteamine cream used?+

Cysteamine is used in short-contact creams, which are washed off after a set contact time to limit irritation. Follow the product directions or your doctor's instructions, and do not leave it on for longer than directed. Redness, burning and dryness are common in the first weeks.

When should I see a doctor about melasma instead of treating it myself?+

See a doctor if pigment is persistent, spreading or you are unsure of its cause, since other conditions can look like melasma. Cysteamine sits within a wider melasma plan alongside sun protection, which a doctor can tailor. Severe irritation also needs review.

Medically reviewed by Dr Sin Yong, MBBS (NUS), MRCS (Edinburgh) · Last updated 7 October 2026 · Editorial policy

Availability in Singapore

Cysteamine does not appear on the prohibited or restricted annexes of the ASEAN Cosmetic Directive, and in Singapore topical cysteamine pigment correctors are generally supplied under the cosmetic framework rather than as registered medicines, often through doctors' clinics. The HSA does not set a concentration limit for it; marketed creams contain around 5%. Its distinctive odour and tendency to redden skin mean it is used in short contact rather than left on. A doctor assesses the type and depth of pigmentation before recommending cysteamine or a prescription alternative.