Cysteamine
Can reduce melasma pigmentation in tested topical formulas.
Key facts
Cysteamine at a glance.
Helps with
Melasma
Results
Assess at 8–16 weeks
Skin tolerance
Odor, stinging or irritation
Routine fit
Follow wash-off instructions
At a glance
Top things to know about Cysteamine
- What it is. Pigment-targeting active.
- What it does. Can reduce melasma pigmentation in tested topical formulas.
- What limits the claim. A small placebo-controlled study supports 5% cream over four months. Active-comparator studies are small and do not prove equal efficacy to hydroquinone. The mass shown refers to the free base, not its hydrochloride salt.
- Choosing a formula. Consider for diagnosed melasma when a suitable topical option is needed.
More details: strength, timing and precautions
| Bottom line | Consider for diagnosed melasma when a suitable topical option is needed. |
|---|---|
| Type | Pigment-targeting active |
| What it does | Can reduce melasma pigmentation in tested topical formulas. |
| Best for | Melasma |
| Studied concentrations | 5% cream in controlled melasma trials; contact instructions vary by product. |
| When to use | On the schedule specified for the product or prescribed treatment. |
| Time to results | Usually assessed over 8–16 weeks |
| Irritation | Odour, stinging and irritation may limit use; follow wash-off instructions. |
| Sensitive skin | Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it. |
| Available | Prescription or cosmetic status depends on the active, formula and country; check the label. |
Often used for
What Cysteamine is used for
Melasma
A placebo-controlled trial found reduced pigmentation with 5% cream.
Post-Inflammatory Hyperpigmentation
The cited melasma trial does not establish fading of every type of dark mark.
Vitiligo
The reviewed sources do not establish this ingredient as a treatment for this concern.
Sensitive Skin
The reviewed sources do not establish this ingredient as a treatment for this concern.
HOW IT WORKS
How Cysteamine works
Diagram explanation and sources
Affects melanin formation: Cysteamine acts through several pigment pathways. May help melasma: The formula, contact time and tolerance matter.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Strengths
Cysteamine strengths
5% cysteamine cream is the main concentration studied for melasma. Contact time is product-specific; some studied formulas are short-contact treatments rather than overnight creams.
5%
Controlled trials studied this strength. One short-contact trial used a specific cream; follow the current product’s instructions rather than copying a study schedule.
Choosing a strength: Choose a finished topical product with clear instructions for how long to leave it on and when to rinse.
Higher strengths: There is no established benefit from escalating beyond the studied strength. Burning, redness or a persistent rash are reasons to stop and reassess.
Formula matters: Stabilization, the base cream and exposure time affect tolerability. Different cysteamine formulations need not have identical instructions.
Forms
Cysteamine forms
Cream
Richer and more moisturizing; often suits dry skin. The full formula still affects comfort.
Products
Product examples
No product example is linked in the old Dermapedia table.
How to use it
When to use
On the schedule specified for the product or prescribed treatment.
How to apply
Follow the product’s contact time and wash-off directions; protocols differ. Avoid eyes and irritated skin.
Moisturizing
Use a simple moisturizer if needed; for rich oils or balms, start with a small amount.
Tolerance
Odour, stinging and irritation may limit use; follow wash-off instructions.
If it is not working
Reassess after roughly 8–12 weeks, or sooner for worsening symptoms. Persistent pigment, acne or a rash may need a different treatment.
Sun protection
Use broad-spectrum SPF 30 or higher each morning, especially when treating uneven pigmentation.
What to expect
First few weeks
Assess tolerance first; pigment change is usually slower.
4–8 weeks
Some studied regimens begin showing pigment improvement.
8–12 weeks
A useful review point for benefit and irritation.
3–6 months
Many melasma trials assess results over three to four months; recurrence is common.
6–12 months
Long-term use depends on the active; follow a monitored plan rather than extending treatment automatically.
What it pairs with
| Ingredient | Use | What to know |
|---|---|---|
| Moisturizer | As needed | Choose a simple formula that improves comfort. |
| Sunscreen | Each morning | Use a tested broad-spectrum product; do not mix other skincare into it. |
| Other active treatments | Introduce separately | Compatibility does not prove an added benefit. Seek a treatment plan when combining medicines. |
Alternatives
Alternatives
Hydroquinone
The standard cysteamine is measured against. Head-to-head trials suggest broadly comparable results over a few months. Hydroquinone needs a prescription in the United States and is used in courses; cysteamine can be used for longer but smells strongly.
Azelaic acid
Gentler, cheaper, no smell, and it treats acne and rosacea at the same time. Slower and weaker on established melasma.
Tranexamic acid
Stronger for the oral form than for the cream. Often combined with topicals. Oral use requires medical supervision because of clotting risk.
Topical retinoids
For pigment over the long term. Slower, and they irritate in a different way. Not used in pregnancy.
Chemical peels and lasers
Heavily dependent on who is doing them. Faster when they work, and capable of making melasma worse when they do not, especially in deeper skin tones.
Vitamin C and niacinamide
Limited to moderate evidence. Useful for maintenance and easy to tolerate, but not a match for cysteamine on active melasma.
Safety and cautions
Common reactions
Odour, stinging and irritation may limit use; follow wash-off instructions.
When to stop
Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.
Sensitive or inflamed skin
Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.
Important limits
Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.
Pregnancy
Not stated in existing content
Questions
Questions you might be asking.
What should I choose cysteamine for?
Consider for diagnosed melasma when a suitable topical option is needed.
How strong is the evidence?
A small placebo-controlled study supports 5% cream over four months. Active-comparator studies are small and do not prove equal efficacy to hydroquinone. The mass shown refers to the free base, not its hydrochloride salt.
Sources
Sources and further reading
Research updated 2026-10-25. Evidence grades reflect confidence in a specific benefit, not its size.
Related
Keep exploring.
Hydroquinone
Melasma
Post-Inflammatory Hyperpigmentation
Tranexamic Acid
Azelaic Acid
Vitiligo
Azelaic Acid vs Cysteamine
Cysteamine vs Hydroquinone
Cysteamine vs Tranexamic Acid
Alpha Arbutin vs Cysteamine
Cysteamine vs Kojic Acid
