Can Cysteamine Stay on Overnight for Melasma?

Before changing a cysteamine cream from a wash-off treatment to overnight use, take its full directions to your dermatologist. A percentage on a tube leaves several questions unanswered: the formulation, what goes underneath it, contact time and how irritation will be monitored.

What the overnight study tested

The Indonesian trial randomized 80 women with melasma and Fitzpatrick skin types III–V, excluding menopause, pregnancy and breastfeeding. Seventy-seven completed: 40 on cysteamine, 37 on hydroquinone, with three lost from the latter arm.¹

Both evening routines layered ectoine beneath 5% cysteamine or 4% hydroquinone, left overnight. Morning ectoine went only to the cysteamine group; the comparator used placebo cream. Everyone received SPF 30 sunscreen.¹

Unequal morning products prevent isolating cysteamine’s contribution.¹

Ask whether the proposed routine matches what was studied, including the moisturizer and morning products. If the answer is no, ask which evidence supports the version you have been offered.

How far the result goes

By day 56, average mMASI pigmentation scores fell from 5.45 to 3.81 versus 5.46 to 4.01. The reported between-group P=.67 does not establish equivalence; the paper supplies no noninferiority margin or confidence interval for that comparison.¹

The researchers did not assess side effects. The eight-week experiment therefore cannot establish overnight tolerability or longer-term safety.¹

Keep the safety question beside the pigmentation question. Before starting, ask what burning, redness or other reaction should prompt stopping and contacting the clinician, and when the first review will happen. A treatment plan should identify what you will measure and who will review it.

Your product’s contact time still matters

For example, the manufacturer’s current page describes Cyspera² Intensive as a 7% cysteamine rinse-off cream, starting at five minutes and increasing to fifteen.² That is a different concentration and schedule from the experiment.

Use the name and instructions on your own product when discussing contact time. Avoid substituting a study’s overnight routine for a rinse-off direction without a clinician reviewing the particular formulation.

The AAD recommends gentle, fragrance-free skin care for melasma and warns that a product that burns or stings can irritate skin and darken spots.³ Bring photos of everything you currently apply, including products bought online or abroad, so the clinician can review the whole routine.

Keep sun protection in the plan

The AAD advises broad-spectrum, water-resistant SPF 30 or higher, shade and a wide-brimmed hat. It also recommends tinted sunscreen containing iron oxide for protection from visible light, which can worsen melasma.³

If hydroquinone is being considered in the US, FDA⁴ says hydroquinone skin-lightening products are not approved for over-the-counter sale; prescription products are available through a healthcare provider.⁴ Discuss the actual prescribed formulation and follow-up rather than ordering an unapproved OTC lightener.

Skin, Head to Toe includes “What to Say at the Appointment,” with prompts to bring your product history and photographs, describe the effect on daily life, and mention pregnancy plans. Use it to prepare the treatment conversation. See the book.