Sunscreen and Melasma: The Part Everyone Underestimates
中文摘要在文末
I want to start with the sentence that changes how most of my melasma patients think about this.
Sunscreen is not there to stop you getting sunburnt. For melasma, sunscreen is the treatment.
Not the supporting act, not the thing you add on top of the "real" medication. If you get everything else right and this wrong, you will spend years going in circles. I've watched it happen often enough that I now spend more consultation time on sunscreen than on any prescription I write.
Here's why.
The thing almost nobody in Malaysia knows
Ask most people what sunscreen protects against and they'll say the sun, or UV, or maybe UVA and UVB if they've read the label carefully.
That's two-thirds of the answer.
Sunscreen for pigmentation needs to cover two types of UV, and also visible light — which is exactly what it sounds like: ordinary light that you can see. Daylight through a window. Light bouncing off a pale wall or a wet road. The general brightness of being outdoors on an overcast day.
Visible light drives melasma. And because virtually nobody here knows that, virtually nobody is protecting against it — which, in my view, is a large part of why melasma recurrence rates in Malaysia are as high as they are. People do everything else right, use a perfectly decent SPF 50, stay out of direct sun, and still watch their pigmentation creep back, and nobody can tell them why.
This is the hidden piece. And once you know about it, a lot of confusing things start making sense — like why your melasma seems to darken in months when you were barely outdoors, or why it never quite settles despite religious sunscreen use.
What to actually look for
Three things, together. All three, not two out of three.
SPF 50+ — this covers UVB, the sunburn wavelength. This is the number everyone already knows and the one people over-focus on.
PA++++ — this is the UVA rating, and UVA is the one that penetrates deeper and contributes heavily to pigmentation and ageing. Four plus signs is the highest rating. Plenty of products with a high SPF have mediocre UVA protection, so check for this separately rather than assuming a big SPF number covers it.
Iron oxide — this is the visible light one, and it's the ingredient most people have never heard of. Iron oxides physically block visible light, and they're what makes a sunscreen tinted rather than clear. This matters: a completely clear, invisible sunscreen almost certainly isn't protecting you against visible light. If you specifically sought out a sunscreen that leaves no colour at all, you may have optimised for the wrong thing.
The one I use in the clinic is Derm Eden DD Cream, chosen for exactly those three reasons — SPF 50+, PA++++, and iron oxide in the formulation. There are others that meet the criteria. What I'd rather you take from this is the checklist, so you can assess anything you're offered rather than depending on any single product.
My rule, and why it's deliberately blunt
Here's something I've learned from years of giving instructions to patients, and it applies well beyond sunscreen:
The more choices I give someone, the worse the decision they make.
Suppose I say: "Reapply every four to six hours, or more frequently if you're outdoors, depending on how much you're sweating and how strong the sun is." That sounds thorough. It sounds like good, individualised advice.
What actually happens is that you go home, and every application becomes a small negotiation. Is this four hours or five? Is walking to the car "outdoors"? It's cloudy today, does that count? And the interpretation always drifts in the same direction — towards less. The practical outcome is once a day, or none at all.
So I stopped doing that. My rule for melasma patients is:
At least twice a day, every day — even if you are indoors the whole day.Every two to three hours if you're going to be in direct sunlight.
That's the entire rule. No conditions to weigh up, no judgement calls.
And yes, I genuinely mean twice a day even if you never leave the office. Windows transmit plenty of what we're trying to block. Indoor lighting contributes. And more importantly, "indoors all day" almost never survives contact with reality — there's the walk to the car, the trip downstairs, the errand at lunch. If your baseline is twice daily regardless, those moments are covered.
I'd rather give you a simple rule you'll follow than a precise one you'll abandon by week three.
The application mistakes
Three, and they're all common.
Not using enough. This one is nearly universal. There's a two-finger guide for the face — the amount squeezed along the length of your index and middle fingers. That's considerably more than the small dab most people are using, and if you're using less, your actual protection is a fraction of what's on the label. The label figure is measured at a specific application thickness. Use half of it and you don't get half the protection; you get considerably less than half.
Cutting back once it improves, because it feels wasteful to keep using so much when the skin looks better. I understand the instinct — the product is expensive and the problem seems solved. But the improvement is the sunscreen working.Reducing it at that point is precisely how you lose the ground you spent months gaining. This is one of the most self-defeating things I see, and it's always done with good intentions.
Not reapplying. Morning application only, then nothing for the next ten hours. Sunscreen degrades, sweats off, gets rubbed off. In this climate, especially so. That's the whole reason my rule has a second application in it — not because the morning one was wrong, but because by afternoon it isn't really there anymore.
Why melasma punishes lapses so quickly
I want to be honest about how responsive this is, because it surprises people.
With eczema, if you're slack for a week, you'll often get away with it. Melasma isn't like that. If a patient misses sunscreen a few times and gets some direct sun, I can frequently see the darkening at the next visit. Not months later. Next visit.
The pigment cells don't need much encouragement to resume what they were doing. They've been doing it for years — that's how the melasma formed in the first place — and treatment is suppressing an active process rather than removing a finished deposit.
Which is why melasma maintenance demands more discipline than most conditions I manage. I say this not to frighten anyone, but because patients who understand it early do markedly better than those who spend a year hoping there's a version of this where the sunscreen becomes optional.
Making it actually happen
The practical problem isn't knowledge, it's habit. A few things that help:
Attach it to something you already do without thinking. After brushing your teeth in the morning. After lunch. The second application is the one that fails, so give it a fixed anchor rather than relying on remembering.
Keep the second one where you'll be. In the office drawer, in your bag, at your desk. A tube sitting at home is a tube that doesn't get used at two in the afternoon.
Tinted is a feature, not a compromise. Many patients are pleased to discover a tinted sunscreen evens out how the pigmentation looks while they're wearing it. That's cosmetic rather than treatment — but if it makes you more likely to apply it consistently, it's doing real work.
Don't stack it under something that removes it. If you're rubbing on other products over the top, apply the sunscreen last and let it settle.
The short version
Melasma treatment is sun protection plus topical medication, and of those two, the one people underestimate is the sunscreen.
Look for SPF 50+, PA++++, and iron oxide together. Use two fingers' worth on your face. At least twice a day, every day, indoors or not. Every two to three hours in direct sun. Don't reduce it when things improve.
Do that consistently and the medications get a chance to work. Skip it and you'll be treating against a process that's being re-triggered daily — which is a slow, expensive, and demoralising way to go about it.
If you want help choosing something suitable for your skin, or working out why your current routine isn't holding, come and see me. Klinik Dr Tan (Skin & Acne), Lot 27, Ground Floor, Block D, Lintas Square, Kota Kinabalu. WhatsApp 017-234 7328. Appointments preferred.
I'm a GP with a strong interest in skin, not a dermatologist.
Book a consultation with Dr. Tan — Book Online or WhatsApp 017-234 7328.
简要说明
我是陈医生，亚庇 Lintas Square 的 Klinik Dr Tan（皮肤与暗疮）。我是对皮肤有专长的普通科医生，不是皮肤专科医生。
对黄褐斑来说，防晒不是辅助，防晒就是治疗本身。
多数人以为防晒只防紫外线。其实需要防的是两种紫外线，再加上可见光——就是你眼睛看得到的普通光线：窗户透进来的日光、墙面反射的光、阴天户外的亮度。
可见光会加重黄褐斑。这一点在马来西亚几乎没有人知道，我认为这正是本地复发率偏高的隐藏原因。很多人其他都做对了，仍然反反复复，却找不出原因。
选防晒看三样，缺一不可：
SPF 50+（防 UVB）
PA++++（防 UVA，四个加号是最高级别；SPF 高不代表 UVA 防护好，要分开看）
氧化铁（iron oxide）——这是防可见光的关键成分，也是防晒有颜色（tinted）的原因。完全无色透明的防晒，通常代表没有可见光防护。
诊所使用的是 Derm Eden DD Cream，正是因为符合这三项。重点是记住这个清单，你就能自己判断任何产品。
我的规则（故意订得很简单）：
每天至少两次，即使整天待在室内。 会晒到太阳的话，每两到三小时补一次。
规则给得越复杂，执行率越低。如果我说「四到六小时一次，视情况而定」，结果往往是一天一次或者干脆不擦。
三个常见的涂抹错误：
用量太少。脸部用「两指法」——食指加中指长度的量。用一半的量，防护力远低于一半。
好转后减量，觉得「浪费」。但好转正是防晒在起作用，这时减量等于把几个月的成果还回去。
不补涂。早上擦一次，之后十小时都没有了，在我们这种气候尤其如此。
黄褐斑对疏忽的反应很快：防晒断了几次又晒到太阳，下次复诊我通常就看得出变深了。它的维持比湿疹更需要纪律。
帮助养成习惯：把它绑在既有习惯上（刷牙后、午餐后）；第二支放在办公室或包包里；有颜色的防晒能同时修饰肤色，反而让人更愿意用。
Klinik Dr Tan (Skin & Acne)，Lot 27, Ground Floor, Block D, Lintas Square, Kota Kinabalu。WhatsApp：017-234 7328。建议预约。
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