If your melasma seems to fade a little over winter and then returns almost exactly where it was the moment summer arrives, you are not imagining the pattern, and understanding what causes melasma is the key to finally breaking that cycle. Melasma is not a simple, single-trigger condition like an ordinary sunspot. It is a chronic, relapsing pigmentation disorder driven by a combination of forces working together beneath the surface, which is exactly why it responds so unpredictably to generic skincare and keeps resurfacing even after it appears to have cleared. This guide explains what is actually happening in your skin, which triggers matter most, and why understanding the "why" is the real first step toward managing it long term, whether you're in Markham or anywhere else dealing with this frustrating pattern.
TL;DR: Key Takeaways
Melasma is caused by a combination of genetics, UV and visible-light exposure, and hormones, not one single trigger.
Sun exposure is the leading precipitating factor, identified in up to 96% of cases in clinical studies.
Melasma is significantly more common in women and in people with darker skin tones (Fitzpatrick III to VI).
Hormonal changes (pregnancy, birth control, hormone therapy) are a major reason melasma often first appears or worsens.
Even brief, incidental sun or visible-light exposure can reactivate melasma in predisposed skin.
Because melasma is chronic and relapsing, understanding your personal triggers matters more than any single product.
Book a complimentary consultation at Beyond Medical Aesthetics, Markham.
Table of Contents
• What Is Happening in the Skin When Melasma Develops?
• Is Sun Exposure Really the Biggest Trigger for Melasma?
• Why Do Hormones Play Such a Large Role in Melasma?
• Who Is Most Likely to Develop Melasma, and Why?
• Why Does Melasma Keep Relapsing Even After It Seems to Clear?
• How Is Melasma Different From Ordinary Sun Spots or Hyperpigmentation?
• Conclusion: Understanding Your Triggers Is the First Step
• Frequently Asked Questions
What Is Happening in the Skin When Melasma Develops?
Melasma occurs when melanocytes, the cells in your skin responsible for producing pigment, become overactive in specific areas, typically the cheeks, forehead, upper lip, and chin, producing symmetrical brown or grey-brown patches. Unlike a sunspot, which is usually a localised, single-cause reaction, melasma involves a more complex process beneath the surface that current research links to genetic susceptibility, ultraviolet and visible-light exposure, hormonal influences, and in some cases cosmetics or certain medications acting together.
This multifactorial nature is precisely why melasma cannot be reliably explained by "too much sun" alone, and why two people with seemingly similar sun exposure can have very different experiences with it. One may never develop melasma, while another with a genetic predisposition develops it after a single intense hormonal or sun-exposure event.
Is Sun Exposure Really the Biggest Trigger for Melasma?
Yes, and by a significant margin. A retrospective clinical study of melasma patientsidentified sun exposure as the leading precipitating factor in 96.3% of cases, making it, by a wide margin, the single most consistently documented trigger across studies.
What surprises many people is how little exposure is actually needed to reactivate melasma in predisposed skin. A short walk without sunscreen, sitting near a sunlit window, or driving with the sun coming through the windshield can all be enough. Research has also shown that visible light, not just UV radiation, can trigger melanocyte activity, which is why standard UV-only sunscreens are increasingly considered insufficient for melasma-prone skin, and why physical, iron-oxide-containing formulas are now more frequently recommended.
This explains the seasonal pattern so many people notice: melasma often appears to improve over winter months with less sun exposure, only to resurface again as UV and visible-light exposure increase, a pattern our Markham clients often describe clearly once they understand what's actually driving it.
Why Do Hormones Play Such a Large Role in Melasma?
Hormonal influence is the second major factor,identified in roughly half of melasma casesin the same clinical research, and it explains why melasma so often appears at specific life stages.
Melasma is frequently called the "mask of pregnancy" because pregnancy-related hormonal shifts are one of the most common triggers for its first appearance. It also commonly develops or worsens with hormonal birth control and hormone replacement therapy. The exact mechanism is still being studied, but oestrogen and progesterone are understood to influence melanocyte activity, which is why melasma can appear, worsen, or occasionally improve alongside hormonal changes throughout a person's life.
This is also why melasma that appeared during pregnancy sometimes fades significantly after childbirth, while for others it persists and requires active management: the hormonal picture is genuinely individual.
Wondering whether your own melasma pattern points to sun, hormones, or both? Book a complimentary consultation at Beyond Medical Aesthetics in Markham and our team will help you understand your specific triggers before recommending a plan.
Who Is Most Likely to Develop Melasma, and Why?
Melasma is significantly more common in women than men, and far more common in people with darker skin tones, particularly Fitzpatrick skin types III through VI, which naturally produce more melanin. Worldwide prevalence estimates vary enormously, from roughly 1% to as high as 41%, largely because rates differ dramatically across ethnic groups and geographic regions with different levels of ambient UV exposure.
Genetics also play a clear role: a family history of melasma is a recognised risk factor, suggesting an inherited predisposition in how certain people's melanocytes respond to UV, visible light, and hormonal signals. This is why some people can spend years in high-sun environments without ever developing melasma, while others develop it after comparatively limited exposure.
Why Does Melasma Keep Relapsing Even After It Seems to Clear?
This is the question that frustrates people more than any other, and the answer comes back to the multifactorial nature of the condition itself.
Because melasma is driven by an underlying predisposition rather than a single external cause, the melanocytes involved remain primed to reactivate whenever a trigger reappears (sun exposure, hormonal shifts, or even certain inflammatory skin reactions). Treating the visible pigment without addressing ongoing triggers, particularly UV and visible-light exposure, is one of the most common reasons melasma appears to respond to treatment initially and then returns within weeks or months.
This is also why melasma is now understood clinically as a chronic, relapsing condition to be managed on an ongoing basis, rather than a problem with a single, permanent fix: a distinction that changes how both prevention and treatment should be approached.
How Is Melasma Different From Ordinary Sun Spots or Hyperpigmentation?
General hyperpigmentation, such as sun spots or marks left behind from acne, tends to be a more localised, single-cause reaction that responds fairly predictably to brightening ingredients. Melasma is a distinct, chronic condition with a more complex hormonal and vascular component beneath the surface, which is why it often does not respond the same way to the same treatments, and why treatments that are too aggressive can sometimes worsen melasma by triggering inflammation.
Because the two conditions look similar but behave very differently, an accurate diagnosis is an important first step before choosing a treatment approach. Our melasma treatment page outlines the specific, melasma-safe treatment protocols we use once your triggers and skin have been properly assessed, and our pigmentation and spots page covers non-melasma hyperpigmentation if that is a better fit for what you are seeing.
Conclusion: Understanding Your Triggers Is the First Step
Melasma is not caused by one thing, and it will not be solved by treating one thing. It develops from a combination of genetic predisposition, UV and visible-light exposure, and hormonal influence working together, which is exactly why understanding your own specific triggers, rather than following generic skincare advice, is the real foundation of managing it successfully over the long term.
At Beyond Medical Aesthetics in Markham, our registered-nurse-led team takes the time to understand your individual melasma triggers and history before recommending a treatment plan, because a plan that ignores your specific triggers is a plan that is likely to see the pigmentation return.
Frequently Asked Questions
Can melasma be caused by stress?
While UV exposure and hormones are the most strongly documented triggers, chronic stress can influence hormone levels in ways that may contribute to melasma flares in predisposed individuals. It is not considered a primary trigger on its own, but managing stress alongside sun protection and hormonal factors is a reasonable part of an overall approach.
Does melasma run in families?
Yes, a family history of melasma is a recognised risk factor, suggesting a genetic predisposition in how certain people's skin responds to UV exposure, visible light, and hormonal changes. If a parent or sibling has experienced melasma, your individual risk is higher, particularly with significant sun exposure or hormonal changes.
Why did my melasma appear during pregnancy but not before?
Pregnancy causes significant hormonal shifts, particularly in oestrogen and progesterone, which are understood to influence melanocyte activity in genetically predisposed individuals. This is why melasma is commonly called the "mask of pregnancy" and frequently first appears or worsens during this time, even in people who previously had no pigmentation concerns.
Can birth control cause melasma to come back?
Yes. Hormonal contraceptives are a recognised trigger for melasma, since they alter hormone levels in ways similar to pregnancy. If melasma returns or worsens after starting or changing a hormonal birth control method, that timing is a meaningful clue worth discussing with your provider.
If I stay out of the sun completely, will my melasma go away?
Strict, consistent photoprotection significantly reduces melasma flares and is considered the essential foundation of any management plan, but because melasma also involves genetic and hormonal factors, sun avoidance alone does not always fully resolve existing pigmentation. Most effective plans combine rigorous photoprotection with targeted treatment addressing the pigmentation already present.