SkincareSafety Guide

Skin

Understand your skin type, tone, and what your skin is doing.

View all skin guides

Start here

Skin typesThe main skin types and how they differ.Find your skin typeA practical identification guide.What different skin types look likeVisual differences between common skin types.

Common skin questions

Oily skinWhat oily skin means and how to read it.Skin type changesHow skin type can shift over time.Skin type and ageHow visible aging differs by skin type.
Not sure where to start?Use the skin-type guide before choosing routines or ingredients.

Concerns

Start from a skin problem or visible change.

View concern guides

Oil and acne

Why oily skin happensThe main drivers behind excess oil.Oily skin and acneHow oil can contribute to breakouts.Can oily skin cause acne?A direct answer to the oil-acne link.

Changes and warning signs

Stress and oily skinHow stress may affect oiliness.Dehydration and oilinessWhy skin can feel oily and dehydrated.Skin cancer signsVisual signs that need professional attention.
Looking for a solution?Start with what oily skin actually needs before adding stronger products.

Ingredients

Understand what ingredients do and whether they fit your skin.

View ingredient questions

Explore ingredients

NiacinamideA practical ingredient overview.Vitamin C serumWho can use vitamin C and when to be careful.RetinolHow retinol fits different skin types.

Use safely

Salicylic acidWhere this acne-focused ingredient fits.Niacinamide for all skin typesSuitability across skin types.Ingredient comparisonsUse comparisons to avoid mismatched decisions.
Can my skin use this?Browse compatibility questions before adding a new active.

Routines

Turn skin information into daily decisions.

View routine questions

Daily basics

Does every skin type need moisturizer?A basic routine decision.Does every skin type need sunscreen?Where SPF fits in daily care.What oily skin needsA simple care direction for oily skin.

Adjust over time

Skin changes with ageWhen your routine may need to change.Seasonal skin changesHow weather affects skin behavior.Korean skincare approachWhat is useful beneath the trend.
Starting from scratch?Begin with moisturizer, sunscreen, and one skin-specific need.

Products

A small selection of skincare products recommended by OuterDerm for simple, effective everyday routines.

View all products

Recommended picks

Daily SunscreenDaily UV protection that has to be wearable enough to stick with.Azelaic AcidA focused 10% azelaic acid when uneven tone or blemish marks are the concern.Gentle CleanserComfortable cleansing when tight or squeaky skin is a warning sign.
Not sure where to start?Browse three carefully selected essentials, then ask on WhatsApp before you order.

Learn

Go deeper into skin science, myths, evidence, and safety.

View learning guides

Hazardous ingredients

Safety hubStart with mercury, steroids, PPD and other hazardous substances.Ingredient safety indexBrowse Phase 1 and Phase 2 hazardous ingredients.Mercury in whitening creamsLabel names, Punjab alerts, and what to do now.

Product literacy

Product literacy hubHow to read labels, claims, and INCI lists before you buy.How to read an ingredient labelINCI order, Parfum, and missing-list red flags.Fragrance-free vs unscentedHow to verify a fragrance-free claim on the ingredient list.How to choose sunscreenBroad spectrum, wearability, and a readable pack — not a fairness claim.

Skin science

Skin color geneticsHow inherited traits shape skin color.Skin color typesHow skin tone is commonly grouped.Are skin types genetic?What genetics can and cannot explain.

Evidence and myths

Can all skin types tan?Tanning, risk, and skin type.Is oily skin good or bad?A balanced view of oily skin.Why Korean skin looks flawlessTrend claims translated into practical basics.
Want the evidence layer?Use why-guides when you want causes, mechanisms, and context.

Skin Conditions

What Causes Melasma?

Melasma is a condition with a clear set of causes. It's not random; it's the result of a predictable interaction between the environment and your skin.

Quick answerMelasma is caused by three primary factors: exposure to UV radiation from the sun or other sources, hormonal changes (particularly fluctuations in estrogen and progesterone), and a genetic predisposition.

Medically reviewed by Dermatology reviewer · Updated Jul 19, 2026 · 6 min read

A close-up of a melasma patch on the skin, illustrating the causes
Cause 1UV Exposure
Cause 2Hormonal Changes
Cause 3Genetics
The InteractionThese causes work together
The MechanismOverproduction of melanin

Key answer

Well-established

Melasma is caused by the interaction of three factors: UV exposure, hormonal changes, and genetics. This understanding is the foundation for any effective management strategy.

Evidence
Strong - Well-established
Best for
Anyone looking for a clear, definitive answer to what causes melasma; People wanting to understand the science behind their pigmentation

See what the evidence shows

Short version

Story in brief

Melasma is caused by the interaction of three key factors. Each one is a necessary part of the puzzle, and together they create the condition. The first cause is UV radiation, which directly signals the skin to produce more pigment.

The second cause is hormones, especially estrogen and progesterone. These hormones make the pigment cells more sensitive and reactive. The third cause is genetics, which determines the underlying sensitivity of your pigment cells. You need all three factors to have melasma.

This explains why melasma is so common in certain situations: a woman with a family history of melasma who becomes pregnant and spends time in the sun is the classic example of all three causes lining up.

Mental model

Visual explanation

Evidence

What the evidence shows

The causes of melasma are not a matter of one bad habit or one random event. It's a combination of factors that work together. This is why a multi-faceted approach is needed to address it.

Use this section to decide

Does this advice apply to me?

Find the concern or goal closest to yours, then use the fit signal to decide how much weight to give this guide.
Strong fit means the advice is central to that goal.Depends means formula, tolerance, or context matters more.Use caution means do not treat it as the main answer.

  • If your goal is

    Cause 1Depends
    Fit signal
    Possible fit

    UV Exposure

  • If your goal is

    Cause 2Depends
    Fit signal
    Possible fit

    Hormonal Changes

  • If your goal is

    Cause 3Use caution
    Fit signal
    Limited evidence

    Genetics

  • If your goal is

    The ResultUse caution
    Fit signal
    Limited evidence

    Melasma

Research notes already in this guide

  • The link between melasma and UV exposure is one of the most consistently demonstrated relationships in dermatology.
  • The high prevalence of melasma in women during pregnancy or with oral contraceptive use provides robust evidence for the hormonal cause.
  • Family history is a well-documented risk factor, confirming the genetic cause.
  • The condition is more prevalent and persistent in individuals with darker skin, which is also linked to genetics.

Explanation

How it works

  1. The UV Signal

    UV radiation from the sun provides the initial stimulus to the melanocytes.

  2. The Hormonal Amplifier

    Hormones make the melanocytes more sensitive, amplifying the signal from the UV.

  3. The Genetic Predisposition

    Genetics determine the baseline sensitivity of the melanocytes, which sets the threshold for activation.

  4. The Result: Melasma

    The combination of all three causes leads to the overproduction and deposition of melanin.

Practical use

How to use it

  1. Address the UV Cause

    Use daily high-SPF sunscreen to minimize the UV stimulus. This is the most important step.

  2. Address the Hormonal Cause

    If you are on hormonal medications, discuss the possibility of alternatives with your doctor.

  3. Address the Pigment

    Work with a dermatologist to use treatments that can help fade the pigment that has already formed.

Safety

Side effects and cautions

  • Thinking it's caused by a single factor (like just sun)

    Melasma is rarely caused by just one thing. It's almost always a combination of factors.

  • Believing it's a cause of a vitamin deficiency

    Melasma is not caused by a nutritional deficiency. It's a condition of pigment overproduction.

  • Assuming it's a sign of an allergy

    Melasma is not an allergic reaction. It's a pigmentation issue caused by a combination of factors.

Worth noting

Small details that can change the answer

  • UV is the Primary Cause. UV radiation is the most significant environmental cause of melasma.
  • Hormones Are a Key Cause. For most women, hormonal fluctuations are a critical cause of their melasma.
  • Genetics Set the Stage. Your genetics are the foundation upon which the other causes act.
  • It's a Multi-Causal Condition. Melasma is not caused by one thing, but by the interplay of multiple factors.

Melasma is caused by a combination of UV, hormones, and genetics.

UV radiation is the primary environmental cause.

Hormonal changes are a key cause, especially for women.

Genetics determine your susceptibility to the other causes.

A multi-faceted approach is needed to address all the causes.

Definition

Defining the Causes of Melasma

Melasma is a multi-causal condition, meaning its development is driven by a combination of factors. The three primary causes are: (1) UV radiation from the sun, (2) hormonal changes, particularly with estrogen and progesterone, and (3) a genetic predisposition. The causes do not operate in isolation; they interact to produce the condition.

Explanation

Understanding the Three Causes

UV radiation is the primary environmental cause. It directly stimulates the pigment-producing cells. Hormonal changes are the primary internal cause. They make the pigment cells more sensitive to the UV signal. Genetics are the backdrop; they determine the inherent sensitivity of the pigment cells and whether a person is predisposed to melasma. All three causes need to be present to some degree for melasma to develop.

Questions

Frequently asked questions

What is the most common cause of melasma?

The most common cause is the combination of UV exposure and hormonal changes in women.

Can stress cause melasma?

Stress is not a direct cause, but it can affect hormone levels, which are a cause.

Can certain foods cause melasma?

No, diet is not a known cause of melasma.

Does makeup cause melasma?

No, makeup itself is not a cause. However, some ingredients may cause irritation, which is a separate issue.

References

Sources

The notes below are drawn from the evidence already cited in this guide. They are not a complete bibliography.

  1. The link between melasma and UV exposure is one of the most consistently demonstrated relationships in dermatology.
  2. The high prevalence of melasma in women during pregnancy or with oral contraceptive use provides robust evidence for the hormonal cause.
  3. Family history is a well-documented risk factor, confirming the genetic cause.
  4. The condition is more prevalent and persistent in individuals with darker skin, which is also linked to genetics.