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 Concerns & Causes

Why Do I Have Hyperpigmentation?

Hyperpigmentation is one of the most common skin concerns, but the reasons behind it vary widely. Understanding your cause is the first step to treating it.

You look in the mirror and there they are - dark spots that weren't there before. And you have no idea why.

Hyperpigmentation isn't a single condition with a single cause. It's a symptom, and there are several common reasons it shows up.

So why do you have hyperpigmentation?

Hyperpigmentation is like an alarm system for your skin - it's telling you that something has happened or is happening beneath the surface.

Quick answerYou have hyperpigmentation because your melanocytes (pigment-producing cells) have produced excess melanin in response to a trigger.

Medically reviewed by Skin Editorial Team · Updated Jul 18, 2026 · 4 min read

Hyperpigmentation causes shown on skin with labels
Primary CauseSun exposure triggers melanin
Second CauseInflammation (acne, injury)
Third CauseHormonal changes
Other CausesMedications, genetics
Key PointMelanin overproduction is the common thread

Key answer

Multiple possible causes

Your hyperpigmentation is caused by one of five main triggers - sun exposure, inflammation, hormones, medications, or genetics. Identifying yours is key to effective treatment.

Evidence
Strong - Multiple possible causes
Best for
Anyone trying to understand their hyperpigmentation
Limitation
Those needing a single simple answer

See what the evidence shows

Short version

Story in brief

Melanin is the pigment that gives skin its color, produced by cells called melanocytes. Hyperpigmentation happens when these cells go into overdrive, producing more melanin than usual in a specific area. This overproduction is triggered by something.

The most common trigger is UV exposure - it's the skin's protective response, like a biological umbrella trying to shield deeper tissues from damage. Inflammation is another major trigger: any injury, from acne to a cut, can leave behind pigment as part of the healing process.

Hormones are a powerful driver of pigmentation, particularly during pregnancy or with hormonal medications. Genetic factors also play a role, with certain skin types more prone to pigmentation than others. And some medications, photosensitizing drugs, can trigger pigmentation as a side effect.

Mental model

Visual explanation

Evidence

What the evidence shows

Hyperpigmentation is always a response to something - it doesn't happen randomly. The cause might be obvious (like a sunburn) or hidden (like a hormonal change), but there's always a trigger.

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

    Sun exposureDepends
    Fit signal
    Possible fit

    Most common cause

  • If your goal is

    InflammationUse caution
    Fit signal
    Limited evidence

    Acne, injury, conditions

  • If your goal is

    HormonesUse caution
    Fit signal
    Limited evidence

    Pregnancy, birth control

  • If your goal is

    MedicationsUse caution
    Fit signal
    Limited evidence

    Some drugs trigger it

Research notes already in this guide

  • Fitzpatrick skin types III-VI are more prone to pigmentation disorders.
  • Unprotected sun exposure significantly increases risk of all types.
  • Hormonal changes (pregnancy, birth control) are a major risk factor for melasma.
  • Skin trauma (acne, procedures, injuries) often leads to PIH.

Explanation

How it works

  1. Trigger activates melanocytes

    UV, inflammation, hormones, or medications stimulate pigment-producing cells.

  2. Melanin production increases

    Melanocytes produce more melanin than usual in the affected area.

  3. Pigment accumulates

    The excess melanin is distributed to skin cells, causing visible darkening.

  4. Pigmentation appears

    The dark spot appears on the skin's surface.

Practical use

How to use it

  1. Identify your trigger

    Think about when and where your pigmentation started - sun, inflammation, hormones, or medications?

  2. Remove or manage the trigger

    Sun protection, manage acne, discuss medications with your doctor.

  3. Treat the pigmentation

    Use brightening agents appropriate for your skin type.

Safety

Side effects and cautions

  • Assuming all hyperpigmentation is sun damage

    Could be inflammation, hormones, or medications - investigate the source.

  • Treating hyperpigmentation without addressing the cause

    Identifying and addressing the trigger is essential for effective treatment.

  • Ignoring ongoing triggers

    If you're still getting sun exposure or new breakouts, pigmentation will continue.

Fit

Who should be careful

  • Those needing a single simple answer

Worth noting

Small details that can change the answer

  • Melanocytes. These cells produce melanin - they're the source of all pigmentation.
  • UV Trigger. Sun exposure is the most common cause of hyperpigmentation.
  • Inflammation Trigger. Any injury or inflammation can trigger a pigment response.
  • Hormonal Trigger. Estrogen and progesterone can stimulate melanin production.

Hyperpigmentation is caused by excess melanin production in response to triggers.

The most common triggers are sun exposure, inflammation, hormones, medications, and genetics.

Identifying your specific cause helps guide treatment.

Managing triggers is as important as treating existing spots.

Different causes require different treatment approaches.

Explanation

The 5 main causes explained

Here are the most common causes of hyperpigmentation.

Benefits

Identifying your cause

Understanding your specific cause helps you choose the right treatment.

  • Sun damage: Irregular spots in sun-exposed areas
  • Post-inflammatory: Spots where you've had acne, cuts, or irritation
  • Melasma: Symmetrical patches on the face, often hormone-related
  • Medication-related: May appear shortly after starting a new medication
  • Genetic: Freckles and certain birthmarks

Questions

Frequently asked questions

Can stress cause hyperpigmentation?

Indirectly - stress can worsen conditions like acne or eczema, which can then cause PIH.

Why do I have hyperpigmentation on my face only?

The face is often the most sun-exposed area and prone to hormonal changes.

Is hyperpigmentation genetic?

Yes - certain skin types are more prone to pigmentation disorders.

Can skin infections cause hyperpigmentation?

Yes - any skin inflammation or infection can lead to post-inflammatory pigmentation.

References

Sources

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

  1. Fitzpatrick skin types III-VI are more prone to pigmentation disorders.
  2. Unprotected sun exposure significantly increases risk of all types.
  3. Hormonal changes (pregnancy, birth control) are a major risk factor for melasma.
  4. Skin trauma (acne, procedures, injuries) often leads to PIH.