Dark marks after spots (post-inflammatory hyperpigmentation)

What it is

Post-inflammatory hyperpigmentation (PIH) is a flat brown, grey or black mark that appears where skin was inflamed or injured. It is not a scar: the skin surface is smooth, but extra pigment has been deposited. Marks in the top layer of skin are brown and fade over months; deeper marks look grey-blue and can take a year or longer.

How it works

Any inflammation — a pimple, a bite, eczema, a burn or a harsh product — releases chemical signals that switch melanocytes (the pigment cells) into overdrive. They make extra melanin and pass it to surrounding skin cells, and sometimes melanin drops into the deeper dermis, where it lingers far longer. Marks in the top layer (epidermal) look brown and fade over months; deeper (dermal) marks look grey-blue and can take a year or more.

Why it matters on darker skin

Melanocytes in darker skin are more reactive. Any inflammation, from a pimple to a scratch, signals them to make extra melanin. That is why PIH is one of the most common reasons people of African descent see a dermatologist, and why the mark often bothers people more than the spot that caused it.

Causes and triggers

Acne is the most common trigger, followed by eczema, insect bites, ingrown hairs, razor bumps, burns, waxing, harsh scrubs and reactions to products. Sun exposure and visible light darken existing marks. Picking and squeezing deepen inflammation and push pigment lower.

What helps — and why it works

Treat the cause first: controlling acne or eczema stops new marks forming. Daily broad-spectrum SPF 30+ sunscreen, ideally a tinted one with iron oxides, stops marks darkening in sunlight and visible light. Gentle ingredients with evidence for fading include azelaic acid, niacinamide, vitamin C and retinoids; a doctor may suggest prescription options. Be patient: improvement is measured in months. Treat the cause first: no new inflammation means no new marks; controlling acne or eczema is the single biggest step. Expected timeline: new marks stop within 4–8 weeks of control. Daily broad-spectrum SPF 30+, ideally tinted with iron oxides: UV and visible light stimulate melanocytes; tinted mineral sunscreens also block visible light, which matters more in darker skin. Expected timeline: protects from day one; makes every other treatment work. Azelaic acid, niacinamide or adapalene: azelaic acid calms overactive melanocytes, niacinamide blocks pigment transfer to skin cells, adapalene speeds skin renewal. Expected timeline: visible change in 8–12 weeks; full effect 3–6 months. Be patient and consistent: skin renews roughly every 4–6 weeks, so pigment leaves in waves. Expected timeline: most epidermal marks fade over 3–12 months.

What to avoid and why

Do not pick or squeeze spots. Avoid harsh scrubs, lemon juice, toothpaste and "fast-acting" toning creams, which inflame the skin and create more marks. Never use unlabelled creams or creams containing mercury or strong steroids.

Common mistakes

• Scrubbing marks with lemon, lime, toothpaste or hard exfoliants — this creates more inflammation and more marks.
• Buying 'fade' creams of unknown origin, which may contain mercury, steroids or high-strength hydroquinone.
• Stopping sunscreen once marks start fading, so they darken again.
• Using many actives at once, which irritates and backfires.

Building a routine that lasts

Most skin problems improve with a short routine used every day rather than many products used occasionally. A practical base is a gentle cleanser, a fragrance-free moisturiser and a broad-spectrum sunscreen in the morning, with one targeted treatment at night. Introduce one new product at a time and give it two weeks before adding another, so that if your skin reacts you know the cause. Patch-test on the inner arm or behind the ear for a few days first. Skin renews itself roughly every four to six weeks, so most treatments need two to three cycles — eight to twelve weeks — before you can judge them fairly. Photographs taken in the same light every four weeks are more reliable than memory. In the Nigerian climate, heat, humidity and harmattan all change what your skin needs: lighter gels in the humid season and richer creams in dry months are both reasonable. If a product stings for more than a few minutes, causes swelling, or leaves new dark patches, stop it. Buy from registered pharmacies or official stockists, and use the Authenticity Check if you are unsure whether a product is genuine.

Reading labels and choosing products

On the label, look first for the active ingredient and whether the product is fragrance-free and non-comedogenic. Ingredients are listed in order of amount, so an active at the end of a long list may be present only in a small quantity. Be wary of products that promise results in days, that list no ingredients, or whose label is a sticker or handwritten. Words such as 'natural', 'herbal', 'organic' and 'dermatologist-inspired' are marketing terms, not safety standards. Hydroquinone, mercury compounds (sometimes listed as calomel or mercurous chloride) and strong steroids such as clobetasol do not belong in an over-the-counter cosmetic. A real NAFDAC registration number should be printed on the pack and should match the product on the official Greenbook register. Price is not proof: counterfeiters copy expensive brands. When in doubt, ask a pharmacist, keep your receipt, and use Melanin & Me's Authenticity Check and barcode scanner as a first screen.

Questions to ask your doctor or pharmacist

Useful questions include: What do you think is causing this? Is it likely to come back, and how can I prevent it? Which products should I stop? How long before I should expect improvement, and when should I come back if it isn't better? Are there side effects to watch for? Is this treatment safe if I am pregnant, breastfeeding or for my child? Writing your questions down, bringing your products (or photos of their labels) and taking dated photos of the problem make an appointment much more useful.