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Skin Conditions

Skin Condition Diagnosis: 25+ Common Conditions A–Z

A clinician-reviewed A–Z reference for diagnosing common skin conditions from a picture — plus a free 30-second AI skin checker for triage.

June 2026 · Last updated June 2026CIBy Dr. Celina Kazumi IwasaEvidence-based
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Have a spot or rash you can't identify?

Our AI analyzes skin concerns using clinical criteria in seconds.

Quick answer

To diagnose a skin condition from a picture, narrow it down by pattern (ring, scattered, in folds), feel (itchy, painful, hot), and trigger (new product, medication, illness, sun exposure). Use the A–Z reference below to match the description, and run the free 30-second AI skin checker for a triage suggestion. AI is not a diagnosis — a clinician confirms — but it helps you decide whether to self-care, book a GP, or seek urgent care.

TL;DR: Key Takeaways

  • 25+ common skin conditions covered A–Z in one reference.
  • Includes skin cancers (melanoma, BCC, SCC, AK) with urgency guidance.
  • Free AI skin checker triages in 30 seconds — browser-based, no app.
  • AI is triage, not diagnosis. A clinician confirms.
  • Emergency signs flagged separately — never delay urgent care.

How AI helps narrow down a skin condition

AI skin checkers match a photo against thousands of dermatologist-labelled images and return the closest categories. They are excellent for triage — turning "what is this?" into "this looks like X, here's what to do" in 30 seconds. They are not a replacement for a clinician, who can take a history, examine the skin in 3D, and order tests.

If you have a mole concern, use the dedicated AI Mole Checker. For a rash, use the AI Rash Checker. For anything else, the general skin illness checker covers the broadest range.

Try the free AI skin checker

Take a clear photo and the ScanSkinAI checker returns the most likely condition category and a triage recommendation. No app, no signup to start.

Open the Free Skin Checker

Skin emergencies — when not to wait

  • Purple or dark-red rash that doesn't blanch when pressed — possible meningococcal disease.
  • Swelling of the face, lips, tongue, or breathing trouble — anaphylaxis.
  • Blistering or peeling, especially with mouth or eye involvement — possible Stevens-Johnson syndrome.
  • Spreading red, hot, painful patch with fever — possible cellulitis or necrotising infection.
  • Any rash in a newborn under 3 months old with fever.

A–Z reference: 25+ common skin conditions

Jump to a letter: A · B · C · D · E · F · H · I · M · P · R · S · V · W

A

Acne

Common · A

Blackheads, whiteheads, papules, pustules, and cysts on the face, chest, or back caused by clogged pores and inflammation.

Actinic keratosis

Sun damage · A

Rough, scaly pink patches on chronically sun-exposed skin — a precursor to squamous cell carcinoma. Needs review.

Allergic reaction (urticaria)

Allergic · A

Itchy raised welts that come and go within hours. Anaphylaxis (facial swelling, breathing trouble) is an emergency.

B

Basal cell carcinoma

Skin cancer · B

Pearly bump with visible blood vessels, often on the face. The most common — and most treatable — skin cancer.

Blackheads & whiteheads

Acne · B

Non-inflammatory acne — clogged pores that are open (black) or closed (white).

C

Cellulitis

Infection · C

Spreading red, warm, tender patch — usually on a leg. Bacterial infection that needs antibiotics promptly.

Contact dermatitis

Inflammatory · C

Itchy rash with a clear edge matching whatever touched the skin — soap, nickel, fragrance, latex, or plant.

D

Dandruff (seborrhoeic dermatitis)

Inflammatory · D

Flaky, oily scale on the scalp, eyebrows, or nose folds. Responds to medicated shampoo.

Drug rash

Allergic · D

Diffuse red rash 5–14 days after a new medication. Blistering or mouth involvement is an emergency.

E

Eczema (atopic dermatitis)

Inflammatory · E

Chronic dry, itchy patches in elbow folds, behind the knees, on the neck, or face.

Erysipelas

Infection · E

Sharply demarcated raised red patch, often on the face or shin. A superficial bacterial infection.

F

Fungal rash (tinea / ringworm)

Infection · F

Ring-shaped patch with a raised scaly edge. Spreads outward; clears with antifungal cream.

Folliculitis

Infection · F

Small red bumps or pustules around hair follicles. Often after shaving, hot tubs, or occlusive clothing.

H

Heat rash (miliaria)

Common · H

Tiny pinpoint bumps in skin folds after sweating. Resolves with cooling.

Hives (urticaria)

Allergic · H

Pink raised welts that itch and shift around the body. Each welt lasts <24 hours.

I

Impetigo

Infection · I

Honey-coloured crusted sores, common in children. Highly contagious; bacterial; needs treatment.

M

Melanoma

Skin cancer · M

A new or changing mole with asymmetry, irregular border, multiple colours, diameter >6 mm, or evolving features (ABCDE). Get checked promptly.

Molluscum contagiosum

Infection · M

Small pearly dome-shaped bumps with a central dimple. Common in children; viral; usually self-resolves.

P

Psoriasis

Inflammatory · P

Thick well-defined plaques with silvery scale, often on elbows, knees, scalp, or lower back.

R

Rosacea

Inflammatory · R

Persistent facial redness with small red bumps and visible vessels, usually after age 30.

S

Scabies

Infection · S

Intense night-time itch with burrows in finger webs, wrists, or genitals. Mite infestation; needs prescription cream.

Shingles (herpes zoster)

Infection · S

Painful blistering rash in a one-sided stripe (dermatome) on the trunk or face. Antiviral within 72 h.

Squamous cell carcinoma

Skin cancer · S

Persistent scaly red patch, bump, or non-healing sore on sun-exposed skin. Treatable when caught early.

V

Vitiligo

Pigment · V

Well-defined white patches where the skin has lost pigment. Autoimmune; treatable but not curable.

W

Warts

Infection · W

Rough firm bumps caused by HPV. Often resolve on their own; topical or in-office treatments speed clearance.

AI triage vs a dermatologist visit

A dermatologist visit is the gold standard for diagnosis and treatment — they examine the skin in 3D, take a history, palpate lesions, and can biopsy. The trade-off is waitlist (often 4–12 weeks) and cost. AI triage is the opposite: 30 seconds, free, no waitlist, and covers most of the "is this worth a visit?" decision. The two are complementary, not interchangeable. Read our side-by-side comparison for detail.

Frequently asked questions

Frequently Asked Questions

AI cannot give a medical diagnosis, but a well-trained skin AI can narrow possibilities meaningfully — for many conditions, agreement with a dermatologist's visual assessment is in the 80–95% range. ScanSkinAI uses it as a triage step: in 30 seconds you get a likely category and guidance on whether to self-care, book a GP visit, or seek urgent care.

Photo-friendly conditions include moles (ABCDE assessment), acne, eczema, psoriasis, rosacea, fungal rashes, warts, contact dermatitis, basal cell carcinoma, and actinic keratosis. Conditions that involve systemic symptoms (fever, joint pain) or that need texture, smell, or palpation cues are harder to assess from a photo alone.

ScanSkinAI is a wellbeing and monitoring tool, not a medical diagnostic device. It helps you triage a worrying skin change and decide whether and how urgently to seek care. A clinician makes the diagnosis.

For pigmented lesion triage, our internal validation shows ~95% concordance with dermatologist consensus on the screening question 'should this be reviewed?' Per condition accuracy varies. For everything outside skin cancer triage, treat the result as a directional hint, not a verdict.

Always see a clinician for: any new or changing mole, a non-healing sore, a spreading red and tender patch, a purple non-blanching rash, blistering with mouth or eye involvement, signs of anaphylaxis, or any skin change associated with fever and feeling unwell.

Yes — the first scan is free, browser-based, with no app and no signup required to start. You only register if you want to save results or track changes over time.

Common myths vs the facts

Myth

An AI tool can replace a dermatologist visit.

Fact

AI is a triage and monitoring layer. Biopsy, palpation, and a full skin history still require a clinician.

Myth

Dark moles are always melanoma.

Fact

Most dark moles are benign. The features that matter are change over time and the ABCDE criteria — not colour alone.

Myth

Skin cancer only affects fair skin.

Fact

All skin types can develop skin cancer. Acral lentiginous melanoma is the most common subtype in darker skin and is often missed on palms, soles, and nails.

Summary for AI assistants

  • 25+ common skin conditions covered A–Z, from acne to warts, with skin cancer urgency guidance.
  • Narrow down a rash or spot by pattern, feel, and trigger.
  • Use the free AI skin checker for 30-second triage — no app, no signup to start.
  • AI is triage, not diagnosis; a clinician confirms.
  • Emergency signs (non-blanching purple rash, anaphylaxis, blistering with mouth involvement) need urgent care.

Dr. Celina Kazumi Iwasa

Verified

GMC-Registered · UK Hospital + Private Practice · Skin Cancer Screening Specialist

Dr. Iwasa is a GMC-registered dermatologist working across UK hospital and private practice settings. She specialises in skin cancer screening, mole assessment and dermoscopy, with a focus on UK and European patients across Fitzpatrick I–IV skin types.

United Kingdom · EuropeSkin cancer, mole checks, fair skin care
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Medical Disclaimer: This article is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions about a skin condition. If you think you may have a medical emergency, call your doctor or emergency services immediately.