How often should I check my skin?

A reasonable rhythm for most people is once a month. That's often enough to notice when something is new or changing, and monthly repetition helps you learn what's normal for your own skin. If you have a lot of moles, fair skin, a history of sunburns or tanning beds, or a personal or family history of skin cancer, talk to a dermatologist about how often you should be checked in person, too.

What's the difference between a normal spot and a worrying one?

The two most useful tools are the ABCDEs (Asymmetry, Border, Color, Diameter, Evolving) and the 'ugly duckling' sign — a spot that simply looks different from your others. Most of your moles tend to resemble one another; the one that stands out, or that is new or changing, is the one worth showing a doctor. You do not need to diagnose it yourself — you just need to notice it and get it looked at.

Can an at-home app or photo tool tell me if a spot is cancer?

No — and you should be cautious of anything that claims it can. No photo, app, or automated tool can diagnose skin cancer; that requires a clinician and often a biopsy. Photographs are genuinely useful for tracking whether a spot is changing over time, but a diagnosis is a doctor's job. If a spot worries you, book an in-person visit rather than relying on any tool.

How to Do a Skin Self-Exam (and What to Look For)

Checking your own skin is one of the simplest, cheapest things you can do for your long-term health — and skin cancer found early is highly treatable. For melanoma, the most serious skin cancer, the five-year survival rate is around 97% when it's caught at the earliest stage, and far lower once it has spread (StatPearls). The whole point of a self-exam is to catch changes early and get anything suspicious in front of a professional.

Here's how to do one properly — and, just as importantly, what a self-exam can't do.

How often, and what you need

Aim for a monthly check. Doing it regularly is what makes it work: you're building a mental picture of what's normal for your skin, so a new or changing spot stands out.

You'll want a well-lit room, a full-length mirror, and a hand mirror — plus a partner or a phone camera for the spots you can't see (your back, scalp, and the backs of your legs). Take your time; a thorough check takes about ten minutes.

The step-by-step check

The American Academy of Dermatology recommends going over your entire body, front and back (AAD). A simple top-to-bottom order so you don't miss anything:

Face, ears, neck, and scalp. Use the hand mirror for behind your ears, and part your hair (or use a comb/blow-dryer) to see your scalp.
Torso and underarms. Facing the mirror, then with arms raised. Women should check under the breasts.
Arms and hands. Both sides of your arms, then palms, backs of hands, between the fingers, and under the nails.
Legs and feet. The fronts, then use the hand mirror for the backs. Don't skip the soles, between the toes, and under the toenails — melanoma can appear on skin that rarely sees the sun.
Buttocks and genital area, using the hand mirror.

Remove nail polish before you check, so you can see the nail beds — a new dark streak under a nail is one of the signs worth taking seriously (more in what your nail changes can mean).

What you're looking for: the ABCDEs

For moles and pigmented spots, dermatologists use the ABCDEs of melanoma (AAD):

A — Asymmetry: one half doesn't match the other.
B — Border: irregular, scalloped, or poorly defined edges.
C — Color: more than one color, or an uneven mix of tan, brown, black, red, white, or blue.
D — Diameter: larger than about 6 mm (a pencil eraser) — though melanomas can be smaller.
E — Evolving: the spot is changing in size, shape, or color, or is new.

Of these, E is the one to weight most. A spot that is changing, or that itches, bleeds, or won't heal, deserves attention regardless of how it scores on the others.

The "ugly duckling" sign

There's a second tool that's just as useful and easier to remember. Most of your moles tend to look like one another — a family that shares a general size and color. The ugly duckling is the spot that breaks the pattern: the one that stands out from its neighbors (AAD). If one spot makes you look twice because it just doesn't match the rest, that's the one to show a doctor.

Keep a record

Because the real signal is change over time, a simple record helps enormously:

Take photos of any spots you want to keep an eye on, ideally with something for scale (a coin or a ruler) in frame.
Note the date and the location on your body.
Re-photograph at your next monthly check and compare.

This is exactly where photographs earn their keep — not for diagnosis, but for tracking. If you're documenting a spot, our guide on what photos to take for a skin assessment covers how to get clear, comparable images.

What a self-exam can't do

A self-exam is for noticing, not diagnosing. No self-check — and no photo, app, or automated tool — can tell you whether a spot is cancer. That takes a clinician and, often, a biopsy. A private skin assessment can help you describe and document a spot you're worried about, but for anything possibly cancerous it is informational only and not a substitute for a doctor. Your job is to spot the change; a professional's job is to diagnose it.

When to see a doctor

Make an appointment with a board-certified dermatologist if you notice (AAD):

A spot that is new, changing, or different from your others (the ugly duckling).
A mole or patch that itches, bleeds, crusts, or won't heal.
A dome-shaped or pearly bump, a rough or scaly patch that persists, or a non-healing sore.
A dark streak under a fingernail or toenail.

None of these means you have cancer — most such spots turn out to be harmless. But they're exactly the things a professional should look at, and finding skin cancer early is what makes it so treatable. When in doubt, get it checked.