Most adults have somewhere between ten and forty moles, and the overwhelming majority will never cause a problem across an entire lifetime. The goal is not to worry about every mole — it is to know the specific pattern that actually warrants a proper look, so you can stop worrying about the rest.
The ABCDE rule, and what each letter is actually checking for
Asymmetry: one half of the mole not matching the other, as opposed to a roughly round or oval, symmetric shape. Border: edges that are ragged, notched, or blurred, rather than smooth and well-defined. Color: multiple colors within a single mole — shades of brown, black, red, or blue together — rather than a single, uniform color throughout. Diameter: generally, greater than 6 millimetres, roughly the size of a pencil eraser, though this is a guide, not an absolute cutoff, since concerning changes can occur in smaller moles too. Evolution: any mole that is changing — in size, shape, color, or sensation — over weeks to months. Of these five, evolution is arguably the single most important, because a mole that is genuinely changing is more concerning than a static mole that happens to have one borderline feature.
Why "the ugly duckling" matters as much as any individual criterion
Dermatologists also use a simpler practical heuristic: does a particular mole look meaningfully different from the person's other moles. Most people have a personal pattern to their moles — a mole that clearly stands out from that pattern, even if it does not obviously meet several ABCDE criteria individually, is worth having checked specifically because it breaks the person's own baseline.
Other symptoms worth mentioning beyond appearance
A mole that itches persistently, bleeds without an obvious injury, becomes tender, or develops a crust that does not resolve are all symptoms worth raising, independent of how the mole looks visually.
Who has a genuinely higher baseline risk
Fair skin that burns easily rather than tans. A large number of moles, generally more than fifty. A personal or family history of melanoma. A history of significant sunburns, particularly blistering sunburns in childhood or adolescence. Regular use of tanning beds. These factors do not mean routine self-checks need to become anxious, but they do mean a slightly lower threshold for having a new or changing mole looked at, and often a case for a periodic full-body skin check with a dermatologist regardless of whether any specific mole looks concerning.
What a self-check actually involves
A monthly check, ideally with a partner's help for hard-to-see areas like the back and scalp, comparing your moles against how they looked previously — which is why taking photos periodically is genuinely useful, since memory for exactly what a mole looked like months ago is unreliable.
What actually happens if a mole looks concerning
A dermatologist typically examines it with a dermatoscope, a specialized magnifying tool that reveals pigment patterns not visible to the naked eye, which considerably improves the accuracy of the visual assessment before deciding whether a biopsy is warranted. Many moles examined this way turn out reassuring without needing a biopsy at all.
The honest summary
Most moles need nothing more than the occasional glance. The ABCDE rule, evolution in particular, and the ugly-duckling comparison are what separate the ones actually worth a dermatologist's look from the many that are not.
This article is educational and does not replace an individual consultation. If a mole meets several ABCDE criteria, has changed recently, or is bleeding or persistently symptomatic, have it examined by a doctor or dermatologist rather than monitoring it yourself.