ABCDE Rule: How to Spot Dangerous Skin Changes Early

When it comes to skin cancer, catching it early can mean the difference between a simple removal and life-saving treatment. The ABCDE rule, a simple, widely used method for identifying potentially cancerous moles. Also known as the melanoma checklist, it gives anyone a quick way to check their skin without needing a doctor’s office. This isn’t just for people with lots of moles—it’s for everyone. Skin cancer doesn’t pick and choose; it shows up on fair skin, dark skin, young people, and older adults alike.

The ABCDE rule breaks down what to look for into five clear signs. Asymmetry, when one half of a mole doesn’t match the other is the first red flag. Then there’s Border irregularity, where the edge looks ragged, notched, or blurred instead of smooth. Color variation, including multiple shades of brown, black, red, white, or blue within one spot is another warning. A mole larger than 6 millimeters—about the size of a pencil eraser—is a red flag under the Diameter rule. And finally, Evolution, meaning the mole is changing in size, shape, color, or texture over weeks or months. That’s the most important one. A mole that just started changing, even if it looks small, needs attention.

You don’t need to be a dermatologist to use this. Check your skin once a month—after a shower, when you’re already looking at yourself. Use a mirror for your back, or ask someone to help. Take photos if you’re unsure. The posts below show real cases where people missed early signs, misread a mole as a pimple or freckle, or waited too long because they thought it was "just a spot." Others found cancer early because they followed the ABCDE rule and acted fast. Some stories are about people who never thought they were at risk. Others are about parents checking their kids’ skin. You’ll also find guides on how to document changes, when to go to a doctor, and what happens during a skin biopsy. This isn’t about scaring you. It’s about giving you a tool that’s simple, free, and could save your life.