DermUV
ABCDE Rule
ABCDE is the dermatology mnemonic for melanoma self-exam: Asymmetry, Border, Color, Diameter, Evolving.
ABCDE Rule explained
Any mole that is asymmetric, has irregular borders, multiple colors, is larger than 6 mm, or is changing should be reviewed by a dermatologist. Most melanomas detected at the ABCDE stage are still highly curable.
Related terms
Terms related to ABCDE Rule connect the UV and sunscreen topic cluster.
Related DermUV pages
Continue with reference material and live city UV forecasts.
Using ABCDE Rule in practice
UV strength on this page follows solar elevation, ozone thickness, cloud cover, altitude, and surface reflection. Snow can bounce back most of the UV that hits it, water and sand far less, but all of them add to the dose skin receives.
Burn-time figures come from minimal erythemal dose (MED) values published for each Fitzpatrick skin type, divided by the erythemal irradiance at a given UV index. Personal MED varies by roughly 20 percent, so treat every number as a planning range.
Reapplication matters more than the SPF number. Reapply roughly every two hours outdoors and immediately after swimming, heavy sweating, or towelling, regardless of what the bottle claims.
Cumulative dose drives photoaging and long-term skin damage more than any single day. Small daily exposures on commutes, walks, and driving add up across a season.
Plan outdoor blocks around the peak UV window, usually between 10am and 4pm local time. Shade, UPF fabric, a wide-brim hat, and UV-blocking sunglasses reduce dose more reliably than sunscreen alone.
UV scale reference
The WHO scale groups UV 1-2 as low, 3-5 as moderate, 6-7 as high, 8-10 as very high, and 11 or above as extreme. Protection is recommended from UV 3 upward, and shade during the middle of the day becomes the priority from UV 8 upward.
A practical routine at moderate-to-high UV is roughly one ounce of broad-spectrum sunscreen for full-body coverage, applied 15 minutes before going out, then reapplied on schedule. Clothing, hats, and shade carry the rest of the load, especially for children and anyone with a history of easy burning.
Keep exploring DermUV
These pages give more depth around abcde rule, from UV-scale reference material to definitions and city forecasts.
- UV index by city
- Activity UV guides
- Fitzpatrick skin type scale
- UVA definition
- What UV index 8 means
- What UV index 3 means
- BROAD-SPECTRUM definition
DermUV forecast values come from Open-Meteo UV data (CC BY 4.0) and are refreshed throughout the day.