Using red and green

If you’re using red to signal “warning,” or “caution,” and green to signal “approval” or “correctness” consider adding a symbol to make sure colour-blind users can still understand the message.

Traffic lights use red and green, but the position of the lights communicates “stop” or “go”, even if the colours can’t be seen.

Normal vision

Appearance for someone with red-green colour-blindness

When the use of red and green is unavoidable, for example RAG (red, amber, green) ratings make sure that colour isn’t the only method of communication.

Consider representing RAG ratings in the same way: