If you are 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 cannot be seen.
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 is not the only method of communication.
Consider representing RAG ratings in the same way: