Once bitten twice shy

Generated image of a woman scared of a dog
Once bitten, twice shy means that after someone has a bad experience, they become more careful about similar situations in the future. It describes how people learn to avoid repeating the same mistake.

The idea appears in very old proverbs. A similar saying was written in the 1600s, comparing a person who has been bitten by a dog to someone who becomes cautious even around friendly dogs afterward.

After losing money in a risky investment, she was once bitten, twice shy about trying another one.