When treating a burn, you should apply ice for 5 minutes.

It is not recommended to apply ice directly to a burn. Ice can damage the skin further and delay the healing process. Instead, you should follow these steps when treating a minor burn:

1. Remove the source of heat or potential injury.
2. Cool the burn: Hold the burned area under cool (not cold) running water for about 10-20 minutes. This will help to reduce pain and prevent further tissue damage.
3. Do not use ice, as it can cause further damage to the burnt area.
4. Cover the burn: Use a sterile non-stick bandage or a clean cloth to cover the burn and protect it from infection.
5. Take pain medication if necessary: Over-the-counter pain relievers like ibuprofen or acetaminophen can help alleviate pain.

For more severe burns or burns covering a large area of the body, it is best to seek immediate medical attention.