I have read that adding carrots will help tame the heat, although I've never tried it.
Peanut butter works instantly when you've bitten into more than you can handle. Worked wonders for my daughter when she was building up a tolerance. Kind of a funny story, we used to make our own hot sauce every year from chiles in my garden. Usually, cayenne, thai dragons, ripe jalapenos, chipotles and whatever else was in there. We made a batch and let it sit in the fridge for about a week and then took it out to try it. Her boyfriend was over at the time. She commented on how it wasn't as hot as the previous year, but she thought it had a smokier flavor from that year's batch of chipotles. BF wanted in on the tasting and my daughter tried to warn him off but he had seen both of use try multiple tastes seeming unaffected. He tried some on a chip and his eyes bugged out and he started jumping up and down heading for the faucet. I was too busy laughing at him while my daughter got the peanut butter.