Biting into a raw jalapeño will probably create quite a sting, but on the pepper scale of heat (the Scoville Scale), jalapeños are not really that hot. If you seed and core the pepper, you may not get any heat at all out of a jalapeño.
Some jalapeños are hotter than others. Mature peppers that are dark green and a little wrinkled will be hotter than younger ones. The hottest jalapeños are grown in the hot, dry climates of New Mexico or Arizona.
If you don’t know where a jalapeño was grown, you may have to taste it yourself to measure the heat. Don’t rely on someone else to tell you whether or not a pepper is too hot. Some people are more sensitive to capsaicin (the chemical that makes hot peppers hot) than others. In junior high, I watched a guy drink a bottle of Tabasco on a dare. He didn’t even dab his forehead. If you want to try that at home, you can build up your tolerance to capsaicin by eating more chile peppers and hot sauce.
My father-in-law, Billy, eats raw jalapeños whole from tip to stem. He tells me they are good for his health, and the American Dietetic Association agrees. Peppers are rich in phytochemicals that appear to provide anti-inflammatory benefits. Medical studies show that capsaicin may act as a blood thinner. Spicing dishes with cayenne or pepper flakes also reduces the need for extra salt. Hot sauce, which is actually more salt than pepper, is another story. - Elizabeth Hughey