This is a common question. First let me say a little about what scientists believe causes acne
Scientists believe that there are four major factors that lead to acne: 1) increased production of a protein on the skin which leads plugging of follicles and the creation of "whiteheads;" 2) increased production of an oily substance called sebum that helps to plug the follicles; 3) breakage of the whiteheads which causes inflammation of the skin; 4) and finally a bacteria called p. acnes that lives on the skin and helps to worsen the inflammation.
"Popping" pimples can just make things worse by increasing the amount of inflammation and slowing down the healing process. By breaking open the pimple the increased inflammation can also lead to scarring, which can cause much more long-lasting skin blemishes. Also, by breaking the skin you can create a point of entry for the bacteria that lives on the skin to get deeper into your tissue and cause worse infection or scarring. If you have oily hair that falls on your neck you should work to keep it off your skin. Some of the topical agents also decrease the buildup of the protein that help clog the pores in the first place. Many of the treatments for acne are designed to both decrease the amount of inflammation and the amount of p. acnes that is present on the skin. Using one of these treatments is a better way to control acne than popping the whiteheads. You should talk with your primary care doctor
or a dermatologist
about different options.