Does it matter what toothpaste you use? YES, "toothpaste usually contains alcohol--which dries the pimple--and contains drying components like chalk. If you have very dry skin, do not use a toothpaste with a lot of alcohol. Toothpaste's drying components collect moisture and oil from the skin, drawing it out of the pimple." (ehow.com) Also, gel toothpastes don't hold up as well as regular toothpaste because it doesn't dry out enough like the regular toothpaste does to help get rid of redness/swelling as well as it doesn't absorb much moisture from pimples.
So this quick inexpensive fix is good to try and see how it works with your skin. Just test it on on a small area before covering your whole face (if it's needed). Also try peppermint toothpaste for a cooling sensation for irritated areas!