toothpaste
I doubt it matters what kind of toothpaste, but don’t know. Probably
the bargain stuff. The actress who played Chrissy Snow on Three’s Company
had a book published called "Secrets." As a child, there was no extra money
for anything like clearisil so, when she got a pimple, she’d clean her face
before bed, apply a dab of toothpaste and let it dry overnight. In the
morning, she’d do her morning routine and the pimple was "gone."
Be warned, however, that toothpaste is extremely drying … before I
married my DH who uses appropriate materials such as spackling, I used to use
toothpaste to fill in nail holes in the drywall whenever I rearranged
pictures … it’s actually quite an effective compound for that 
I’ve actually heard so much more enticing information about potatoes
being anti-inflammatory and shrinking a pimple down quickly, but it’s so
awkward to slice and hold … you might consider a paste of real dehydrated
potato flakes and aloe juice, as it sounds as or more effective and
definitely gentler and less drying (Mmmmm).
- Katie