Depends on what you're talking about exactly.

If it's chafing/abrasion - calendula ointment or Nubutte (which is useless as a lubricant IMO, but nice as a healing ointment)

If it's small pimples - thoroughly wash and pat dry, then dry with rubbing alcohol or alcohol gel (careful where that goes! )

If it's a large pimple or boil - squeeze or pop it with a needle to remove the blockage, then clean and dry the same as with small pimples