Cotton, Thong, V-String, Lace, or Cheeky Undies
Issues: Skip the sexy, lacy, skimpy pairs that have bows or ties on them since the fabric rubbing against your skin is sure to cause chafing. If you prefer thongs to prevent unsightly pantie lines, think of the alternative — thongs and v-strings can cause UTIs or other infections. Cotton is a great breathable material, but it's one to avoid when running since it gets heavy when wet and doesn't dry quickly.
Do wear: Stay comfortable and dry with some full coverage wicking undies like these from Isis.