I am confused if I should use past perfect tense or present perfect tense in this sentence.
Herbal teas have been used for medication (for centuries) before pills were invented.
Herbal teas had been used for medication (for centuries) before pills were invented.
1.I can use present perfect tense because some people still use herbs for medication..But they are not prescribed anymore I think.
2.Because the part "pills were invented" is in the past form should the part "Herbal teas have been used" be past form also