YSK that if you're buying an over-the-counter brand name drug in the United States there is often a much cheaper generic alternative that is exactly the same but often much cheaper.
from /r/YouShouldKnow
YSK，如果你在美國購買非處方品牌藥，往往有一個便宜得多的仿製藥替代品，完全相同，但往往便宜得多。