When you use a conjunctive adverb (therefore, however, nevertheless, consequently, for example, on the other hand, moreover, besides, accordingly, thus) to join two independent clauses (complete sentences), precede the adverb with a semicolon and follow it with a comma.
When you combine two complete sentences with any of the words listed in the parentheses above, put a semicolon before the word and a comma after it.I lost my ticket; however, I still attended the play.
Sam disrespected his mother; consequently, he will be driving a tractor to school this fall.
Note that the underlined items in the sentence above are complete sentences; therefore, when you combine the sentences with a conjunctive adverb (don’t worry about what it’s called), use a semicolon before and a comma after.
Some conjunctive adverbs can be used for transition, as an introductory word, or for conversational purposes. If the conjunctive adverb does NOT function by combining complete sentences, set it off with commas.
You, however, are definitely not the person I thought you were.
Billy Bob wrecked my new car. Billy Bob, therefore, is not invited to borrow my speed boat.