Question

Do I put a semicolon or a period before "otherwise"?

Answer 1

Generally, neither.

Explanation:

"Otherwise" is a word used to show the result of an action or suggested action. For instance:

"You'd better slow down your eating otherwise you'll end up with a stomach ache."

"Otherwise" links two thoughts - one is the "you'd better..." and the other is the consequence or alternative to not listening.

When we use a period or semicolon, we are keeping one thought separate from another thought - the semicolon will show thoughts that are roughly equal and the period is a hard stop and so anything can follow it. For instance:

"You'd better slow down your eating; you'll end up with a stomach ache."

or

"You'd better slow down your eating. You'll end up with a stomach ache."

So using "otherwise" and using a semicolon or period before it is operating at cross purposes.