M1 is a first degree misdemeanor, which is the highest misdemeanor in Ohio. The next higher charge is a fifth degree felony. A M1 charges is punishable by up to 180 days (6 months) in jail and up to $1,000 fine, this would also be in addition to court costs, and there is always other orders by the court, like restitution, probation, treatment, community service, and other miscellanous orders.
You should also realize that some M1 charges carry with it mandatory driver license suspension or increased penalties for subsequent charges. Therefore, your boyfriend should consult an attorney to fully understand the consequences of his charge.