Simplify the following text for a Grade 9 native English-speaking person.
Original: Riluzole does not reverse the damage already done to motor neurons , and patients taking the drug must be monitored for liver damage ( occurring in ~ 10 % of patients taking the drug ) and other possible side effects .
Simplified: Riluzole does not heal the damage already done to motor neurons , and patients taking the drug must be watched for liver damage and other side-effects .