You can set your sickness parameters under the Sickness tab of your Company Settings. 

Under the Sickness section on this page, you will find fields for max sickness days and max sickness instances. These are the number of days or instances staff are allowed to take off sick within a holiday year before triggers are hit.

If you tick the option above these fields to send excessive sickness notifications then the system will trigger email notifications to line managers and admins whenever a staff member reports sickness events that exceed the parameters you have set.