An worker can use endless quantities of sick leave for his or her have critical wellbeing affliction. The Family and Medical Leave Act of 1993 (FMLA). Under the FMLA, an personnel is entitled to a total of 12 function weeks of unpaid go away in the course of any 12-month period of time for specific household and medical requires, including an employee's critical overall health issue. Sick Leave for a Serious Health Condition.