Unpaid leave should not be taken lightly and should be approved according to company policies. In the situation you described, your colleague initially took a legitimate sick leave and obtained a medical certificate. However, if she wishes to continue her leave without seeking further medical advice, she should follow the proper procedures for taking unpaid leave. Generally, unpaid leave can be granted for valid reasons such as personal emergencies or family matters, but it should not be used as a substitute for paid leave just because someone does not feel like going to work. It is important for employees to understand the company's policies regarding leave and to follow the proper channels for requesting time off. In this case, it would be best for your colleague to discuss her situation with HR or management to ensure that the appropriate leave option is chosen.