Population: adult subjects, submitted to hematopoietic stem cell transplantation (HSCT) at a cancer hospital in the interior of São Paulo State. The following inclusion criteria were adopted for sample selection purposes: subjects over 18 years of age, candidates for allogeneic HSCT and with intact oral cavity on the first day of conditioning. Subjects will be excluded if they present any adverse reaction to the active principles of Chamomilla recutita; receive oral or intravenous anticoagulation therapy; use oral or systemic topical anti-inflammatory medication; receive any other type of intervention for mucositis not included in the standard oral care protocol.