Methimazole is an anti-thyroid drug that can cause life-threatening neutropenia in rare situations. The aim of this case report is to describe a set of oral complications associated with methimazole-induced neutropenia and the healing of the gingiva after proper treatment.

A 31-year-old female patient hospitalized for systemic symptoms of sore throat and fever and showing extensive gingival necrosis with pain was referred to the Department of Periodontics from the Department of Endocrinology. Methimazole-induced neutropenia was diagnosed based on blood test results and her medical history. Methimazole was discontinued and a range of treatments was administered, including the injection of granulocyte colony stimulating factor.

After systemic treatment, the gingiva began to heal as the neutrophil count increased. Approximately one year later, the gingiva had returned to a normal appearance. Twenty-one months after treatment, sequestra of the alveolar bone that had broken through the gingiva were removed. Periodic supportive periodontal treatment has been continued uneventfully.

The oral manifestations of gingival necrosis and ulcerations, in combination with systemic symptoms such as fever and sore throat, are the critical signs presented in the early stages of drug-induced neutropenia. Therefore, dentists need to be aware of these oral complications in order to make an accurate diagnosis and to ensure that prompt medical intervention is provided.