Severe vaginal bleeding associated with recombinant interferon beta-1B

To report a case of severe vaginal bleeding associated with interferon beta-1b (IFN-beta).

A 19-year-old white woman diagnosed with multiple sclerosis was treated with IFN-beta 4 million IU every other day for 1 month. After 1 month, the dosage was increased to 8 million IU. The patient subsequently experienced severe vaginal bleeding. Because her hemoglobin was 3.9 g/dL, she was admitted to the hospital for treatment and observation. IFN-beta was discontinued and she was treated with conjugated estrogens and received 2 units of packed red blood cells. The bleeding ceased and the patient was discharged in stable condition.

Menstrual disorders of mild-to-moderate severity were reported during clinical trials with IFN-beta. This is the first case report regarding severe vaginal bleeding probably associated with IFN-beta. The mechanism for development of IFN-beta-related menstrual disorders is unknown.

Reports of menstrual disorders associated with recombinant IFN-beta are rare; however, clinicians should be aware that this complication can occur. Should menstrual disorders occur with no other etiologic factors identified, IFN-beta should be discontinued, with improvement expected shortly thereafter.