Summary

We report the challenges of treating relapsing-remitting multiple sclerosis (MS) in a 31-year-old woman with long-standing chronic idiopathic neutropenia. The treatment with the disease-modifying therapy interferon-β was significantly complicated by a further fall in her generally low neutrophil count, to values below 0.5×10⁹/l, although this recovered rapidly when the treatment was stopped. We discuss the difficulties of balancing the risk of neutropenia with a risk of MS relapse.