Interferon beta but not glatiramer acetate therapy aggravates headaches in MS.

Type and frequency of headaches during immunomodulatory therapy in MS were determined in 167 consecutive patients. In a prospective group of 65 patients beginning interferon beta therapy, headache frequency and duration increased in 18% of all and in 35% of patients with pre-existing headache by more than 50% during the first 6 months. In two retrospective groups, increased headache frequency was reported by 34% of 53 patients on interferon beta, but by only 6% of 49 patients during at least 6 months of glatiramer acetate therapy.