US drugmaker Allergan said Botox had been licensed by British regulators for the prevention of headaches in adults with chronic migraine.

Historically, treatment for chronic migraine has consisted of a combination of over-the-counter and prescription treatments such as triptans, tricyclic antidepressants, beta-blockers and anti-epileptics.

"The authorization of Botox marks an evolution in medical care for the prevention of headache in adults with chronic migraine. It is also a significant milestone in the history of Botox and Allergan," said Scott Whitcup, Allergan's head of research and development.