Botox has been approved as a treatment for chronic migraine by UK regulators, it has emerged.
A trial carried out with more than 1,300 patients found the medicine, made up of highly refined and purified protein, reduced the frequency of the headaches, the Medicines and Healthcare Products Regulatory Agency (MHRA) said.
The treatment will only be made available to those who suffer headaches at least 15 days a month, with half of those displaying symptoms of migraine, the MHRA said. Approximately 700,000 people in the UK are thought to be chronic migraine sufferers.
Patients were given up to five courses of Botox injections into specific head and neck muscles every 12 weeks as part of the trials.
The study found that after 24 weeks, those treated with Botox experienced fewer days with a migraine than those receiving a placebo. After a year, nearly 70% of those treated with Botox had a 50% reduction in the number of migraines compared with before the trial.
It is not yet clear why the treatment is effective, although Botox is believed to block pain signals as well as acting as a muscle relaxant.