CBD, or cannabidiol, is an extract of the cannabis plant without the tetrahydrocannabinol, the part that induces a high. People who use CBD believe it can help with a range of problems.
The results of a small trial, presented at a meeting of the American Headache Society in Austin, Texas, in June, showed that almost half of those given the air blast treatment were pain-free afterwards.
A face mask, which is worn as soon as symptoms start, is thought to work by reducing inflammation in nerve cells that cause pain. It could be a new treatment for migraine sufferers.