A patient bled green, surprising surgeons. Something from Star Trek? No, simply high doses of Imitrex. Who knew?

The patient had been taking large doses of sumatriptan – 200 milligrams a day.

This had caused a rare condition called sulfhaemoglobinaemia, where sulphur is incorporated into the oxygen-carrying compound haemoglobin in red blood cells.

Describing the case in The Lancet, the doctors led by Dr Alana Flexman from St Paul’s Hospital in Vancouver wrote: “The patient recovered uneventfully, and stopped taking sumatriptan after discharge.

“When seen five weeks after his last dose, he was found to have no sulfhaemoglobin in his blood.”