Synthetic marijuana-related hospitalizations skyrocket in US

Over 1,500 cases have been reported in US since April, as overseas manufacturers circumvent regulations with dangerous new variations of legal highs

A huge spike in hospitalizations last month caused by a class of drugs often called "synthetic marijuana" illustrates the potency and dangers of the chemicals used to make them and the shifty tactics authorities believe manufacturers are using to evade regulation.

Poison control centers around the US reported 359 cases in January of illnesses from synthetic cannabinoids, which mimic the effects of the main psychoactive ingredient in marijuana but can be far more potent. There were 273 in February and 269 in March. But the number skyrocketed to just over 1,500 in April, according to the American Association of Poison Control Centers.

Related: 'Our purity is above 99%': the Chinese labs churning out legal highs for the west