US park officials have asked visitors to stop licking psychedelic toads, warning that anyone seeking a hallucinogenic high from the wart-covered amphibians is more likely to end up seriously ill.

The National Park Service posted cautionary messages on social media against licking Sonoran Desert toads, a practice long depicted on popular animated television shows including The Simpsons. "As we say with most things you come across in a national park, whether it be a banana slug, unfamiliar mushroom, or a large toad with glowing eyes in the dead of night, please refrain from licking," said park officials. The toads - among the largest in North America, at nearly 18 centimeters long - secrete a potent toxin from their glands which "can make you sick if you handle the frog or get the poison in your mouth," they wrote.