UNDATED (AP) - Synthetic substances that mimic marijuana, cocaine and other illegal drugs are making users across the nation seriously ill, causing seizures and hallucinations and even killing some.

The inexpensive products are often packaged as incense or bath salts. As more people experiment with them, hospitals are seeing a sharp spike in the number of patients with problems ranging from labored breathing and rapid heartbeats to extreme paranoia and delusions.

At the request of The Associated Press, the American Association of Poison Control Centers analyzed nationwide figures on calls related to synthetic drugs.

At least 2,700 people have fallen ill since January, compared with fewer than 3,200 cases in all of 2010. At that pace, medical emergencies related to synthetic drugs could go up nearly fivefold by the end of the year.

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