Rare Ritalin Side Effect: Painful Erections FDA issues warning about attention-deficit drugs By John Johnson, Newser Staff Posted Dec 20, 2013 1:00 PM CST 12 comments Comments The FDA has issued an unusual warning about Ritalin and other drugs with the chemical methylphenidate. (Flickr) (Newser) – Labels on Ritalin and other drugs used to treat ADHD will soon have a new warning: Beware long, painful erections. It seems that a chemical in the drugs called methylphenidate is a stimulant that can mess with the body's central nervous system, explains Vocativ.com. It “may in rare instances cause prolonged and sometimes painful erections known as priapism," says an FDA warning. Cases have been seen in kids as young as 8 years old, notes Reuters. "Younger males, especially those that have not yet reached puberty, may not recognize the problem or may be embarrassed to tell anyone if it occurs," says the FDA. And that's a real concern because the problem can cause permanent damage to the penis. Methylphenidate is found in Ritalin, rival Concerta, and generic forms of both.