Because of his fear of germs, Mandel didn't tie his shoes, which made walking difficult. "I would try to keep my shoe on so I would drag one foot behind me, because if I lifted my foot the shoe would come off," he said.
To this day, Mandel will not wear shoes with laces.
It wasn't just OCD that Mandel struggled with; he also battled ADHD and the combination of both would prove to make school unbearable.
Mandel said he grew up feeling isolated. He didn't have many friends, especially in high school. Even though he was always looking for a laugh, and loved to play practical jokes, few others saw the humor.
"I became a pariah. I think the thrust of any child is to try to fit in and be part of it. And I can't tell you how many times my humor, you know, what I thought was humor ended up making me the outsider," he said. "Like I'd be, I go, 'it's a joke.' And they'd go, 'well, what was funny?' And they just thought I was insane."
A pattern of elaborate pranks lead to Mandel being expelled. He never finished high school.
Though his sense of humor wasn't popular, his girlfriend Terry found his brand of humor charming. The two have been married for 30 years.
"When I started dating him, and I really knew the real him, I knew how great he was, and how sweet and wonderful and what a great guy he was," she said. "And then there was that other crazy side, which I said, 'Just don't do any of that crazy stuff to me.' I actually thought a lot of it was funny."
Thirty-six years after meeting, the couple has raised three children together, but Mandel's OCD has often made it difficult.
"That was tough. He was like, 'Nobody touch them, wash your hands.' The kids, when they were crawling on the floor, everything bothered [him], it was so hard for him," Terry said.
Mandel has even been known to wear a surgical mask and rubber gloves when loved ones are sick. He admits his issues aren't easy on his family.
"She's a saint, because a lot of people would not put up with the crap that I doll out because I can't cope. [Terry] has that understanding. It's just a lot for her to have to deal with," Mandel said.
While Mandel has a hard time touching strangers, he and Terry are still very much romantic. "I have known [her]. She's healthy, she's clean, it's not like a stranger," Mandel said. "I can hold her, I can kiss her… it's not the same."
Mandel has been on the stage for 30 years. His first big break came April 19, 1978, when he took the stage at a small comedy club in Toronto called Yuk Yuk's. He loved to perform and felt at home in the spotlight. So it's no surprise that he soon became the featured act. Terry kept his horoscope from that day, which reads: "Tonight your life will change forever." And it did.
Less than a year later, Mandel did a set at the famous Comedy Store in Los Angeles. From there his career took off. He would go on to make more than 20 appearances on "The Tonight Show with Johnny Carson." He added acting to his resume in the 80s, playing Dr. Wayne Fiscus for six years on the Emmy Award-winning drama, "St. Elsewhere," and delved in film and voice-over work.
Mandel's only unexplored territory as a performer was hosting his own talk show. That opportunity came in 1998 with "The Howie Mandel Show." During this time, Mandel was still publicly shaking hands, but kept a bucket of Purell under his desk.