As a child with severe asthma, Dr. S. Scott Nicholas sat on the sidelines and watched other kids play sports. Sometimes, he had to stay in bed under an oxygen tent, often missing school.

“He carried a great big inhaler to high school and would hide in the bathroom to use it so the kids wouldn’t make fun of him,” said his wife, Roz Nicholas.

But the loneliness and hardship Nicholas endured turned him into an empathetic physician who could easily relate to kids and adults suffering from the daily debilitating symptoms of asthma and allergies.

“Spending his childhood bedridden and in and out of the hospital was the motivation for my dad to become a doctor specializing in asthma,” said his son Greg Nicholas.

Nicholas died at age 81 on Oct. 17 at his home in Edina. Sydney Scott Nicholas was born in Des Moines, Iowa, in 1936. “He was Sydney Jr., so everyone called him Scott,” said Kate Rose, his sister.

The sickly boy was often home-schooled, said Rose. Once, when the Nicholas family was visiting relatives in the Twin Cities, he suffered a severe asthma attack. The hospital doctor told his parents, Sydney and Dorothea, that their teenage son wouldn’t live to adulthood. The Nicholases left Des Moines and moved to Minneapolis to be closer to family.

Nicholas graduated from Washburn High School in 1954 and went on to study at the University of Minnesota School of Medicine. “He knew he wanted to become a doctor by high school, that was his passion,” said Roz.

Nicholas earned a master’s degree in internal medicine in 1966 at the University of Michigan. That year, he joined Eisenstadt Allergy & Asthma in Minneapolis, where he treated children and adult allergy sufferers for 52 years, eventually becoming a senior partner.

“His patients adored him,” said Dr. Ramarathinam Nagarajan, a partner at Eisenstadt. Nicholas, considered one of the pioneers in his field, was a clinical professor at the U’s School of Medicine, on the board of the International Committee of the American College of Allergy and Immunology, and president of the Twin Cities and Minnesota allergy societies.

He also was a volunteer physician at Camp Superkids, where children with asthma learn how to manage their disease. Greg Nicholas recalled going on hospital rounds with his dad and visiting patients. “He had a lot of empathy for kids because he had been in their shoes,” he said.

Nicholas also was a good listener and problem-solver, and was warm and caring, said his patients. “He was not only my doctor, but a friend,” said Tom Heffelfinger, an asthma patient since 1975. In fact, Nicholas prescribed a new drug for Heffelfinger and “the amount of therapy I need is reduced dramatically,” he said.

At work every day, Nicholas was dapper, said Roz, “dressed in a suit with a bow tie.”

“He always had a big smile with twinkling blue eyes,” she said.

The popular allergist also was a local radio personality who shared coping strategies for the afflicted during allergy season. Thanks to advances in the treatment of asthma, as an adult Nicholas played tennis, golf, swam and ran around the city lakes with gusto. He would often be seen cruising around Lake of Isles driving a Porsche, wearing his trademark bow tie.

When Nicholas was diagnosed with cancer, “he faced his illness with unfaltering grace,” said Roz. He continued to treat patients until last April, when his cancer became too painful. “He felt guilty he was letting his patients down,” said Greg Nicholas.

“He had a good long life,” said his sister.

Nicholas is survived by his wife, Roz; children Mark Nicholas, Kim Boehland and Greg Nicholas, and sister Kate Rose. Services have been held.