Michael Spann didn't realize he was bleeding until a police officer drew her gun on him and shouted a profanity.
"She shined a light in his eyes and started backing up and she drew her gun," his mother, Peggy Spann, told ABCNews.com.
Another time, it happened at a dollar store, prompting the cashier to back up until she hit the counter behind her.
Michael Spann, 29, was bleeding from his eyes.
"He said, 'I'm not going to hurt you,'" said Peggy Spann, a retired nurse. "Once it starts, it's like the floodgates. Three hours."
Spann of Antioch, Tenn., has bled from his eyes for no apparent reason for more than seven years, his mother told ABCNews.com. Although it started as a daily occurrence accompanied by headaches when Spann was 22, he now only bleeds about once or twice a week.
He also bleeds from his nose, mouth and ears during these episodes. There is no cure or relief for his unexplained condition.
The bleeding comes with excruciating headaches, Peggy Spann said. Her son was not feeling well enough to be interviewed by ABCNews.com.
"I felt like I got hit in the head with a sledgehammer," Michael Spann told the Tennessean. of the first time he experienced the bleeding. "I never felt anything like it."
Peggy Spann said she sometimes finds him sitting in her living room, rocking with his head in his hands while he cries because the pain is so bad. He lives with his parents because the bleeding has rendered him unable to keep a job.
Although a friend got Spann a job refurbishing old houses, the clients inevitably catch him bleeding and don't want him in their homes, she said.
Before the bloody tears started, Spann was the family caretaker, delaying college to help his mom after she shattered her leg about a decade ago. Then, he delayed it again after she was in a particularly bad car accident.
The bleeding started just as he was finally ready to leave the house.
"I feel guilty because he hasn't had a life," his mother said. "He feels bad that he's still living here but where else could he go?"
Doctors can't seem to figure out what causes Spann to bleed, and they've been unable to stop it, Peggy Spann said. They paid out-of-pocket to take Spann to the Cleveland Clinic twice, but there was nothing anyone could do.
Calvino Inman, 19, also bleeds from his eyes, which prompted his friends to call him "possessed" in 2009, when he spoke to ABC News affiliate WATE-TV in East Tennessee.
ABC News has been unable to reach Inman.
Dr. James "Chris" Fleming, an ophthalmologist at the University of Tennessee's Hamilton Eye Institute in Memphis, told ABCNews.com that he sees about three cases of bloody tears per year, but they're almost always explained by medical conditions ranging from lesions to cancer to drug use.
Fleming is not treating Spann.
Fleming and four other doctors authored a study in 2004 in which they described four patients whose bloody tears could not be explained in an 11-year period. The patients were between 6 and 14 years old, and their bloody tears have since gone away naturally, he said.
He said bloody tears are usually not painful.