Joe Nagy, a retired chemical engineer from Phoenix, woke up in the middle of one night and a clear liquid dropped out of his nose as he bent his head over, but he didn't worry about it.
"I am getting old -- I'll be 69 in six weeks," said Nagy. "When you get old, different things go wrong with you."
As the drippy nose got more frequent and he developed a cough, his doctors dismissed his symptoms as allergies and prescribed Benadryl. But after several visits to an ear, nose and throat specialist, medical experts came up with a different diagnosis: Nagy was leaking fluid from his brain.
"Oh my God, I was scared to death -- scared, scared scared," said Nagy, who had been carrying a box of tissues around with him for months. "I thought they would have to open up my head to find the leak. Most people who have brain surgery wake up and they are never the same again."
Doctors took a sample of the fluid and his wife of 47 years, Shirley, then head nurse at a local hospital, took it to her lab for testing.
When results came back, doctors realized he had a cerebrospinal fluid leak. The potentially life-threatening condition is rare, occurring in only 1 in 100,000 or 1 in 200,000 patients.
The main danger is infection or getting air in the head that can herniate the brain.
Nagy, in March 2011, went to a local surgeon who failed to close the leak and referred him to Dr. Peter Nakaji,, director of the neurosurgery program at Barrow Neurological Institute in Phoenix.
Since surgery at Barrow in August, "I haven't had a drop out of my nose since," said Nagy.
Nakaji told ABCNews.com that the leak was caused by an "out-pouching" of the brain sac, causing meningitis.
"It was way lateral into his sinus," he said. "Typically, it's midline in the skull.
"It certainly could have killed him," he added. "He was already quite sick at the time."
Though the condition is rare, Nagy is not the first in Arizona to undergo treatment for a brain leak.
Last year, Aundrea Aragon, also of Arizona, noticed a tasteless liquid dripped from her nose whenever she bent over, and her doctors diagnosed it as allergies.
"It wasn't even dripping; it was pouring out of my nose," said Aragon, a 35-year-old mother from Tucson. "If I looked down or bent over, it would literally pour out of the left side of my nose. I had no control at all."
Even though doctors "blew off" her concerns, Aragon said, she knew something was seriously wrong.
"I was literally drinking this fluid and my chest was hurting," she said. 'I was waking up choking on the liquid. I thought I had pneumonia.
"I was walking around my house with paper towels shoved up my nose and changing it every 10 minutes," she said.
Her brain was leaking cerebrospinal fluid through two cracks in the back of her sphenoid sinus, a condition that could have killed her.
"I am still kind of in shock," said Aragon. "I was very fortunate. They said I could get meningitis and go into a coma and die."
Dr. Alexander G. Chiu, chief of the division of otolaryngology at the University of Arizona Medical Center, performed Aragon's surgery last October. He told ABCNews.com at the time that he had only treated 100 cases in his career.
Most often, the condition is seen in overweight patients who have high cranial pressure, and the sinus "pops open." Sometimes a car accident or head trauma can cause a tear. In Aragon's case, doctors didn't know why it happened.