Since April, Nadia Cwiach has spent every day with her mouth and tongue on fire.
"When it initially started, it was like a burning down my throat. I thought it was reflux or an allergic reaction," Cwiach said.
But after a series of unhelpful allergy medicines and a battery of blood tests, Cwiach's doctors found nothing physically wrong with her.
For Cheryl Jones, it was two years ago, when she was chewing cinnamon-flavored gum.
"I remember chewing the gum and thought that the burning was from that, but my tongue just kept burning," Jones said.
Jones went to her dentist who told her to get a softer toothbrush and to change her toothpaste and mouthwash, but still the burn persisted. The constant, fiery sensation drove Jones to her doctor, who then sent her to another doctor, who sent her to yet another and one more after that.
Her mouth is still on fire, making normally pleasant, everyday acts like speaking and eating quite literally a pain.
This mysterious, constant sensation is known as burning mouth syndrome, and it has both patients and doctors searching for a way to put out the fire. Otherwise known as glossadynia, the chronic condition is associated with nerve dysfunction in the brain and mouth.
The syndrome occurs in less than one percent of the population -- and like many uncommon, nonfatal diseases, research and awareness has been relatively limited. Although the advent of online forums and chat rooms has increased awareness, the syndrome's cause and cure are still burning questions.
People have suffered from burning mouth syndrome since ancient times. Historic writings have mentioned the condition, and the ancient Incas and Egyptians drew pictures depicting the syndrome — with people spewing flames out of their mouths.
Today, a complete understanding of the origins of glossadynia remains elusive; post-menopausal women are the most likely to get the condition, possibly due to hormonal changes. Intense trauma from collisions or accidents can also trigger the sensation.
Whatever the cause, those who suffer from burning mouth syndrome are haunted by a sensation that ranges from irritating to agonizing.
"The only way I can describe it is, it's as if you took a book of matches, lit them and stuck them in your mouth," Cwiach said.
The syndrome has no visible physical signs, but it can be accompanied by dry mouth, metallic or bitter tastes and increased or reduced sensitivity to flavors. One woman had, in addition to the burning sensation, a reduced sense of taste — such that she added so much salt, sugar and spice to dishes, her husband refused to eat them.
Paul Upah, 63, of Denver, has suffered from the condition for two years after an ironic twist of fate: Upah had been tongue tied, a condition in which the flap of tissue connecting the tongue to the floor of the mouth is too short, reducing mobility. Upah finally underwent surgery to fix the problem. But soon afterward he began suffering from burning mouth syndrome.
Since then, Upah has tried almost everything to find relief, from anti-epilepsy medication to acupuncture.
"I've been [to] 20 different doctors, and literally tried every drug they've recommended … and nothing has seemed to work. It's very frustrating," Upah said.
Much of the frustration patients feel arises from the ambiguity of the syndrome and what causes it.