Do you remember that Frasier episode where Niles had a persistent toothache, and speculates it may be referred pain? This ends up being true when, on an EKG, Niles finds out he was experiencing a walking heart attack for days without realizing it. Soon, he is rushed to the hospital for heart surgery.

So, is this simply a fictional plot line or is there actual potential that a toothache could be something much more serious?

The case of a referred pain toothache

First, it’s important to understand what referred pain actually is. “Referred pain is a neurologic reaction in which pain in one area can be felt in another,” says Dr. Rhonda Kalasho, a double board-certified dentist based in Los Angeles.

According to Kalasho, referred pain is an common phenomenon of the mouth. “It is an incredibly interesting phenomenuem but ever more a reason you should see a dentist so that your doctor can help you differentiate the root cause of the dental pain,” she says.

So, yes, Niles’ walking heart attack in the Frasier episode is a real, albeit rare, possibility. “[There is indeed] a possibility that dental pain could be indicative of a more serious issue,” confirms Kalasho.

When tooth pain is something more

Though referred pain is often difficult to diagnose, it can be an imperative warning sign in some cases.

In rare cases, a referred pain toothache can be an alarming symptom of a heart attack or lung cancer.

According to Henry Hackney, DMD, a Doctor of Dental Medicine and the Director of content at Authority Dental, a referred pain toothache can be an alarming symptom of a heart attack or lung cancer. “This is due to the vagus nerve location,” says Hackney. “As [the vagus nerve] connects our body and brain, the pain can run through it [and cause] jaw pain.”

More specifically, the left vagus nerve enters the thorax (aka the house of the heart and lungs) and descends on the aortic arch, which then could cause referred pain from the lungs and heart to the sinuses or craniofacial region (a medical term that relates to the bones of the skull and face).

Knowing this about the vagus nerve, a referred pain toothache could also be indicative of lung cancer or, more mildly, sinusitis.

One study on facial pain as the first manifestation of lung cancer found that facial pain can, on rare occasions, be the presenting symptom of lung cancer.

In the case of sinusitis, “since the sinuses are located above the upper teeth, sinusitis or inflammation can be linked with a toothache,” says Hackney.

Don’t overthink it

Still, most of the time a toothache is simply that — a toothache. Referred pain can be difficult to pinpoint. Hackney says that if a toothache is coupled with symptoms such as sweating, lightheadedness, or respiratory difficulties, there’s a higher probability that it’s connected to a more serious condition.

“This is why when suffering from a toothache, don’t lose time and visit your dentist,” Hackney advises. “In the majority of cases, it means just toothache [and] healing it will help you to avoid more serious consequences.”

In the rarer cases, referred pain might just be your body’s way of helping you catch a serious health issue — and, like Niles, receive treatment before it gets worse.