You have the typical acid reflux symptom: heartburn. You have the typical indigestion symptoms: a sour stomach, pain in the upper abdomen or chest. You're regurgitating food and bitter liquid. You're producing excessive saliva. All signs point to acid reflux. But when you visit your doctor and undergo tests, the tests come up negative. You're confused. How can this be?

This first thing you need to understand is how an acid reflux diagnosis works. If you have acid reflux symptoms, your doctor may begin by suggesting certain lifestyle changes, like losing weight, eliminating fattening foods, or changing how and when you sleep. You may also be directed to over-the-counter medicines (OTC), like antacids (think: Maalox, Mylanta, Rolaids).[1] If these changes and drugs take care of the problem, you may just be one of 60 million Americans suffering from common heartburn.[2]

But if the symptoms persist, the doctor may order a diagnostic test to see if you have gastroesophageal disease (GERD). Mostly, these are meant for people with strong symptoms, ones that are frequent, are severe, and are not controlled with modification in diet and lifestyle (including OTC meds). According to the American College of Gastroenterology, this leads to EGD and Esophageal Manometry and pH tests.[3] It seems that anyone who would undergo such advanced testing would certainly have some form of GERD.

However, this is not necessarily the case. Given the complications of our digestive system, there are various ways for us to demonstrate symptoms and incur diseases. More so, there are many different digestive diseases; the National Institute of Diabetes and Digestive and Kidney Diseases lists several dozen of them, along with symptoms, cures, ways of diagnosis, and need-to-know basics.[4] And while each disease is unique, the symptoms of each tend to overlap.

Remember indigestion? Well, this disease is closely related to GERD. Its symptoms include feeling full during a meal, feeling uncomfortable after a meal, and a burning or pain in the upper abdomen, and it can even be caused by GERD. More so, it can be diagnosed and treated similarly to GERD (with basic diet and lifestyle modifications). Yet it is not the same as heartburn (which is simply the main symptom of acid reflux), and thus it is not the same as acid reflux.

In fact, this is true for many digestive diseases (like Irritable Bowel Syndrome, which, like acid reflux, is associated with large meals, chocolate, alcohol, caffeine, and stress). All it means is that if you test negative for acid reflux, you may have a different-and potentially less serious-problem.