The terms Acid Reflux, GERD, and heartburn are often used interchangeably but they are not all exactly the same thing. There are some subtle differences between the terms that could make a big difference.
Heartburn, despite its name, has nothing to do with the heart, although severe heartburn can feel like a heart attack. Instead, it describes the burning sensation felt in the chest behind the breastbone in the esophagus.
Heartburn is often a symptom of acid reflux but this is certainly not the only cause so you can see why the one should not be automatically used as a substitute for the other. Where acid reflux is the culprit, the contents of the stomach flow the wrong way back into the esophagus through the LES (lower esophageal sphincter). As these contents are by nature very acidic, they chemically burn the esophageal tissue and the resultant inflammation is felt as heartburn.
Heartburn, however, can also be a symptom of esophagitis, defined as any irritation or inflammation in the esophagus.
Esophagitis can be caused by allergies, infections (e.g. Candida), chemotherapy, radiation and certain medications like such as bisphosphonates (especially Fosamax), NSAIDs (non-steroidal anti-inflammatory drugs like ibuprofen), aspirin, antibiotics like tetracycline, and supplements like Ferrous sulfate.
All of these directly or indirectly irritate the lining of the esophagus. Tetracycline and ferrous sulfate are extremely acidic when combined with saliva and can result in an acid burn similar to that from gastric acid. Of course here the acid is coming from the opposite direction, top down instead of bottom up.
While heartburn is the subjective symptom, acid reflux refers to the mechanism that could trigger it but not everyone with reflux experiences heartburn.
Acid reflux occurs when the valve, which should act as the one way gateway between the stomach and the esophagus, malfunctions. This allows acidic gastric fluid to leak up into the esophagus, where it has no business being. The esophagus has no protective barrier against stomach acid so it reacts to the chemical insult through inflammation and pain and you often, but not always, get the sensation of heartburn.
A number of things can impact the function of the LES. Pregnancy, stomach distension from overeating, obesity and hiatal hernia can all put pressure on the abdomen and affect the way the LES functions.
Some people have ‘silent reflux’, which is acid reflux minus the heartburn. Here the acidic contents reflux right up into the throat area, causing throat swelling and irritation, hoarseness, coughing, regurgitation, an acrid taste in the mouth, difficulty swallowing, a persistent need to clear the throat and a feeling of something obstructing the throat.
Acid in the throat can even land up in the lungs, causing respiratory problems and wheezing.
GERD stands for gastroesophageal reflux disease and is the name given to chronic or persistent acid reflux accompanied by esophageal inflammation.
All of the various symptoms of acid reflux obviously apply to GERD but there can be some extra ones like erosion of tooth enamel from the continuous acid bath and changes to the cells lining the bottom of the esophagus. Esophageal bleeding, ulcers, and scarring would also indicate chronic acid reflux.
In short, GERD is a disease, heartburn is the most common symptom and acid reflux is the deviation from the normal function of the LES leading to both.