Everyone experiences "heartburn" on occassion, from overeating, too much hot sauce, etc..
The serious variety is caused from "acid reflux syndrome of the esophagus", which may or may not be linked to a hiatal hernia, which would allow food to "back up" into the esophagus.
The constant discomfort can lead to more serious problems.
The most serious of all is cancer of the esophagus, in which the repeated and long-term acid reflux creates ulcers and deteriorates the lining of the esophagus.
Most cases are seen late in life, and many also involve heavy intake of alcohol and tobacco use.
More common will be such symptoms as dental erosion caused from regurgitating stomach acid while asleep.
Over the counter meds should be used, such as Zantac, Prilosec, etc., which block stomach acid production, are relatively harmless, and last an entire day.