While many people talk about acid reflux and heartburn synonymously, one is actually a cause, the other a symptom. Acid reflux occurs when foods or stomach acids travel up from one's stomach and into one's throat through the esophagus, causing the burning sensation known as heartburn. 

According to a National Institutes of Health report, about 60 million Americans experience heartburn at least once a month. Some research suggests that as many as 15 million experience it every day.

What is heartburn?

Heartburn is an uncomfortable feeling usually experienced or felt in one's throat or neck. "Typical features of heartburn include a burning sensation in the chest that may also involve the upper abdomen which usually occurs after eating, while lying down or bending over," says Michael Fredericson, MD, director of the Physical Medicine and Rehabilitation division of Stanford University.

Along with being painful and inconvenient, Fredericson says heartburn "can also cause complications like gastritis and stomach ulcers."

What does heartburn feel like? 

Though heartburn usually feels like the aforementioned burning sensation, some individuals experience it differently. "Some people describe heartburn as a sour taste rising from the stomach and into the throat," says Kyle Staller, MD, a gastroenterologist and the director of the Gastrointestinal Motility Laboratory at Mass General Hospital in Boston. Others experience it as pain behind the breastbone or as difficulty swallowing. Staller says the sensation may also be accompanied by a feeling of pressure or tightness in one's chest − so much so it's sometimes mistaken for a heart attack. "If you're unsure, it's always best to seek medical attention," he advises. 

Other elements of heartburn that can differ from person to person including where it feels like the burning sensation originates and how long it lasts. "Most people describe it as starting at the bottom of the rib cage and rising into the chest," explains Matthew Hoscheit, MD, a gastroenterologist at the Neurogastroenterology & Motility Center at Cleveland Clinic. Others don't notice it until it hits their throat or the back of their mouth.

Hoscheit says the sensation can last "as quickly as a couple minutes or as long as a few hours." 

What causes heartburn? 

Heartburn is a symptom of acid reflux that occurs "when a ring-like muscle at the bottom of your esophagus, (called the lower esophageal sphincter), doesn't close properly or relaxes when it shouldn't," explains Staller.

Though heartburn can happen to anyone, certain conditions and factors may make experiencing it more likely. These include pregnancy as a growing uterus can crowd out one's stomach, obesity as weight increases pressure on one's abdomen, medications like ibuprofen or naproxen, and "certain foods or drinks such as carbonated drinks, chocolate, citrus fruits, acidic foods, fried foods, spicy foods, alcohol and caffeine," says Heather Viola, DO, a primary care physician at Mount Sinai Doctors-Ansonia. 

Heartburn can often be avoided or alleviated by steering clear of any foods that are noticed to cause acid reflux, by taking steps to lose weight if one is medically overweight, by elevating one's head when lying down, and by taking common medications such as Alka-Seltzer. "However, if you experience frequent or severe heartburn, or if it doesn't improve with over-the-counter remedies," advises Staller, "it's essential to consult a healthcare professional for a proper evaluation and guidance on managing your symptoms." 

More:Alka-Seltzer is the most commonly recommended medication for heartburn. Here's why.