Heartburn

Struggling with heartburn? Here’s what you need to know to find relief.

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What is heartburn?

Heartburn is a burning pain in your chest. This pain is caused by stomach acid rising from your stomach into your oesophagus (the pipe that takes food from your mouth to your stomach).

This can cause:

- Burning pain in the middle of your chest

- Pain which is worse when you bend over or lie down

- Burning pain that radiates into your back

By learning more about the causes of, tests for, and treatment for heartburn, you can understand it better and make informed decisions to get back on track.

Why does heartburn happen?

There are several possible causes of heartburn, and it’s important to find out what’s causing yours.

Here are the main causes of heartburn:

Gastroesophageal reflux disease (GORD)
Hiatus hernia, when part of your stomach moves up into your chest
Surgery you’ve had in the past (especially bariatric surgery)
Certain foods and drinks, such as alcohol, coffee, chocolate, and fatty or spicy foods
Being overweight
Smoking
Pregnancy
Stress or anxiety
Medication, such as anti-inflammatory painkillers
Overgrowth of bacteria in your small intestine (this is called SIBO)

Diagnosing heartburn

Diagnostic testing allows us to pinpoint the exact cause so we can recommend the right solution.

Oesophageal manometry, 24-hour pH, malabsorption breath tests, SIBO & gastric emptying

At the Functional Gut Clinic, we use the following highly accurate and trusted diagnostic tools, to identify the underlying cause of your heartburn:

Oesophageal manometry – which measures the function of your oesophagus (food pipe)

24-hour pH impedance monitoring – which looks at whether you have any reflux

Carbohydrate malabsorption breath test – which finds out if you have certain food intolerances (lactose or fructose)

Small intestinal bacterial overgrowth (SIBO) breath test – which finds out if you have an overgrowth of bacteria in your small intestine (called SIBO)

Gastric emptying test – which measures how quickly food leaves your stomach

Find out more and book your test

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Lower Esophageal Sphincter Explained

Education| Reflux

February 17, 2025•5 min read

If you’ve ever had a problem with acid reflux, it’s likely there might be an issue with your lower esophageal sphincter. It’s located between the esophagus and the stomach, preventing food and acid from getting out. The sphincter is controlled by involuntary muscles which move and contract without you consciously activating them.

Understanding the lower esophageal sphincter, or LES, is crucial to preventing and treating problems associated with reflux and other similar conditions.

In this guide:

What is the Lower Esophageal Sphincter?

How Does the Lower Esophageal Sphincter Work

Potential Problems

Diagnosis and Testing

Treating a Weak Lower Esophageal Sphincter

Summary

What is the Lower Esophageal Sphincter?

The lower esophageal sphincter (LES) is a muscular valve controlling the bottom end of the esophagus. That’s the food pipe that carries undigested material from your throat to the stomach.

The LES is also known as the gastroesophageal sphincter. It’s a term that refers to the junction between the two structures, as “gastro” means stomach. Due to its close proximity to the heart, acid reflux in this region can be confused with cardiac pain. That’s why the discomfort is called heartburn. However, the two organs are not connected.

There’s an upper esophageal sphincter, called the pharyngoesophageal sphincter, that controls the entrance. It prevents air from entering the esophagus when people are talking. Unlike its lower counterpart, the upper sphincter has some conscious control, whereas the LES opens and closes involuntarily.

How Does the Lower Esophageal Sphincter Work

Usually, the UES and LES work in tandem with muscles in your food pipe that cause rhythmic contractions that move the food downwards. This is known as peristalsis. The sphincters are controlled by nervous signals that determine when the sphincter can open and close.

As mentioned, the upper sphincter has some input from the person whereas the lower sphincter acts independently. The lower sphincter, like any muscles, can also become weak. If this happens, even if a signal is given, the LES might not have the power to stay closed. If pressure builds in the stomach, then reflux can occur, leading to acid and food in the esophagus.

People often notice a burning sensation. There may even be an acidic taste, sore throat, and coughing, as the acid irritates your voice box.

Potential Problems

The lower esophageal sphincter can face several potential issues. Most commonly, reflux happens when food moves from the stomach back up into the esophagus and even the throat. This occurs when then LES fails to close or when pressure on the stomach forces it open. Such regurgitation can be exacerbated if the person has a hiatus hernia. In this condition, the LES and part of the stomach sit above the diaphragm in the chest and not the abdomen.

Other potential issues include:

Achalasia occurs when the LES fails to relax. The food becomes trapped open the LES and cannot enter the stomach. It can create a very strange feeling of discomfort. The condition is diagnosed with an esophageal manometry test.
Esophagitis is the inflammation of the esophagus. Inflammation can result from repeated acid attacks. If this continues to happen, it can change the cells, increasing the risk of cancer. Alongside esophagitis, esophageal tears can also occur. However, such injuries are relatively rare.
Dysphagia is a dysfunction of swallowing. A person feels pain when swallowing, often coughing or gagging. There may not be any physical barrier to swallowing, but the pain prevents them from doing so.

Diagnosis and Testing

If a doctor recognizes the symptoms of an LES problem, they may recommend diagnostic testing. Often people are prescribed anti-acid drugs, like proton pump inhibitors (PPIs) without any testing. However, if there’s a chance something serious is going on, your doctor will want to check.

The most common tests include:

Barium esophagram. Also known as a barium swallow, the procedure involves taking an X-ray after swallowing barium. This fluid appears opaque on an X-ray, allowing doctors to visualize any abnormalities.
Upper endoscopy. This procedure involves inserting a camera via the nose or throat to visualize the esophagus and stomach. Some procedures even take a look at the duodenum – the bit after the stomach.
Esophageal pH monitoring. The test is the gold standard for confirming gastroesophageal reflux disease (GERD). It measures the acidity level around the LES for 24 hours.
Esophageal manometry. Like the other tests, it can diagnose GERD, as well as achalasia, hypertensive LES, and esophageal spasm. It measures the pressure differences along the entire length of the esophagus or sometimes just around the lower sphincter.

The Functional Gut Clinic offers several types of gastric reflux tests. This includes 24-hour reflux testing to confirm if you’ve got any acid leakage from your stomach and the severity of the problem. Alongside 24-hour testing, we offer esophageal manometry to confirm the underlying problems. It’s the most accurate testing combination to diagnose what’s going on.

Capsule Endoscopy in Gastrointestinal Disease can also be used to investigate certain conditions of the small intestine, although it's not typically used for diagnosing LES problems directly.

Treating a Weak Lower Esophageal Sphincter

Treating a weak LES isn’t as simple as hitting the gym. While it’s a muscle, it cannot be trained by conscious control. That leaves several indirect measures.

The most common approaches focus on the acid reflux rather than the weak LES. You could take chewable antacids to counteract the acid, or even medications like PPIs to prevent acid production. Lifestyle changes are also effective at reducing stomach acid levels. Fatty, sugary foods increase acid production, while eating before bed can cause late night reflux symptoms.

Other potential treatments include:

Botox injections
LES dilation
Surgery

Summary

The lower esophageal sphincter, also known as the gastroesophageal sphincter, is your body's natural barrier against acid reflux, sitting between your esophagus and stomach. Getting to know how it works and what can go wrong is key to managing and treating conditions like reflux. Whether through medication or lifestyle changes, understanding this muscle's function can help keep your digestive discomfort at bay, with tests like barium swallows aiding in pinpointing issues.

The Functional Gut Clinic

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Heartburn is a burning pain in your chest.

Heartburn is often experienced after eating and can last anywhere from a few minutes to several hours. The stomach releases more acid after eating certain foods, including spicy dishes, fatty foods, citrus fruits, tomato-based products, garlic, and caffeinated drinks. The more acid that is produced, the greater the risk of heartburn.

Other factors include obesity, smoking, stress, pregnancy, and eating too close to bedtime.

What are the symptoms of heartburn?

Heartburn primarily causes an uncomfortable or burning sensation in the middle of your chest. You may also experience:

A burning sensation in your throat
A strong acidic or sour taste in your mouth
Difficulty swallowing (dysphagia)
A feeling of pressure or pain behind your breastbone
Repeated coughing
Hoarse voice

In addition to these symptoms, the pain from the acid can get worse when lying down or bending over. This is because the acid flows out of the stomach and into the oesophagus. Whenever you lie down, you increase the risk of heartburn-related symptoms.

Constant heartburn is a sign of a severe underlying condition. Most people experience heartburn in episodic attacks – usually after consuming certain foods. If the heartburn is persistent, it’s crucial to speak to a medical professional. You can also consider organising a test via The Functional Gut Clinic (see below).

What causes heartburn?

Heartburn occurs when the contents of the stomach enter the oesophagus (the food pipe connecting your stomach to your throat). Usually, the stomach contents are prevented from going back into the oesophagus by a juncture called the lower oesophageal sphincter. However, in some people, this sphincter doesn’t function properly.

Heartburn is a symptom of gastroesophageal reflux disease (GORD). GORD simply refers to the backflow of acid from the stomach into the oesophagus. GORD is the condition; heartburn is the symptom.

Several factors increase the risk of heartburn. The causes of heartburn and GORD either increase acid production within the stomach or affect the functioning of the lower oesophageal sphincter. These include:

Hiatal hernia. A hiatus hernia involves a part of your upper stomach penetrating through the diaphragm (the layer of muscle separating your chest from your stomach). This usually occurs due to a weakness or tear.
Pregnancy. If you become pregnant, the increased pressure during the third trimester (and sometimes earlier) forces the stomach contents backwards, causing heartburn.
Surgery. Previous surgery, especially bariatric surgery, increases the risk of not only heartburn but also a hiatus hernia.
Smoking. Smoking is closely linked to heartburn and GORD. People who quit smoking notice a significant reduction in heartburn symptoms.

Overweight or obesity. Being overweight or obese is a major risk factor for GORD. This is likely due to the increased pressure in the stomach alongside a diet high in fatty, processed foods.
Medications. Certain medications, such as anti-inflammatory painkillers (e.g., ibuprofen or aspirin), sedatives, and blood pressure medications, can increase your risk of heartburn.
Stress or anxiety. An increase in stress or anxiety can increase acid production in some people, leading to heartburn. It’s often accompanied by another factor.
Small intestine bacterial overgrowth (SIBO). Excessive bacterial growth in the small intestine leads to increased abdominal pressure and subsequent acid reflux, which can cause heartburn. Managing SIBO often reduces these symptoms.

Foods to avoid

Acid production is a normal part of the stomach’s function. The acid helps digest food. Certain foods require more acid to digest, triggering an increased production in the stomach.

For most people, this isn’t an issue as the acid flows into the small intestine. However, if you struggle with heartburn and GORD, then it’s sensible to limit or avoid certain foods. These include:

Citrus fruits (like oranges and grapefruits)
Tomatoes and tomato-based products
Spicy foods
Garlic and onions
Chocolate
Mint
Fatty or fried foods
Caffeinated beverages (such as coffee and tea)
Carbonated drinks
Alcohol

It’s not just the food. Eating an excessively large meal, wearing tight clothes, and lying down soon after eating can increase the risk of heartburn. If you’re experiencing persistent heartburn, it’s often linked to diet rather than another factor.

Is heartburn the same as GORD?

No. Heartburn specifically refers to the burning sensation in the chest. GORD is the underlying condition involving the backflow of acid. Heartburn is a symptom of GORD. Acid reflux is sometimes used as shorthand for GORD – however, not every attack of acid reflux is an example of GORD.

Acid reflux refers to any episode of acid backflowing into the oesophagus. If the episodes occur two or more times a week, it is diagnostic for GORD. Most people experience acid reflux episodes occasionally. This can increase in frequency as acid reflux progresses to GORD. You should speak to a doctor if you notice this change.

Does acid reflux always cause heartburn?

Heartburn is always caused by the backflow of acid into the oesophagus. Several other conditions can create a similar sensation. For example:

Oesophageal ulcers. Ulcers occur due to erosion of the oesophageal lining. Often associated with acid reflux or overusing anti-inflammatory medications.
Oesophagitis. Severe inflammation of the oesophagus is closely linked to GORD. However, it can also be caused by medications and infections. An allergic condition known as eosinophilic oesophagitis can also cause heartburn.
Functional heartburn. Unlike the other conditions, this isn’t a problem with your oesophagus or stomach. It’s caused by a disorder of the gut-brain connection. It involves the same heartburn symptoms but without any signs of acid reflux or inflammation. It’s connected to overactive nerves.

How long does heartburn last?

Heartburn is not a permanent condition. It lasts as long as the acid is present to irritate the oesophagus and throat. Most people experience heartburn and GORD for between a few minutes to several hours. The timespan often depends on the underlying cause. For example, if your heartburn is due to your diet, it might go away within a few minutes. In contrast, if you have a hiatus hernia, the heartburn might persist for much longer, even after standing up.

Constant heartburn is a rare symptom. It’s a concerning sign, as the acid can continue to damage your oesophagus. If you’re constantly feeling heartburn (or using lots of antacids), then it’s critical to speak to a doctor.

Is heartburn serious?

Most cases of heartburn aren’t serious. It’s common to experience heartburn after a large meal or eating certain foods. However, if the heartburn becomes repeated or constant, it can cause long-term damage. Usually, the damage caused by acid reflux heals like any injury. If it happens regularly, then the oesophagus lining can become permanently injured.

Potential long-term complications include:

Oesophageal strictures. The lining of the oesophagus becomes replaced with scar tissue due to repeated inflammation. This scar tissue causes a narrowing of the oesophagus (stricture), which prevents food from getting through.
Intestinal metaplasia. The tissue lining of the oesophagus undergoes a change to look more like the lining of your intestines, protecting it from damage. It is called Barrett’s oesophagus and is a precancerous condition.
Oesophageal cancer. Cancer is a rare complication of GORD and heartburn. It occurs due to persistent inflammation and cellular changes. The longer your heartburn persists, the greater the risk of cancer.

Heartburn and GORD can also indicate problems in your stomach. For example, excess acid production can lead to gastritis (stomach inflammation) and stomach ulcers. It may also aggravate preexisting conditions such as asthma.

How do we diagnose the causes of heartburn?

The following tests may be used to diagnose what is causing your heartburn:

Oesophageal manometry – which measures the function of your oesophagus (food pipe)
24-hour pH impedance monitoring – which looks at whether you have any reflux
Carbohydrate malabsorption breath test – which finds out if you have certain food intolerances (lactose or fructose)
Small intestinal bacterial overgrowth (SIBO) breath test – which finds out if you have an overgrowth of bacteria in your small intestine (called SIBO)
Gastric emptying test – which measures how quickly food leaves your stomach
The following tests may be used to diagnose what is causing your heartburn:
Oesophageal manometry – which measures the function of your oesophagus (food pipe)
24-hour pH impedance monitoring – which looks at whether you have any reflux
Carbohydrate malabsorption breath test – which finds out if you have certain food intolerances (lactose or fructose)
Small intestinal bacterial overgrowth (SIBO) breath test – which finds out if you have an overgrowth of bacteria in your small intestine (called SIBO)
Gastric emptying test – which measures how quickly food leaves your stomach

Heartburn treatment

Lifestyle changes

Most people who experience occasional heartburn symptoms can benefit from lifestyle changes. This involves limiting exposure to potential triggers. You might want to try:

Avoiding trigger foods, such as fatty foods or caffeinated beverages
Eating smaller meals
Avoiding tight clothing
Avoiding lying down immediately after eating
Quitting smoking and alcohol consumption.

Often, people find that small changes to their diet can stop or reduce episodes of heartburn. If the heartburn continues, it’s usually a sign that something else is going on. It’s crucial to get to the bottom of your symptoms; otherwise, they will persist.

Medication

As heartburn is caused by acid, neutralising this acid relieves symptoms. The primary treatment for heartburn is an over-the-counter (OTC) antacid, such as Gaviscon or Alka-Seltzer. These medications provide immediate relief from your symptoms – perfect for tackling a sudden acid reflux attack. If you experience constant heartburn, it’s sensible to carry antacids with you. However, excessive use of antacids can cause other problems.

Your doctor may prescribe medications that prevent acid production. This includes:

Proton Pump Inhibitors (PPIs). These medications reduce stomach acid production by blocking the enzyme in the stomach lining that produces acid. Common examples include omeprazole, esomeprazole, and pantoprazole. PPIs are used to treat GORD by allowing the oesophagus to heal and preventing further damage.
H2 Receptor Antagonists. These drugs work by blocking H2 receptors on stomach cells that signal the production of acid. This results in decreased stomach acid output. Examples include ranitidine, famotidine, and cimetidine. They are effective in relieving GORD symptoms and are generally used for milder cases.

Surgery

In the majority of cases, lifestyle changes and medication are enough to prevent heartburn symptoms. If GORD doesn’t respond to medication, surgery might be a potential option. This can repair a hiatus hernia, strengthening the lower oesophageal sphincter and permanently preventing the backflow of acid.

Procedures include:

Nissen fundoplication. This procedure tightens the junction between the stomach and the oesophagus.
Transoral incisionless fundoplication. A similar procedure performed non-surgically using an endoscope.
LINX device. A tiny ring of magnets is placed around the junction between the stomach and oesophagus to prevent reflux. It’s a type of minimally invasive surgery.

When should you seek medical care for heartburn?

Heartburn is extremely uncomfortable. However, most cases are relatively mild and treatable with antacids. Speak to a medical professional if:

You experience heartburn more than once a week
You have other associated symptoms
You have difficulty swallowing
Your heartburn persists despite treatment
You’re over the age of 60
You have a tight or squeezing chest pain
You cough up blood

Remember, occasional heartburn is relatively normal. But if you have constant heartburn, it’s crucial to get tested. The Functional Gut Clinic is highly experienced in diagnosing acid reflux. We’ll organise your test and provide advice on what to do next.

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