Esophageal pH Test for Acid Reflux: What to Expect

This procedure is often done when GERD symptoms are present

The pH test for acid reflux (gastroesophageal reflux disease or GERD) provides several measures of how stomach acid behaves in your esophagus, including:

  • How often it enters
  • How long it stays
  • How well it's cleared out

Your healthcare provider may order this test to confirm a diagnosis or to periodically monitor your reflux symptoms and treatments.

This article explains why you may need the test and the ways the test is conducted. It also explains what you can expect to learn from the test results.

Purpose of Test

The pH test for acid reflux measures the amount of acid backing up into the esophagus. Performed with a thin, plastic tube armed with a sensor, this procedure is often done when:

  • You have GERD symptoms, but an endoscopy exam doesn't detect any evidence of reflux disease
  • The standard treatment of a twice-daily dose of proton pump inhibitor (PPI) medication doesn't help
  • Less common symptoms of GERD (such as chest pain, nocturnal cough, asthma, hoarseness) need to be evaluated

Before testing, your healthcare provider will ask you about your symptoms of GERD. These include:

  • Heartburn
  • Nausea or abdominal pain
  • Difficulty swallowing
  • Chronic cough

Your healthcare provider will also ask you about your risk factors for GERD, including whether you have a hiatal hernia, smoke, take medications, or eat foods that could predispose you to reflux.

Diagnosing GERD

Often, a GERD diagnosis is made based on symptoms alone (a clinical diagnosis.)

If the diagnosis is uncertain or your symptoms are chronic, and there are concerns about complications, further testing is recommended. The standard test is an upper endoscopy in which a tube is passed through your mouth and into your esophagus and stomach.

Sometimes this test shows no evidence of abnormality to explain your symptoms. That's when your healthcare provider may recommend pH monitoring.

heartburn diagnosis
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Before Your Test

You will be instructed not to eat after midnight before your procedure. Because some medications can affect the test results, you may be told to avoid taking some prescription or over-the-counter medications. Discuss this with your healthcare provider.

Medications that are sometimes paused include:

During the Test

To conduct a pH test, your healthcare provider must place a monitor into your esophagus to track acid levels. There are two types of monitors that are used for this test: a catheter and a wireless capsule.

Catheter Test

The catheter is placed using a scope. Your healthcare provider will usually place an IV and give you medication to relax you. They may also spray the back of your throat with medication.

A tube with a sensor on its end is inserted through your mouth or nose and into your esophagus. The sensor is then attached to the lining of the esophagus, and the tube is removed. the sensor will wirelessly send data to a monitor that you can wear around your waist or shoulder.

Capsule Test

For this procedure, you will need to swallow a disposable capsule—about the size of a large pill. This will travel down through your esophagus, stomach, and intestine. It wirelessly records data about your symptoms and when you eat or lie down.

Both types of sensors will gather information about your symptoms. You are encouraged to engage in everyday activities and keep a diary of what you eat and any GERD episodes or suspected acid reflux issues and symptoms, such as coughing and wheezing. This can help your healthcare provider determine if acid reflux is related to unexplained asthma or other respiratory symptoms.

After the Test 

After your monitor is placed or swallowed, your throat may feel slightly sore for a day. Sucking on lozenges or hard candy may help soothe this discomfort. The sensor itself should not cause any pain or be detectable. It will pass through your digestive tract within days and be excreted without problems.

Your healthcare provider will review the data gathered by the sensor and your diary entries. You will need to schedule a follow-up appointment to review these results.

Interpreting Results

Typically, the pH level in the esophagus should be close to 7.0. Esophageal pH tests look for intervals in which pH reaches lower levels, such as below 4.0, which is highly acidic and means that you're experiencing a surge of stomach acid.

While abnormal results may indicate GERD, increased stomach acid may also be due to conditions such as:

If your pH monitoring results reveal that your pH is normal, but you're still experiencing GERD symptoms, another type of testing may be recommended. These tests may include a barium swallow or an upper endoscopy (esophagogastroduodenoscopy).

Depending on your results, your healthcare provider may recommend lifestyle changes and medications to ease your symptoms and prevent complications.


The esophageal pH test checks how much stomach acid enters your esophagus and how long it remains. It's an important test to diagnose or monitor GERD. It can be used to help you manage your symptoms or to identify other possible health conditions that could be causing GERD-like problems.

A Word From Verywell

Chest pain and symptoms such as coughing or wheezing are often signs of GERD, but they can also be related to other conditions. To ensure you have the right diagnosis and to find clues to how you can best manage your symptoms if they are related to GERD, an esophageal pH test is worth it. It can be a bit uncomfortable and inconvenient for a day, but the information gathered can help you enjoy a better quality of life and peace of mind.

Frequently Asked Questions

  • Is acid reflux a pH imbalance?

    A pH imbalance can lead to acid reflux and gastroesophogeal reflux disease (GERD). Higher acidity is linked to more severe symptoms.

  • Is higher pH better for acid reflux?

    Yes, a high pH means that something is less acidic and more alkaline (basic). A lower pH (more acidic) can increase symptoms of reflux and GERD.

  • What is the best test for GERD?

    An upper gastrointestinal (GI) endoscopy is usually the preferred diagnostic test for GERD and its complications. Esophageal pH monitoring is the most accurate way to tell whether there's stomach acid in your esophagus.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  6. Wang RH. From reflux esophagitis to Barrett's esophagus and esophageal adenocarcinoma. World J Gastroenterol. 2015;21(17):5210-9. doi:10.3748/wjg.v21.i17.5210

  7. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for GER & GERD.

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By Sharon Gillson
 Sharon Gillson is a writer living with and covering GERD and other digestive issues.