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 periodically to monitor your reflux symptoms and treatments.

When Is pH Testing Needed?

Performed with a thin, plastic tube armed with a sensor, the pH test for acid reflux measures the amount of acid backing up into the esophagus. 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 (e.g., chest pain, asthma, hoarseness) need to be evaluated

Before doing any 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.

heartburn diagnosis
© Verywell, 2018 

Often, a GERD diagnosis is made based on symptoms alone (a clinical diagnosis.) If the diagnosis is uncertain, or if your symptoms are chronic and there's concerns about developing complications, further testing is recommended.

Testing is often done as well if you fail to respond to lifestyle changes and medications. At the current time, the most common test is an upper endoscopy. This is a procedure in which a tube is passed through your mouth and into your esophagus and stomach.

During the procedure, the healthcare practitioner can take biopsies of any abnormalities they find. If they don't find any, they may then recommend pH monitoring.

Less common tests include a barium swallow or esophageal manometry.

What to Expect

If your healthcare provider recommends an endoscopy, this will usually take place in the endoscopy suite at the hospital or in a free-standing endoscopy clinic. The procedure can be a little uncomfortable but is usually tolerated quite well.

Make sure to talk about medications such as:

  • Proton pump inhibitors (like Prilosec or another brand of omeprazole)
  • H2 blockers (such as ranitidine)
  • Antacids
  • Steroids
  • Calcium channel blockers
  • Nitrates

Sometimes a medication can be continued, but your healthcare provider needs to be aware of these as they may affect the pH test outcome.

Before Your Test

You will be instructed not to eat for four to six hours prior to your procedure. As noted, you should not take your regular acid reflux medications such as proton pump inhibitors or antacids prior to the test.


If you are having the pH test at the same time as an endoscopy, your healthcare provider will usually place an IV, give you a medication to relax you, and may also spray the back of your throat with a medication. When you are relaxed there are two ways in which your healthcare provider can place the probe in your body.

With a Tube

Your healthcare provider will insert a tubular probe through your nose and into your esophagus, stopping just above the lower esophageal sphincter. This may occur during endoscopy by clipping a pH monitoring device to the lining of the esophagus. The tube is then left in place for 24 hours. During that time, you are encouraged to engage in normal activities.

With a Capsule

Your healthcare provider requests that you swallow a disposable capsule—about the size of a large pill—that will travel down through your esophagus, stomach, and intestine. It wirelessly records data about symptoms and when you eat or lie down to a unit that you wear on your belt with a touch of a button.

Either method facilitates keeping a record of any suspected acid reflux issues, and other symptoms, such as coughing and wheezing. This can help the healthcare provider determine if acid reflux is related to unexplained asthma or other respiratory symptoms.

While you are having esophageal pH monitoring you will be instructed to eat regular meals and to resume your normal activities. You usually should not lie down, however, until you go to sleep for the night.


After your test, your throat may feel a little sore for a day or so. Sucking on lozenges or hard candy may be soothing. Later on, at your next healthcare provider's appointment, you should receive the results of your esophageal pH test.

pH Test Results

Most of the time people go home after the test and will have an appointment scheduled at which time they will hear about the results of the pH test.

Your pH monitoring may reveal that your pH is normal, in which case another type of testing may be recommended. If there is increased acid in your esophagus it could present as a few different conditions, ranging from esophagitis, to scarring (fibrosis), to Barrett's esophagus.

These issues are a consequence of increased acid exposure to the esophagus. At your visit, your healthcare provider will discuss what this means and whether further testing or treatment is needed.

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

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.

7 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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  2. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Diagnosis of GER & GERD.

  3. Cleveland Clinic. GERD: 24-Hour esophageal pH test: test details.

  4. 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

  5. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for GER & GERD.

  6. Plocek A, Gębora-Kowalska B, Białek J, Fendler W, Toporowska-Kowalska E. Esophageal impedance-pH monitoring and pharyngeal pH monitoring in the diagnosis of extraesophageal reflux in childrenGastroenterol Res Pract. 2019;2019:6271910. Published 2019 Mar 3. doi:10.1155/2019/6271910

  7. U.S. Department of the Interior, U.S. Geological Survey. pH scale.

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