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Esophageal pH Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Esophageal pH Test

An esophageal pH test measures the frequency and duration of stomach acid entering the esophagus to help diagnose acid reflux or GERD.

Overview

An esophageal pH test measures how often stomach acid enters your esophagus—the muscular tube that carries food and liquids from your mouth to your stomach—and how long the acid stays there. The test involves placing a catheter or a special device called a pH probe into your esophagus to measure your acid level (pH level) for 24 to 96 hours.

The test helps identify the following conditions:

  • Acid reflux (gastroesophageal reflux or GER): Occurs when stomach acid flows back into the esophagus, often causing a burning sensation in the chest or neck known as heartburn.
  • GERD (gastroesophageal reflux disease): A more serious, long-lasting form of reflux that can cause repeated symptoms and lead to complications if left untreated.

What is it used for?

The test is primarily used to diagnose acid reflux or GERD. It may also be used to determine if a current treatment plan for GERD is effective.

Why do I need an esophageal pH test?

You may require this test if you experience symptoms of acid reflux, including:

  • Heartburn
  • Regurgitation (swallowed food coming back into your mouth)
  • Trouble swallowing
  • Feeling like there is a lump in your throat
  • Sore throat
  • Cough
  • Frequent burping

What happens during an esophageal pH test?

The test is performed using either a catheter or a wireless pH probe.

Catheter Test

  • A provider inserts a small, thin tube through your nose or mouth into your esophagus.
  • The tube is connected to a monitor worn around your waist or shoulder that records acid levels for 24 hours.
  • You must keep a diary of your symptoms and food intake during this time.
  • The tube and monitor are removed by your provider the following day.

Wireless Test (pH Probe Study)

  • A provider attaches a small, capsule-like pH probe to the lining of your esophagus during an upper endoscopy.
  • You will receive medicine to help you relax and block pain during the procedure.
  • The probe transmits data to a device worn on your wrist or belt for 48 to 96 hours.
  • You must keep a diary of symptoms and food intake during the monitoring period.
  • The probe typically leaves your body through a bowel movement within 4 to 10 days.

Preparation and Risks

Preparation:

  • Fast (no food or drink) for four to six hours before the procedure.
  • Consult your provider regarding stopping certain medications, such as antacids, which may need to be paused for 24 hours to two weeks prior.
  • Inform your provider if you have a pacemaker, an implantable heart defibrillator, a history of esophageal problems, or bleeding disorders.

Risks:

  • Catheter test: Mild discomfort in the nose or throat, gagging during insertion, or rarely, a nosebleed.
  • Wireless test: Sore throat from the endoscope or, in very rare cases, a tear in the esophageal lining.

What do the results mean?

High acid levels may indicate:

  • Acid reflux or GERD
  • Esophagitis (swelling or inflammation of the esophagus)
  • Stricture (narrowing of the esophagus)
  • Barrett's esophagus (damage to the esophageal lining that may increase cancer risk)

Management

If diagnosed, symptoms may be managed through diet (limiting fatty/spicy foods, citrus, tomatoes, and alcohol) and lifestyle changes (eating smaller meals, quitting smoking, waiting before lying down, and weight loss). Over-the-counter medications or prescription treatments may be recommended if symptoms persist.

Frequently Asked Questions

The procedure itself is minimally invasive and usually not painful. Inserting the catheter through the nose may cause some mild discomfort or a gagging sensation, but this typically subsides quickly. The main challenge is the discomfort of having a tube in your nose for 24 to 96 hours. You may feel a slight pressure or irritation, and you should avoid bending over or lying flat immediately after eating to reduce reflux. Wireless capsule tests are often preferred by patients because they do not require a nasal tube, though the capsule passes through the digestive tract and is excreted in stool.
Yes, you are generally encouraged to eat and drink as you normally would to provide an accurate picture of your daily acid exposure. However, you should avoid foods and beverages that are known to trigger your specific symptoms, such as alcohol, caffeine, or spicy foods, unless your doctor instructs otherwise. You must keep a detailed diary of what you eat, when you eat, and any symptoms you experience (like heartburn or regurgitation) so the doctor can correlate the pH data with your symptoms.
Results are typically available within a few days to a week after the monitoring period is complete. The data from the monitor or capsule is downloaded and analyzed by a specialist who looks for patterns in acid exposure and correlates them with your symptom diary. Your healthcare provider will discuss the results with you and explain what they mean for your diagnosis and treatment plan.
If you notice the catheter has come out of your nose or if the wireless capsule is not functioning as expected, contact your healthcare provider immediately. Do not attempt to reinsert the catheter yourself. In most cases, the test will need to be repeated to ensure accurate data collection. It is important to keep the catheter secure and avoid activities that might pull on it, such as vigorous exercise or heavy lifting.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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