What Is LPR? The Reflux Most Doctors Miss

If you've spent years dealing with a chronic cough, a sensation of something stuck in your throat, a hoarse voice that won't go away, or constant throat clearing, you've probably been to multiple doctors. ENT. Primary care. Maybe an allergist. Probably a gastroenterologist.

You may have been put on an inhaler that didn't help. Tested for allergies that came back negative. Scoped for acid damage that didn't show. Maybe prescribed a PPI that worked a little but didn't really solve the problem.

There's a reasonable chance the issue is laryngopharyngeal reflux. LPR. Sometimes called silent reflux. And it's one of the most underdiagnosed conditions in clinical practice.

This article covers what LPR actually is, why it's so commonly missed, why standard reflux treatments often don't work for it, and what the research says about approaches that do.

What LPR Is, and Why It's Different From GERD

GERD is what most people think of when they hear "reflux." Stomach acid escapes upward through the lower esophageal sphincter and irritates the esophagus. The classic symptoms are heartburn, regurgitation, chest discomfort. GERD lives in the chest.

LPR is something different. In LPR, stomach contents escape past both the lower esophageal sphincter AND the upper esophageal sphincter, reaching the throat, voice box (larynx), and sometimes the sinuses. It lives above the collarbone.

The symptom pattern is completely different from GERD:

Chronic throat clearing. Not occasional. All day, every day. You stop noticing you're doing it until someone else points it out.

Persistent cough. Often worse at night or first thing in the morning. Not associated with a cold or allergies. Doesn't respond to cough suppressants.

Hoarseness. Your voice sounds tired or raspy by the end of the day. Singers and public speakers notice this first.

Globus sensation. The feeling that something is stuck in your throat. Swallowing doesn't clear it. Drinking water helps temporarily.

Post-nasal drip. Often misdiagnosed as allergies or sinus issues. Doesn't respond to antihistamines.

Sore throat that won't go away. Especially in the morning. No infection, no fever.

Sour or bitter taste in the mouth. Especially upon waking.

Trouble swallowing. Mild dysphagia, often described as food getting stuck briefly.

Here's the part that catches most patients off guard: most LPR patients don't have classic heartburn. Koufman's seminal 1991 study in Laryngoscope, which established LPR as a distinct clinical entity from 225 patients with ambulatory 24-hour pH monitoring, showed that fewer than half of LPR patients had typical GERD symptoms. Their reflux events happened more during the day, in upright positions, and in shorter bursts that didn't generate the classic chest burn.

This is why LPR is so often missed. Patients don't have the textbook symptoms. Doctors look for heartburn. Patients say no. The diagnostic conversation goes elsewhere.

Why LPR Is So Commonly Missed

There are four structural reasons LPR slips through the diagnostic cracks.

1. Standard reflux tests often come back normal.

Upper endoscopy looks for visible damage in the esophagus from acid exposure. Many LPR patients have minimal or no esophageal damage because the reflux events are brief and travel quickly past the esophagus on the way up to the throat. The throat tissue takes the damage, but endoscopy doesn't look there in the same way.

24-hour pH monitoring detects acid in the esophagus, but LPR events are often less acidic, less frequent, and don't accumulate the way GERD events do. pH monitoring can miss them.

The result: patients with significant LPR symptoms get told their reflux tests are "normal," and the conversation moves on to other diagnoses.

2. The specialty split.

GERD lives with gastroenterologists. LPR lives somewhere between gastroenterology and ENT, and neither specialty fully owns it. GIs often treat LPR symptoms with the same PPI protocol they use for GERD (which, as we'll cover, doesn't address the actual mechanism). ENTs see the laryngeal damage but often can't address the upstream cause. Patients bounce between specialties without a clear plan.

3. Symptoms mimic many other conditions.

Chronic cough can be asthma, allergies, post-viral irritation, ACE inhibitor side effects, or LPR. Globus sensation can be anxiety, thyroid issues, or LPR. Post-nasal drip can be allergies, sinusitis, or LPR. Hoarseness can be vocal strain, smoking, neurological issues, or LPR. Without a clear diagnostic shortcut, most clinicians run down the more familiar paths first.

4. The Reflux Symptom Index isn't routinely used.

Belafsky, Postma, and Koufman published the Reflux Symptom Index (RSI) in 2002 as a 9-item validated questionnaire specifically designed to screen for LPR. Score above 13 suggests LPR. It's simple, free, and takes two minutes.

Most primary care doctors don't know about it. Most patients have never been asked the nine questions. An entire diagnostic tool exists and almost nobody uses it.

The Pepsin Problem

Here's where LPR gets mechanistically interesting, and where the standard reflux treatment playbook starts to fall apart.

When stomach contents reflux upward, they bring two damaging components: acid AND pepsin. Pepsin is the protein-digesting enzyme your stomach produces to break down food. In the stomach, it works alongside acid. But pepsin's behavior changes dramatically once it leaves the stomach.

Johnston, Dettmar, and colleagues published a landmark paper in Laryngoscope in 2007 showing exactly how pepsin behaves in the throat:

• Pepsin has maximum activity at pH 2.0 (highly acidic, stomach environment)
• Pepsin is inactive at pH 6.5 or higher (the normal throat pH is around 6.8)
• BUT pepsin remains stable up to pH 8.0
• AND pepsin can be reactivated when re-exposed to acid

In plain language: pepsin that reaches your throat goes dormant but doesn't go away. It binds to throat tissue. It gets absorbed into cells via receptor-mediated endocytosis (Johnston 2007, Annals of Otology). Then any subsequent drop in pH reactivates it.

The pH drops can come from:

• A subsequent reflux event bringing more acid
• Acidic foods or beverages (anything with pH below 5)
• Even normal swallowing of acidic saliva during high-stress situations

This is why people with LPR can have ongoing throat damage and symptoms WITHOUT obvious daytime acid reflux events. The pepsin is already up there, waiting to be reactivated by something they eat, drink, or do.

The clinical implication is the part that matters most.

PPIs reduce stomach acid production. Less acid means less acidic reflux. But:

• Pepsin is still being produced in the stomach
• Pepsin still travels upward with reflux events (now less acidic, but still containing pepsin)
• Pepsin still binds to throat tissue
• Once bound, ANY subsequent pH drop reactivates it

You can suppress acid all you want. As long as pepsin is reaching the throat and binding there, damage continues.

This is why several randomized placebo-controlled trials of PPIs for LPR have shown disappointing results. McGlashan and colleagues note in their 2009 paper that "several randomised placebo-controlled trials of proton pump inhibitors in the treatment of LPR have been reported with the majority showing no significant benefit in patient symptom scores over placebo."

PPIs treat acid. LPR is largely about pepsin. Different problem, different mechanism, often the wrong tool.

Why Alginate Is Mechanically Different

This is where alginate's mechanism becomes genuinely interesting for LPR specifically.

Alginate doesn't change stomach acid production. Alginate forms a physical gel barrier (called a "raft") that floats on top of stomach contents and physically blocks reflux at the gastroesophageal junction. The raft persists for two to four hours after each dose.

For GERD, this matters because it blocks acid from refluxing. For LPR, this matters because it blocks both acid AND pepsin from refluxing. Whatever can't make it past the raft can't reach the throat. And pepsin that can't reach the throat can't bind to throat tissue and can't be reactivated later.

The full mechanism is covered in Article 1: What Is an Alginate Raft and How Does It Work? What's relevant for LPR specifically is that alginate addresses the actual mechanical event (reflux reaching the throat) rather than trying to make the reflux less damaging once it gets there.

What the Research Says About Alginate for LPR

Several clinical trials have specifically tested alginate for LPR, and the results have been more consistent than the PPI literature.

McGlashan et al. 2009 (European Archives of Otorhinolaryngology) compared liquid alginate suspension (Gaviscon Advance) to placebo in LPR patients. Alginate patients showed statistically significant improvements in both the Reflux Symptom Index (RSI) and the Reflux Finding Score (RFS) at both 2 months and 6 months. This is the landmark alginate-for-LPR trial.

Tseng et al. 2018 (Laryngoscope) ran a double-blind placebo-controlled study of alginate suspension for LPR. Alginate produced significant symptom improvement, though a large placebo effect made it difficult to demonstrate superiority over placebo statistically. The study confirmed alginate is well-tolerated and produces real symptom reduction, while highlighting the importance of lifestyle modification alongside any intervention.

Wilkie et al. 2018 (European Archives of Otorhinolaryngology) compared alginate alone (four times daily) to alginate plus a twice-daily PPI in LPR patients. At three-month follow-up, RSI scores were essentially identical between the two groups, suggesting that adding a PPI to alginate offered no additional benefit and alginate alone was doing the work.

A 2025 systematic review in PubMed titled "Alginates and laryngopharyngeal reflux: where we stand" concluded that "alginates demonstrate a beneficial role both as monotherapy and as adjunct therapy with proton pump inhibitors" for LPR.

This is a meaningfully different evidence profile than the PPI-for-LPR literature, where trials have repeatedly failed to show significant benefit over placebo.

None of this means alginate is a cure for LPR. LPR is complex, often multifactorial, and frequently requires a combination of approaches. But the research suggests alginate is one of the few interventions with consistent positive data for LPR specifically.

The Lifestyle Factors That Actually Matter

Alginate addresses the mechanical reflux event, but it can't change the upstream factors that cause reflux in the first place. For LPR specifically, several lifestyle factors are well-supported in the literature:

Low-acid diet. Since pepsin reactivates with any pH drop, foods and drinks below pH 5 can perpetuate symptoms even without active reflux events. This is the principle behind Koufman's "low-acid diet" protocol for LPR. The biggest offenders: coffee, citrus, tomatoes, vinegar, carbonated drinks, alcohol, and most fruit juices. Many LPR patients see meaningful improvement just from removing these triggers.

Head-of-bed elevation. Six to eight inches of elevation under the head of the bed (not just extra pillows, which only bend the neck) uses gravity to keep stomach contents below the upper esophageal sphincter during sleep. This matters more for LPR than GERD because LPR damage often happens at night when reflux can travel further upward without the daytime swallowing reflexes clearing it.

Three-hour fasting window before bed. Don't eat within three hours of lying down. An empty stomach has less to reflux. This single change often produces noticeable improvement within two weeks for chronic LPR sufferers.

Left-side sleeping. The stomach is anatomically positioned such that left-side sleeping keeps the gastroesophageal junction above the level of stomach contents, while right-side sleeping puts the junction below. Studies have shown right-side sleeping significantly increases reflux events. Left-side sleeping is a free, drug-free intervention with real evidence behind it.

Avoid late-evening triggers. Tight-waisted clothing, large meals, vigorous exercise within two hours of bed, and lying down immediately after meals all increase reflux pressure. These are particularly impactful for LPR patients.

Stay hydrated with non-acidic water. Mild alkaline water (pH 8.0+) has been suggested as potentially beneficial for LPR specifically because it may help deactivate pepsin in the throat (Koufman and Johnston 2012, Annals of Otology). Plain water above pH 7 is sufficient for most people.

These aren't fringe recommendations. Most are in mainstream LPR clinical guidance from major ENT organizations. They're just rarely communicated clearly to patients, who often hear "avoid trigger foods" without specifics on which foods or why.

Where Reflux Shield Fits

Reflux Shield is built around the alginate raft mechanism. Sodium alginate as the active ingredient, calcium carbonate to cross-link the gel, sodium bicarbonate to generate the CO₂ that makes it float. Cheesecake flavor. Vegan, gluten-free, non-GMO, made in the USA.

One teaspoon after meals and before bed.

For LPR specifically, this matters because the mechanism addresses what the research suggests actually causes ongoing damage: pepsin reaching the throat. The raft blocks both acid and pepsin from refluxing past the gastroesophageal junction. Whatever doesn't reflux can't bind to throat tissue.

For LPR patients currently on a PPI: alginate is well-studied as add-on therapy and may address what your PPI doesn't (Reimer 2016 showed alginate added to PPI improved symptom control in inadequate responders). Don't stop your PPI without talking to your doctor. Alginate is additive to existing acid suppression, not a replacement.

For LPR patients who haven't tried PPIs or have stopped responding to them: alginate is supported by stronger trial data for LPR than PPIs are. This is worth discussing with your ENT or gastroenterologist.

None of this is medical advice and none of it replaces a conversation with your doctor about your specific situation. But alginate is one of the few tools with consistent positive data for LPR, and most patients have never been told it exists.

Frequently Asked Questions

How is LPR different from GERD?

GERD lives in the chest: heartburn, regurgitation, esophageal symptoms. LPR lives above the collarbone: throat clearing, cough, hoarseness, globus sensation, post-nasal drip. Most LPR patients don't have classic heartburn, which is why LPR is so often missed. Both involve reflux of stomach contents, but LPR involves contents reaching the throat and pepsin damaging tissues that aren't designed to handle it.

How do I know if I have LPR?

The Reflux Symptom Index (RSI) is a 9-item validated questionnaire designed exactly for this. Score above 13 suggests LPR is likely. You can find the RSI online and self-administer it in two minutes. If you score above 13 AND you have persistent throat symptoms that aren't responding to other treatments, bring the score to an ENT or gastroenterologist and specifically ask about LPR.

My doctor said my reflux tests were normal but I have all these symptoms. Could it still be LPR?

Yes, and this is a very common scenario. Standard endoscopy and pH monitoring often miss LPR because the reflux events are brief, upright, and travel quickly past the esophagus to the throat. Specific LPR-targeted testing (oropharyngeal pH monitoring, salivary pepsin testing) exists but isn't widely available. Many ENTs diagnose LPR clinically based on the symptom pattern and Reflux Finding Score on laryngoscopy.

Why didn't my PPI work?

PPIs reduce stomach acid. LPR damage is largely caused by pepsin, which travels with reflux events regardless of how acidic they are. Even on a PPI, pepsin still reaches the throat with each reflux event, binds to tissue, and reactivates with any subsequent pH drop. Several randomized trials have shown PPIs offer limited benefit over placebo for LPR specifically. This doesn't mean PPIs are wrong for everyone with LPR. It does mean they're not addressing the actual mechanism for many patients.

Should I take alginate even if I'm on a PPI?

This is a conversation for your prescribing doctor, but the research supports combination therapy. Wilkie 2018 and Reimer 2016 both showed alginate as add-on therapy improved symptom control in patients on PPIs. The mechanisms complement each other: PPI addresses acid production, alginate addresses the mechanical reflux event.

Will the low-acid diet help my LPR?

It's one of the most consistently recommended interventions in LPR literature. Koufman's research specifically supports it. The underlying logic: pepsin already bound to throat tissue reactivates with pH drops. Removing dietary acid removes one of the most common triggers. Many LPR patients see meaningful improvement within 2-4 weeks of strict adherence. The hardest part is identifying that coffee, citrus, tomatoes, vinegar, and carbonated drinks are essentially off the menu.

How long does it take to know if alginate is working?

Most studies measure outcomes at 2 months and 6 months. Many patients notice symptom improvement within 2-4 weeks, but throat tissue healing takes longer than symptom relief. The McGlashan trial showed continued improvement between month 2 and month 6, suggesting full benefit takes time.

Is alginate safe long-term?

Sodium alginate isn't absorbed systemically. It's been used clinically in the UK and Europe for decades with an extensive safety record. The main practical consideration is spacing it 30 minutes apart from other oral medications, since the gel layer can theoretically affect absorption.

What about surgery?

For severe refractory LPR with confirmed mechanical issues (large hiatal hernia, severe sphincter incompetence), fundoplication and other anti-reflux surgeries are options that some patients pursue. These are major decisions made with surgeons who specialize in foregut surgery. Most LPR patients don't need surgery and respond to conservative management.

Sources

Koufman JA. The otolaryngologic manifestations of gastroesophageal reflux disease (GERD): a clinical investigation of 225 patients using ambulatory 24-hour pH monitoring and an experimental investigation of the role of acid and pepsin in the development of laryngeal injury. Laryngoscope. 1991;101(4 Pt 2 Suppl 53):1-78.

Belafsky PC, Postma GN, Koufman JA. Validity and reliability of the reflux symptom index (RSI). J Voice. 2002;16(2):274-277.

Johnston N, Dettmar PW, Bishwokarma B, Lively MO, Koufman JA. Activity/stability of human pepsin: implications for reflux attributed laryngeal disease. Laryngoscope. 2007;117(6):1036-1039.

Johnston N, Wells CW, Blumin JH, Toohill RJ, Merati AL. Receptor-mediated uptake of pepsin by laryngeal epithelial cells. Ann Otol Rhinol Laryngol. 2007;116(12):934-938.

McGlashan JA, Johnstone LM, Sykes J, Strugala V, Dettmar PW. The value of a liquid alginate suspension (Gaviscon Advance) in the management of laryngopharyngeal reflux. Eur Arch Otorhinolaryngol. 2009;266(2):243-251.

Koufman JA, Johnston N. Potential benefits of pH 8.8 alkaline drinking water as an adjunct in the treatment of reflux disease. Ann Otol Rhinol Laryngol. 2012;121(7):431-434.

Tseng WH, Tseng PH, Wu JF, et al. Double-blind, placebo-controlled study with alginate suspension for laryngopharyngeal reflux disease. Laryngoscope. 2018;128(10):2252-2260.

Wilkie MD, Fraser HM, Raja H. Gaviscon Advance alone versus co-prescription of Gaviscon Advance and proton pump inhibitors in the treatment of laryngopharyngeal reflux. Eur Arch Otorhinolaryngol. 2018;275(10):2515-2521.

Reimer C, Lødrup AB, Smith G, Wilkinson J, Bytzer P. Randomised clinical trial: alginate (Gaviscon Advance) vs. placebo as add-on therapy in reflux patients with inadequate response to a once daily proton pump inhibitor. Aliment Pharmacol Ther. 2016;43(8):899-909.

Tsilivigkos C, Papantoniou K, Vitkos EN, Ferekidis E, Warnecke A. Alginates and laryngopharyngeal reflux: where we stand. A systematic review. Eur Arch Otorhinolaryngol. 2025;282(11):5751-5764.