Dr Lacy reviews his presentation from the ACG conference on the challenges of distinguishing functional dyspepsia and gastroparesis and finding the best treatments for these conditions.

Brian Lacy, MD, is a professor of medicine at Mayo Clinic-Florida in Jacksonville, Florida.

• Prevalence and Diagnosis: Functional dyspepsia affects ~10% of the global population versus gastroparesis (~1/10,000). Both present with similar foregut symptoms (epigastric fullness, pain, nausea, vomiting). Accurate differentiation requires upper endoscopy to rule out obstruction and gastric emptying testing (scintigraphy or breath test) to identify delayed or rapid emptying.
• Testing and Therapeutic Implications: Gastric emptying results help confirm diagnosis but do not predict symptom response. Accelerating gastric emptying does not always improve nausea or early satiety and may worsen symptoms in some patients. Many with functional dyspepsia have normal or rapid emptying—thus prokinetics may be inappropriate and potentially harmful.
• Symptom-Focused Management: Treatment should target the most bothersome symptom for the patient. For functional dyspepsia, neuromodulators can address pain. For gastroparesis-related nausea, consider antiemetics—metoclopramide (FDA-approved) or off-label options tailored by timing (e.g., scopolamine patch, promethazine, diphenhydramine). Reassure patients that neither condition increases gastric cancer risk and often improves over time.

Welcome. I'm Brian Lacy, professor of medicine at the Mayo Clinic in Jacksonville. I'm here in Phoenix, Arizona, at the American College of Gastroenterology 2025 annual meeting. One of my lectures at the postgraduate course this year was on functional dyspepsia and gastroparesis. This is a common conundrum that clinicians face when patients present with foregut symptoms of epigastric fullness, epigastric pressure, discomfort with eating, nausea, and vomiting. These are both common disorders and frequently it's hard to tease out which diagnosis is the correct one. So let me give you some tidbits from the postgraduate course lecture I did today.

The first is to really think about the prevalence of the disorder. So functional dyspepsia defined by symptoms of epigastric fullness, pressure, discomfort, using Rome IV criteria is actually quite common. It's about 10% of the global population, but as all of our listeners know, no patient ever comes in and says, I have functional dyspepsia. They just describe these nonspecific symptoms.

In contrast, gastroparesis is much less common, and we talk about one person in 10,000 having that disorder, again characterized by those same symptoms—pressure, pain, meal-related symptoms, including nausea and vomiting. Both disorders require an upper endoscopy to exclude an anatomic or mechanical cause for the symptoms, and so that's easy for all of us in our fields to accomplish.

A key branch point is the use of a gastric emptying scan. So I'm a big advocate for using scintigraphic testing or a breath test to measure gastric emptying objectively because those symptoms I've mentioned are quite nonspecific and you can't use those symptoms to make an accurate diagnosis.

And this is important for a number of reasons. One is that some patients, where you think they may have gastroparesis, have functional dyspepsia with rapid stomach emptying, but if you give somebody with dyspeptic symptoms and rapid stomach emptying a prokinetic agent or something to accelerate gut transit, you can make their symptoms worse.

Number two, many patients with functional dyspepsia— in fact the majority—have normal stomach emptying, and therefore the value of a prokinetic agent is probably much lower.

Lastly, the idea about a gastric emptying scan is for many of those patients where you presume they have gastroparesis, they may not or they may have rapid emptying, and you need to objectively determine the extent of delay in gastric emptying.

The next teaching point is that although I just mentioned that gastric emptying scans are important, either the scintigraphic scan or the breath tests, they're not great predictors in terms of how patients will respond. And so what I mean by that is you may have somebody with a mild delay in gastric emptying who does respond well to a prokinetic, but you may have somebody with a significant delay in gastric emptying who does not respond to a prokinetic at all. And so the results are important to make an accurate diagnosis, but it may not predict therapy.

Another important teaching point is when we think about patients with gastroparesis, we have many drug trials from the past showing that we can normalize gastric emptying, but symptoms persist. And so a great teaching point is that although gastroparesis is defined as delayed gastric emptying and the absence of mechanical obstruction, simply accelerating gastric emptying may not improve those symptoms of nausea, vomiting, early satiety, and it may actually worsen some of those symptoms.

So what to do with these complicated patients and challenging nonspecific symptoms? One is think about the most bothersome symptom the patient —just flat out ask them, what bothers you most? How can I help you today? And remember that for both groups of patients, either gastroparesis or functional dyspepsia, pain is typically a predominant symptom and feel comfortable, especially with patients with functional dyspepsia, using a neuromodulator, which might include a tricyclic antidepressant or tetracyclic antidepressant such as mirtazapine or maybe an SNRI-- serotonin norepinephrine reuptake inhibitor—such as duloxetine.

Thinking about that patient with gastroparesis as they walk into the room and they're talking about their nausea and their vomiting, think about antiemetic therapies that might be best for them. We have many, many different options. Remember that only one is FDA approved for the treatment of gastroparesis, metoclopramide. Others are technically all off-label, although we're comfortable with using them. So think about what's most bothersome in terms of nausea.

If they have chronic daily nausea, PRN medications won't be helpful, and maybe you need to consider a scopolamine patch or a centron patch if somebody has early morning nausea, but they do better as the day goes on, maybe use a medication at night promethazine as example, or Benadryl at bedtime so they don't awaken nauseated. If it's more meal related nausea that every time they eat they have some nausea, think about maybe using a low dose phenergan or a low-dose prokinetic, antiemetic agents such as metoclopromide before the meal to help prevent those episodes of nausea, vomiting related to meals.

Lastly, reassure your patients, especially for functional dyspepsia. This never turns anything bad or worse and does not increase the risk of stomach cancer. And there are lots of ways to treat this, including some investigational new things coming down the pike, which is very exciting. And similarly for gastroparesis, especially the idiopathic group, again, reassure them this does not increase their risk for stomach cancer or stomach ulcers, and generally this will improve with time and with medications. With that, again, coming from Phoenix, Arizona at ACG 2025, thanks for joining us here today, and I hope we learned a lot.