When you stand up from a chair, your body should automatically adjust your blood pressure to keep you from feeling dizzy or fainting. But for people with autonomic neuropathy, that automatic response breaks down. Their blood pressure plummets, their heart races, and sometimes they pass out. At the same time, food sits in their stomach for hours, they vomit at night, or they alternate between constipation and explosive diarrhea. These aren’t random quirks-they’re signs of a hidden neurological disorder damaging the nerves that control your insides.

What Exactly Is Autonomic Neuropathy?

Autonomic neuropathy isn’t one disease. It’s a breakdown in the autonomic nervous system-the part of your nerves that runs your body without you thinking about it. It controls your heart rate, blood pressure, digestion, sweating, and even bladder function. When these nerves get damaged, your body can’t respond properly to changes in position, food intake, or stress.

Most cases-85% to 90%-are tied to long-term diabetes. High blood sugar slowly fries the tiny blood vessels that feed these nerves. But it’s not just diabetes. Autoimmune disorders, certain chemotherapy drugs like vincristine, Parkinson’s disease, and even some viral infections can trigger it too. The problem? Most people don’t realize they have it until symptoms get bad. Studies show only about 30% of primary care doctors recognize the signs early. That means many patients suffer for years before getting a diagnosis.

Why Your Blood Pressure Crashes When You Stand Up

One of the most dangerous and common symptoms is orthostatic hypotension. That’s just a fancy term for when your blood pressure drops too much when you stand. The definition? A drop of 20 mmHg in systolic pressure or 10 mmHg in diastolic within three minutes of standing. In severe cases, people drop from 120/80 to 85/55 in seconds.

This happens because the sympathetic nerves that normally squeeze your blood vessels to push blood upward aren’t firing. Without that squeeze, blood pools in your legs and belly. Your brain doesn’t get enough oxygen. That’s when you feel lightheaded, blurry vision, or worse-you faint.

Studies show 30% of people with diabetic autonomic neuropathy have this problem. But it’s worse than that. In one study of 450 patients, 68% had systolic blood pressure below 90 mmHg when standing. And 42% had symptoms like dizziness or near-fainting at least once a week. Even walking across a room can trigger it. The 6-minute walk test reveals another clue: these patients only reach 55-65% of their expected heart rate, while healthy people hit 85-90%.

There’s also POTS-Postural Orthostatic Tachycardia Syndrome. It’s not the same as orthostatic hypotension. In POTS, your blood pressure doesn’t drop much, but your heart rate spikes by 30 beats per minute or more when you stand. It’s common in young women and can feel like your heart is trying to escape your chest. Around 1 to 3 million Americans have POTS, and many are misdiagnosed with anxiety.

What’s Going On With Your Stomach and Gut?

While blood pressure crashes grab attention, the gut symptoms are just as disabling-and often more embarrassing.

Gastroparesis is the big one. It means your stomach doesn’t empty on time. Normal stomachs empty in under two hours. In gastroparesis, more than 10% of food is still sitting there after four hours. That’s measured with a gastric emptying scan, the gold standard. About 30% of people with autonomic neuropathy have it. And it’s not just bloating. People vomit-often at night. One study found 78% of gastroparesis patients with this condition vomit during sleep. Nearly half vomit daily.

Constipation hits 60% of patients. Bowel movements drop from a normal 4-5 per week to just 1.2. Then, suddenly, they get diarrhea-often at night. About 25% have this alternating pattern. Why? The nerves controlling the colon are damaged. Sometimes the colon is too slow. Other times, bacteria overgrow in the small intestine (SIBO). In fact, 52% of autonomic neuropathy patients with GI symptoms test positive for SIBO, compared to just 15% in healthy people. That’s why bloating, gas, and diarrhea stick around even when you eat clean.

Swallowing gets harder too. Up to 60% have abnormal esophageal contractions. That means food feels stuck, or you choke on liquids. It’s not just discomfort-it’s a choking risk.

How Doctors Diagnose It

There’s no single blood test. Diagnosis relies on symptoms and specific tests.

For blood pressure issues, the 10-minute active stand test is the first step. You lie down for five minutes, then stand up. Your blood pressure and heart rate are checked every minute. A drop of 20/10 mmHg confirms orthostatic hypotension. Heart rate variability during deep breathing is another clue-if your heart doesn’t speed up and slow down properly with breathing, your nerves are damaged.

For the gut, gastric emptying scintigraphy is still the best test. You eat a meal with a tiny bit of radioactive tracer, then a camera tracks how fast it leaves your stomach. Newer wireless capsules that measure pressure and pH as they move through your gut are 92% accurate and don’t require radiation.

There’s also the COMPASS-31 questionnaire-a 31-question survey that scores autonomic symptoms from 0 to 100. A score above 30 means significant dysfunction. It’s not perfect, but it correlates with real test results 85% of the time.

What Treatments Actually Work

There’s no cure. But you can manage symptoms-and many people do much better than they expect.

For low blood pressure:

• Fludrocortisone helps your body hold onto salt and water. It works for 60% of people, but 35% end up with high blood pressure when lying down.
• Midodrine tightens blood vessels. It’s effective in 70% of cases, but you have to take it only when upright-no doses after 6 PM or you’ll sleep with dangerously high BP.
• Compression stockings (30-40 mmHg) help push blood back up. They reduce symptoms by 35%.
• Abdominal compression garments help both blood pressure and stomach emptying. One Mayo Clinic trial showed a 40% drop in dizziness.
• Ivabradine slows down a racing heart in POTS. It cuts heart rate by 15-25 bpm in 65% of users.

For gut problems:

• Metoclopramide used to be the go-to drug. It improves emptying in half of patients. But it can cause permanent twitching (tardive dyskinesia) after 12 weeks. Most doctors avoid it now.
• Erythromycin works fast but stops working after a few weeks. Most people develop tolerance.
• Pyridostigmine is now recommended as a first-line option. It improves symptoms in 55% of people with minimal side effects.
• Diet changes make a huge difference. Eating six small meals a day, cutting fat to under 25g, and fiber to under 10g reduces vomiting and bloating by 50% in 60% of patients.
• Low-FODMAP or low-residue diets help with SIBO and diarrhea. Many patients report fewer nighttime bathroom trips and less bloating.

Life With Autonomic Neuropathy

This isn’t just a medical condition. It’s a lifestyle shifter.

People avoid hot showers, standing in long lines, or eating out. One Reddit user said, “I stopped going to restaurants because I never knew if I’d vomit in the middle of dinner.” Another said, “I wear compression leggings every day. It’s not glamorous, but I can stand long enough to get groceries.”

The average time to diagnosis? Nearly five years. Many see three or more doctors before someone connects the dots between dizziness, vomiting, and fatigue.

But there’s hope. New research is moving fast. The NIH is testing fecal transplants for gut symptoms-with early results showing 40% improvement in quality of life. Blood tests measuring neurofilament light chain are becoming possible, which could detect nerve damage before symptoms start.

The American Diabetes Association now recommends annual screening for autonomic neuropathy in anyone with diabetes for more than seven years. That could catch 500,000 new cases a year.

What You Can Do Today

If you have diabetes and you’re feeling dizzy when you stand, or you’re vomiting at night, or you’re constipated but then suddenly have diarrhea-don’t ignore it. These aren’t normal aging issues. They’re warning signs.

Start by tracking your symptoms. Write down:

• When you feel dizzy (after standing? after eating?)
• How often you vomit or have diarrhea
• How many bowel movements you have per week
• Whether you feel better sitting or lying down

Talk to your doctor about the 10-minute stand test and COMPASS-31. Ask if you should get a gastric emptying scan. Don’t wait for symptoms to get worse.

And if you’re already diagnosed: you’re not alone. Thousands are managing this with compression gear, diet tweaks, and smart medication timing. It’s not easy. But it’s manageable. And the more you understand it, the more control you regain.