Why Do People Throw Up When They Are Too Happy, Too Angry, or Too Scared?

Have you ever wondered why some people vomit at weddings, get diarrhea before exams or job interviews, or faint during rock concerts? Or how to prevent those embarrassing situations from happening to you? And on the flip side, why do others get constipated when the stock market crashes or while waiting for a performance review?

And why do responses to high-stress situations like these hijack your body and mind? Or why do they shut down digestion, increase fear and anxiety, and leave behind a cascade of mental and gastrointestinal disorders that can follow you for life?

Also, why are stress-related vomiting, diarrhea, and fainting not well understood by medical professionals, and why are perfectly healthy people commonly overdiagnosed, overtreated, or dismissed as hysterical cranks after these events?

The unfortunate journey from super-happy bride to out-of-the-blue nausea, vomiting, and diarrhea right before the wedding ceremony.

I'll answer these and many other questions to help you understand what's happening, why it happens, and what to do about it before, during, and after the accident so you can stay in control and protect yourself from unnecessary treatments, medical errors, and financial losses.

Shocking events lead to shocking outcomes

When you experience extreme emotions, positive or negative alike, your nervous system triggers a massive release of insulin, glucagon, cortisol, adrenaline (epinephrine), noradrenaline (norepinephrine), and vasopressin hormones.

• Insulin and glucagon are responsible for glucose regulation. Insulin prompts glucose uptake by cells, while glucagon stimulates the breakdown of glycogen, a form of glucose storage in the liver. Together, they maintain glucose balance (homeostasis), even during fasting or between meals. This mechanism enables people to maintain steady energy levels. In high-stress situations, the level of blood glucose in healthy individuals can exceed 180 mg/dL (~10 mmol/L), nearly double the normal upper limit. This condition is called stress hyperglycemia.
  

• Cortisol, adrenaline, and noradrenaline are commonly referred to as stress hormones in a negative sense, but this isn't entirely correct because they are present in circulation round-the-clock and play essential roles in regulating energy metabolism, cardiovascular function, mood, and the sleep-wake cycle. Their "stress hormone" label stems from their elevated levels during high-stress situations discussed on this page.

• Vasopressin regulates water retention by acting on the kidneys to increase water reabsorption. It also indirectly influences blood pressure by increasing blood volume and acting as a vasoconstrictor at higher concentrations in high-stress situations.

When all these hormones go into the override in response to stress, the combination of elevated heart rate, increased cardiac output, vasoconstriction, and hyperglycemia rapidly raises blood pressure to divert blood, glucose, and oxygen where they are needed most. A classic fight-or-flight response.

If an actual fight or flight follows, your muscles use the surge of energy to deliver peak performance and burn through it fast. But when there’s no outlet to absorb the pent-up energy, you’re still left with a dangerously elevated blood pressure.

To prevent the harm from sky-high blood pressure, the body trips its built-in circuit breakers. The fastest one is vomiting. The next one is diarrhea. Then the fainting. Or all three.

A Piece of Cake for Some, a Total Meltdown for Others

Can you prevent these outcomes from happening to you? Yes, you can, to a degree...

Have you ever seen a marine, a firefighter, or a police officer vomit or faint when facing an ambush, a raging fire, or an armed suspect?

Maybe a rookie, but not someone seasoned. That’s called adaptation, and it comes with training and experience.

By the end of this page, I’ll teach you fourteen shortcuts to prevent or, at the very least, reduce the severity of these extreme reactions. But first, you need to understand why they are happening beyond the simplified explanation above.

Knowing the physiology of extreme stress is important because once you realize that what’s happening to you, technically speaking, is normal and that there is nothing wrong with you, you’ll be prepared to deal with it and save yourself a ton of time and money from embarrassment, ruined events, injuries, and unnecessary medical care.

So, let’s delve into it.

What’s at Stake?

We have already established that high-stress events may cause extreme blood pressure spikes in the healthiest of people, regardless of their age or gender. If left uncontrolled, they can cause one or more of the following damages:

• A hemorrhagic stroke from a blood vessel rupture inside the brain that will cause permanent damage or death.

• Fainting, or a sudden loss of consciousness when the body overcorrects a sudden blood pressure surge with a sudden drop. The medical term for this condition is syncope, and it may have other causes.

• Aortic rupture causes the tear of the aorta, the body’s largest artery. This condition is fatal without immediate surgery.

• Fatal arrhythmias, or a dangerously fast or chaotic heartbeat triggered by extreme blood pressure. It can cause cardiac arrest that is rarely survivable, even if it happens in a hospital cardiological wing.

• Kidney injury and loss of function can occur when extreme blood pressure blows up the glomeruli—the tiny filtration units in the kidneys.

• Severe nosebleeds caused by the rupture of the fragile vessels in the nasal passages. It is not a life-threatening condition for healthy people, but it is hard to control and outright scary for people unaccustomed to the sight of blood, and a real medical emergency for anyone taking blood thinners affected by hemophilia, borderline scurvy and other blood disorders. Or imagine having a severe nosebleed while wearing a wedding gown.

• Eyesight at risk, too. Retinal hemorrhage or retinal detachment may occur from excessive blood pressure and cause permanent vision loss.

So, as you can see, the stakes are high, to say the least, and that’s why the body engages the built-in circuit breakers to preempt and prevent these and other potential damages.

The Mess That Follows Tripped Circuit Breakers

Nausea, vomiting, or retching

In response to the blood pressure spike, the body may release up to 400 ml of blood plasma into the stomach. This physiological response is called emesis, and it is one of the fastest ways to reduce dangerously high blood pressure quickly. The rapid distension of the stomach by the fluid activates the vomiting reflex, which is experienced as nausea and the urge to vomit.

Diarrhea or profuse bowel movement

A stomach already distended with food and fluids is less likely to trigger vomiting. In that case, the secretory diarrhea becomes the next blood pressure-release mechanism.

The diarrhea or a massive bowel movement results from stool being diluted by plasma-based fluids rapidly secreted into the colon. Once these fluids reach the rectum, they increase intrarectal pressure and trigger an immediate and near-uncontrollable urge to defecate.

If you anticipate an event that might provoke this reaction, consider wearing a high-capacity diaper, although even that may not be enough, as the volume of fluid and stool can easily exceed its capacity.

Fainting (blackout, syncope)

A fainting in a high-stress situation (neurally mediated reflex syncope) is the circuit breaker in reverse. The nervous system shifts into full parasympathetic mode: the heart rate slows, blood vessels dilate, and blood pressure drops precipitously. As a result, blood flow to the brain falls, the person passes out, and collapses to the floor unless already sitting down in a chair/couch with side supports.

The early warning signs of fainting appear seconds before the loss of consciousness and typically include paleness, dizziness, lightheadedness, sweating or cold, clammy skin, a vision blurring or fading, feeling weak or unsteady, and a fast or irregular heartbeat.  

If you are witnessing someone about to faint, act quickly to prevent a fall by helping them lie down immediately, preferably on their back, to restore blood flow to the brain. There are usually only 5–10 seconds from the onset of fainting, so prompt action is crucial to prevent injury.

The best way to prevent a fall when someone is about to faint is to support them from behind by placing your arms under their armpits, bending your elbows with palms pointing up, and allowing their weight to rest against your body for stability. 

Avoid reaching around their chest, as this can shift their center of gravity away from you and make it harder to support them. Keep your feet shoulder-width apart for extra balance. 

Regardless of the person’s weight, gradually lower both yourself and the person to the floor by bending your knees and moving down together, ensuring a safe and controlled descent to prevent injury.

If lying down isn’t possible, have them sit and put their head between their knees, and support them physically as they move to the ground or a chair to prevent a sudden collapse. Keep them lying or sitting for at least 10–15 minutes or until they feel fully recovered.  

If you ever need to assist someone who has already fainted, keep them lying down until they come around. Don’t lift their head or try getting them up because that only delays recovery by keeping blood from reaching the brain. If they start to vomit, turn their head to the side so they don’t choke on their vomit.

If a person doesn’t regain consciousness within one minute, call 911.

Most fainting episodes resolve in 20 to 30 seconds. If they stay unresponsive longer than a minute, it could be something more serious. Even if they regain consciousness quickly, call for help if they:

— Fainted during exertion, not after stress;

— Are pregnant, elderly, or have a known heart condition;

— Hit their head, fall hard, fractured the bone, can't move, bleeding, or in pain;

— Have no memory of what happened;

— Complained earlier of chest pain, racing heartbeat, or dizziness.

It's always better to overreact than to miss something more serious.

Impact of a single fainting episode on your health and valet

There are over 1.2 million hospital admissions annually for syncope in the United States, representing about 3% of all emergency department visits and 6% of hospital admissions.

Depending on your age and medical history, here is what to expect when admitted to the ER after the 'syncope' event. With minor variations, this is the standard diagnostic protocol followed by emergency physicians in the United States:

1. Detailed history debrief: events before/during/after syncope, medications, family history of sudden death.

2. Physical exam: includes blood pressure measurements and cardiac and neurologic assessments.

3. 12-Lead Electrocardiogram (ECG): Mandatory for all patients to detect arrhythmias, ischemia, or structural abnormalities.

4. Cardiac Testing: Echocardiography for suspected structural heart disease.

5. Tilt-Table Testing: For recurrent syncope with suspected neurocardiogenic cause.

6. Lab Tests: Limited to specific cases (e.g., hematocrit for anemia, troponin for ischemia).

7. Radiography: CT/MRI scan of the head or full-body "just in case." One unnecessary examination may sound innocent, but according to the most recent research,  CT Scans in a Single Year Could Result in 100,000 Future Cancers in the U.S., so it's best to avoid them.

8. Observation: For intermediate-risk patients, 6+ hours of monitoring and targeted testing.

The average cost in the United States for syncope admissions typically ranges from $32,798 to $35,242, depending on the hospital location and charter. These figures reflect the hospital charges for the admission itself and generally do not include the cost of ambulance transport, post-discharge follow-up care, or outpatient testing when indicated.

For otherwise healthy people, the primary medical risks from syncope-related hospital admission are already mentioned X-ray exposure from computer tomography, antibiotic-resistant Infections (>570,000/annually), and any number of inadvertent medical errors that take place in the hospitals (approximately 400,000/annually and over 200,000 deaths).

The impact of a syncope episode on your mental health is a far greater risk because it can cause significant anxiety about recurrence, fear of underlying serious conditions, and potential loss of independence, especially if driving restrictions are imposed. 

Many patients report psychological distress following syncope events, including depression and decreased quality of life, particularly when the cause remains uncertain after evaluation. And when the cause is a high-stress event — it is ALWAYS uncertain. For a perfectly healthy young adult, getting hit with something like this on the head isn't a trivial matter.

Now, let’s talk about how to avoid puking or soiling yourself when the blood pressure hits.

Even if you can’t stop a blow-up, make it less painful

Let me start by saying that you can’t really stop vomiting or diarrhea if your blood pressure spikes to a dangerous level. They’re the outcomes of a bad situation, not the cause.

But you can, to some extent, foresee and reduce their severity, and here’s how:

• Keep the stomach empty. The fuller your stomach, the more violent the reaction if plasma is dumped into it. Vomiting lasts longer and is harder to stop. Avoid any meals containing proteins for 6 to 8 hours and light carbohydrates and fluids for 1 to 2 hours before a high-stress event.

• Cleanse the colon. Using a fast-acting saline laxative such as milk of magnesia or magnesium citrate the night before a high-stress event reduces the volume of stool in the large intestine. You may still get diarrhea, but it’ll be lighter and shorter.

  If you recall, I mentioned earlier that vomiting is less likely when the stomach is full. But given the choice between vomiting and diarrhea, vomiting is easier to control and far less offensive. Diarrhea tends to be messier and nearly impossible to contain.

• Avoid stimulants. Caffeine and energy drinks raise your baseline blood pressure. That means your body is already halfway to overreacting before the stress even starts. Skip large amounts of them for at least 6 to 12 hours if you know something’s coming. You may still need some to prevent withdrawal side effects.

• Zero alcohol. Alcohol is a false friend in extreme situations because it lowers blood sugar and spikes stress hormones on its own. That’s, incidentally, why drunk people are prone to rage. Combine that with elevated blood pressure, and you’ve got a risk of fainting or worse. If you’ve got something stressful ahead, don’t drink the night before, or you’ll pay for it.

• Cut the salt. High salt intake means higher fluid retention. When blood pressure surges, there’s more volume to push around, so the reaction hits harder. Reduce salty foods 24 to 48 hours before the event. It doesn’t take long to make a difference.

• Avoid protein-containing meals. Protein slows stomach emptying and increases gastric acid. If you vomit, it’ll be more acidic, more painful, and last longer. Skip meat, fish, and eggs before high-stakes events. You’ll thank yourself later.

• Don’t wear tight clothing. Tight corsets, waistbands, and belts raise abdominal pressure and limit the body’s ability to shift fluids where they need to go. That makes everything more intense, especially vomiting and diarrhea. Wear something loose. You’re not going to a fashion show.

• Stick to fluids and low-density foods. Starting two days ahead, eat foods that pass quickly, such as soups and broths. This keeps your stomach and intestines mostly empty and reduces acid levels. If the system trips, there’s less to come out and fewer consequences if it does.

• Keep glucose tablets on hand. Stress depletes blood glucose quickly and increases the risk of fainting, especially after fasting or prolonged exertion. Sublingual glucose tablets help prevent fainting due to hypoglycemia, which differs from fainting caused by elevated blood pressure and is easier to prevent. Each tablet typically contains 3 to 4 grams of pure glucose. When dissolved under the tongue, glucose rapidly enters the bloodstream through the oral mucosa and stabilizes blood sugar levels. Swallowed glucose or sugar does not have the same effect because it must first pass through the stomach before being absorbed in the small intestine. Sugar (sucrose) is less effective in emergencies than pure glucose because it consists of both glucose and fructose. Glucose tablets are available in the diabetes section of most pharmacies.

• Do-it-yourself Cognitive Behavioral Therapy. Rehearse the event in your mind as vividly as possible. Walk yourself through the worst version of it over and over until your body starts ignoring it. Then, when the real thing happens, it will feel familiar and won’t feel like a threat.

• Slow breathing. When the blood pressure builds, your breath becomes short. Slowing down your breathing reduces blood pressure and heart rate. Inhale for four seconds, hold your breath for six, and exhale for eight. It isn’t meditation, but blood pressure control. This mechanism works because slow breathing, especially exhaling, builds up CO2, and the CO2 dilates the blood vessels.

• Turn on the Diving reflex. Splash ice-cold water on your face or apply ice cubes in a napkin or plastic bag over your eyes and cheeks. The cold sensation triggers the diving reflex, which quickly lowers heart rate and blood pressure. The technique is often used in professional sports to reduce stress, anxiety, and panic on demand. That’s, incidentally, where the expressions ”cool off” and “hot under the collar” came from.

• Fear mitigation by preparation. If it’s a speech, give it to a friend. If it’s a test, practice the questions with ChatGPT. Preparation removes uncertainty, and that’s what your nervous system reacts to most.

• Stress conditioning. Stress reactions are trainable. The more often you face the stressor, the less dramatic your body’s response becomes. Repeat exposure to stressful situations rewires the reaction. It’s why veterans stay calm under fire and rookies vomit or faint. You don’t need courage, but reps.

There are also more radical approaches to resisting stress that involve prescription or recreational drugs, but that’s not my territory. Beyond the obvious legal risks, there’s the usual mess: overdose, hangovers, sedation, memory lapses, poor judgment, and the high likelihood of acting like a jerk.

Don’t be the one!

How to Lessen the Brutality of Retching

Retching (dry heaving) is the forceful, rhythmic contraction of the diaphragm and abdominal muscles that mimics vomiting but without expelling anything. It happens when the brain triggers the vomiting reflex, but the stomach is empty or may follow the vomiting, even though there is nothing left to expel.

The retching is often more exhausting and painful than vomiting itself. But there are a few ways to make it less traumatic:

• CO₂ Rebreathing Technique. Hold your breath for as long as you can, or breathe into a paper or plastic bag tightly sealed around your nose and mouth. Like meditative breathing, this technique rapidly increases carbon dioxide levels in your body and produces muscle relaxation and a calming effect that helps prevent you from spiraling into a full panic mode.

• Don't fight it by tensing your abdominal muscles. Stay leaned forward, support your arm with any stable object in front of you, and keep your abdomen relaxed. Tensing it up only makes retching worse.

• Put a cold towel or ice pack on your face or neck. It helps settle the vagus nerve and cool the vomiting reflex, thanks to the diving reflex that I described earlier.

• Avoid anything that stimulates your throat. No teeth brushing, no swallowing hard, no throat clearing. Just rinse your mouth gently with warm, slightly salted water and leave it alone.

• If the smell of vomit is still triggering you, distract your brain with something strong but clean, such as the smell of lemon or orange peel.

• Avoid drinking cold water or soda because it can start the cycle all over again. Wait until everything calms down, then take small sips of warm, salty water.  Crushed ice or popsicles are often easier to tolerate than sipping water.

Retching is sometimes exacerbated by the bile reflux from the duodenum into the stomach and its strong 'burning' effect on the mucosal membranes of the esophagus and throat.

Baking soda (sodium bicarbonate) rinse can help neutralize bile in the mouth and the stomach because of its alkaline properties. It provides relief from irritation or discomfort by counteracting the acidity of bile. Fully dissolve one teaspoon of baking soda in one cup of warm water. Swish the solution for up to one minute, spit it out, and rinse with plain warm water.

If tolerated, you can slowly drink the same backing soda solution to reduce the impact of bile and gastric acid in the esophagus and the stomach, but no more than once every two hours. Please note that this suggestion only applies to dealing with stress-related retching. If you are affected by bile reflux related to various medical conditions, consult your doctor.

Recovering After an Episode

This essay wouldn’t be complete if I didn’t tell you how to quickly and fully recover from an episode of vomiting, retching, or diarrhea without causing yourself further damage:

• Dehydration.Both vomiting and diarrhea cause dehydration, sometimes severe. You’ll feel it as dry mouth, dizziness, and fatigue. Short of getting a saline IV drip at a medical clinic, the fastest way to rehydrate is by slowly sipping drinking water mixed with 2 teaspoons (about 10 grams) of table salt per liter. When consumed on an empty stomach, this solution quickly reaches the small intestine and is fully absorbed into the blood. Salt is essential for water retention and for restoring blood volume.

• Sodium chloride (salt) deficiency. Prioritize the salt solution first because water alone can worsen dehydration by diluting salt even further. Start with a 1% commercial oral rehydration electrolyte solution or make one yourself until you slowly consume the first 1 to 2 liters.

• No sugar and fiber. Even small amounts of sugar or fiber can ferment in the gut and worsen cramping, bloating, or continued diarrhea. Avoid fruit juice, soda, and raw vegetables. Stick to broths, saline water, or diluted electrolyte solutions for the first 12–24 hours.

• No solid food. After an event like this, you’re unlikely to feel hungry for 12 to 24 hours due to dehydration. During this time, your body may not produce enough gastric acid to sterilize food or digest proteins properly. Eating solid food too soon can lead to indigestion or even foodborne illness. Focus on fluids for at least 12 hours, and only eat lightly for the next day or two once you genuinely feel an appetite and hunger.

• Avoid dairy products for 2 to 3 days. After diarrhea, the small intestine often temporarily loses lactase, the enzyme that breaks down lactose. Even if you’re not lactose intolerant normally, milk or cheese can trigger bloating and diarrhea during recovery.

• Skip the BRAT diet. Bananas, rice, applesauce, and toast are often recommended, but they don’t offer much salt and are likely to cause fermentation and bloating.

• No NSAIDs. Do not take non-steroidal anti-inflammatory drugs such as aspirin, Ibuprofen, or naproxen because they irritate the stomach lining, can make your symptoms worse, and prolong recovery.

Following these steps for up to 48 hours will help complete your full recovery and prevent lingering fatigue, stomach upset, intestinal bloating, and additional bouts of diarrhea. Don’t expect normal bowel movements to resume right after a major flush because it can take a day or two for the colon to refill to baseline. That’s normal.

If diarrhea continues beyond that, it likely means inflammation in the large intestine hasn’t fully subsided. This is uncommon after a single episode of secretory diarrhea in otherwise healthy individuals and may indicate a pre-existing issue.

High-stress events are equally notorious for causing severe constipation. It’s less dramatic than diarrhea, but just as disruptive and damaging to your gut health. You’ll find more information on this topic here than in any other resource in the world. Start here: How to Normalize Stools and Restore Natural Bowel Movements.

Author's note

We’re wired to survive the chaos with circuit breakers so ancient and brutal that they’d sometimes make even a combat medic or ER physician wince. And yet, we call them “embarrassing” when they kick in. Maybe the real embarrassment is how disconnected we’ve become from those survival mechanisms.

Despite the gory outcomes, I find this subject utterly fascinating and will continue to write new posts about the connection between emotions and digestion to help you preserve your health when either one goes askew.

Please share this post with your family and friends to support my work!

Thank you!

Konstantin Monastyrsky