Nausea Causes and Treatments

Nausea is a queasy or uneasy sensation in the stomach that makes you feel as if you are about to vomit. It is a non-specific symptom that can be triggered by many things, including gastroenteritis ("stomach flu"), food poisoning, motion sickness, dehydration, morning sickness, chemotherapy, and even strong, off-putting smells.

Nausea is often self-limiting and will resolve on its own without treatment. However, there are over-the-counter (OTC) and prescription drugs called antiemetics that specifically treat nausea as well as natural remedies and dietary strategies that also help.

This article describes the causes and treatment of nausea. It also offers simple tips for relieving and preventing this all-too-common, unpleasant symptom.

What Nausea Feels Like

Nausea is an uncomfortable sensation in the back of the throat, middle of the chest, or top of your stomach. It is often accompanied by the urge to vomit but doesn't always lead to vomiting. The sensation may be dull and lingering or come on suddenly and severely.

Although nausea is not painful, it can be debilitating if it is severe or persistent. Depending on the underlying cause, you may also experience:

• Dizziness
• Lightheadedness
• Burping
• Upset or gurgling stomach
• Middle chest pain
• Heartburn
• Difficulty swallowing
• Increased salivation
• A feeling of a lump at the back of your throat

What Causes Nausea?

Nausea is a complex sensation triggered by the stimulation of nerve receptors in different parts of the body. These signals are received by the dorsal brainstem, the part of the brain that processes sensory information from the gut and regulates reflexes like swallowing, gagging, and burping.

Activation of the dorsal brainstem can cause gastric dysrhythmia in which muscles of the stomach move erratically and reverse the propulsion of the stomach contents toward the mouth. This, in turn, triggers nausea and possibly vomiting.

The abnormal activation of the dorsal brainstem involves one of four systems:

• Central nervous system: Increased pressure, infection, or irritation of the brain or surrounding membranes (meninges) can stimulate the dorsal brainstem and provoke nausea. Extreme emotions like anxiety can do the same.
• Vestibular system: The dysfunction of the inner ear and/or the vestibulocochlear nerve—both of which regulate balance—can lead to extreme dizziness and symptoms of nausea.
• Chemoreceptor trigger zone (CTZ): This is part of the dorsal brainstem that receives input from blood-borne drugs and hormones. Exposure to certain drugs or abnormal levels of hormones (like serotonin or dopamine) can trigger nausea.
• Peripheral pathways: These are nerve receptors that send warning signals to the dorsal brainstem if there is a problem in the gastrointestinal tract (such as toxins or obstruction) or other organ systems (such as the heart or liver).

In terms of anatomy, the causes of nausea can be broadly categorized as those that occur inside the abdomen (intra-abdominal) and those that occur outside of the abdomen (extra-abdominal).

Intra-abdominal Causes of Nausea

Problems in the gastrointestinal (digestive) tract account for the majority of nausea or vomiting episodes. This includes an almost encyclopedia array of conditions, such as:

• Gastroenteritis ("stomach flu")
• Food poisoning (including bacteria like E. coli or viruses like norovirus)
  
• Gastroesophageal reflux disease (GERD)
• Irritable bowel syndrome (IBS)
• Gastritis (stomach inflammation)
• Dysmenorrhea (including menstrual cramps)
• Cholecystitis (gallbladder inflammation)
• Gastroparesis (paralysis of the stomach muscle)
• Peptic ulcer (also known as a stomach ulcer)
• Celiac disease (an autoimmune condition triggered by eating gluten)
• Crohn's disease (a type of inflammatory bowel disease)
• Appendicitis (inflammation of the appendix)
• Acute hepatitis (severe inflammation of the liver)
• Pancreatitis (inflammation of the pancreas)
• Liver failure (the end stage of liver disease)
• Bowel obstruction (also known as an intestinal blockage)
• Kidney stones (hardened mineral clumps that form in the kidney)
• Pancreatic cancer (the 10th most common cancer)
  

Extra-abdominal Causes of Nausea

These involve conditions that activate the dorsal brainstem either directly or indirectly via organs outside the abdomen. Some of the more common causes include:

• Severe dehydration (often related to physical overexertion)
• Motion sickness (also known as travel sickness)
  
• Vertigo (spinning sensations related to the inner ear)
• Pregnancy (including morning sickness)
• Myocardial infarction (also known as a heart attack)
• Meningitis (inflammation of the meninges)
• Encephalitis (inflammation of the brain)
• Migraine headaches
• Traumatic brain injury (such as a blow to the head)
• Stroke (caused by the lack of blood flow to the brain)
• Brain tumors (both benign and cancerous)
• Glaucoma (a group of eye diseases characterized by increased inner eye pressure)
• Chemotherapy (used to treat cancer)
• General anesthesia (used to induce unconsciousness during surgery)
• Ergotamine (used to treat migraine)
• Drug withdrawal (including prescription and recreational drugs, including alcohol)
• Severe depression or anxiety
• Altitude sickness (caused by reduced oxygen levels at high altitudes)
• Exposure to toxic fumes (like carbon monoxide)
• Adrenal insufficiency (in which the adrenal glands do not produce enough steroid hormones)
• Off-putting scents (such as heavy perfumes, rotting food, or strong food smells)
  

Diagnosing Causes of Nausea

The diagnosis of nausea is dependent on its cause. Reporting any other symptoms and providing a complete medical history to your healthcare provider is essential to achieving a valid diagnosis. 

In addition to a physical exam, your healthcare provider may order blood or other laboratory and imaging tests.

How to Get Rid of Nausea

Nausea will often subside once the underlying condition is resolved. In severe or chronic cases, nausea can be managed with prescription drugs, OTC medications, changes in diet, and natural remedies.

Antiemetics

Antiemetics are prescription and OTC drugs used specifically to relieve nausea. Different medications are prescribed based on the underlying cause.

These include OTC antihistamines and anticholinergic drugs that are useful in treating motion sickness, stomach flu, and morning sickness, such as:

• Dramamine (dimenhydrinate)
• Bonine (meclizine)
• Benadryl (diphenhydramine)
• Unisom (doxylamine)
• Scopace patch (scopalomine)
• Pepto-Bismol (bismuth sulfate)

Prescription antiemetics may be used to ease nausea caused by migraines, gastroenteritis, chemotherapy, and postoperative nausea, such as:

• Reglan (metoclopramide)
• Compro (prochlorperazine)
• Thorazine (chlorpromazine)
• Decadron (dexamethasone)
  
• Zofran (ondansetron)
• Granisetron
  

Changes in Diet

Until your stomach settles, it helps to modify your food intake to a bland or soft diet. Recommended foods on this diet are easier to digest, less acidic, and lower in fiber. It is designed to give your digestive organs a rest.

The bland diet avoids fried and other fatty foods, spices, nuts and seeds, acidic fruits, whole grains, raw fruits and vegetables, and beans and vegetables that cause gas. Alcohol and carbonated drinks (which also cause gas) are also excluded.

A bland diet is based on cooked food. It includes but is not limited to broth, bland vegetables (carrot, beets, spinach), eggs, and lean meat and fish.

Natural Remedies

Ginger is an ancient Chinese herb used for digestive disorders for centuries. Studies have shown that ginger relieves nausea during pregnancy.

Both spearmint and peppermint essential oils were shown to reduce chemotherapy-induced nausea in cancer patients.  Peppermint aromatherapy was also shown to be effective in relieving nausea in women after undergoing a C-section.

A 2015 review of 23 randomized controlled trials reported that patients on chemotherapy who received cannabis-based medicines experienced less nausea than those who received a placebo (sham drug).  

When to See a Healthcare Provider

Nausea is generally a self-limiting condition but can sometimes be a sign of a severe illness in need of medical treatment. Seek immediate care if nausea occurs after a severe head injury or is accompanied by the following signs or symptoms:

• Sudden, severe headache  
• Severe abdominal pain  
• Vomiting blood  
• Extreme weakness  
• High fever (over 101 F)  
• Blurred vision or eye pain  
• Confusion
• Stiff neck  

For nausea lasting for more than one week unrelated to the above conditions, you should consult a healthcare provider.

How Long Does Nausea Last?

In many situations, nausea is a temporary symptom. For example, nausea from food poisoning will resolve fairly quickly once the toxins are passed. Similarly, post-surgical nausea typically resolves once the anesthesia is cleared from the body.

If you suffer from motion sickness, it will be relieved once the motion is ended. As pregnancy progresses, nausea will also decrease.

Speak with your healthcare provider about the medications you are taking, as they may be responsible for nausea.

When nausea is associated with a serious disease, it may take some time for the symptoms to be resolved. Your healthcare provider may prescribe antiemetic medications to help you better cope and function until the underlying condition is fully resolved.

How to Prevent Nausea

Nausea can't always be prevented, but if you are prone to nausea or feel nausea symptoms coming on, there are things you can do that may help:

• Take it easy: If you feel symptoms coming on, stop what you are doing and rest either in a seated position or a propped lying position. Lying flat can sometimes make symptoms worse.
• Avoid triggers: This includes avoiding anything that can cause motion sickness (like a carnival ride) or expose you to strong smells (like a cheese shop). People with morning sickness are particularly sensitive to smells.
• Stay well hydrated: If you are a long-distance runner or are planning a long outdoor excursion, bring along plenty of water to stay well hydrated.
• Sip clear liquids: You can sometimes abort symptoms of nausea by sipping flat ginger ale, ginger or peppermint tea, apple juice, broth, or cranberry juice. Some people also find relief by sucking on a popsicle or eating a small cup of fruit-flavored gelatin.
• Prepare for travel: You can reduce the risk of motion sickness by taking Dramamine beforehand. You can also help counter the effect by looking out into the horizon (rather than closing your eyes or looking down at your lap, which can make symptoms worse).
• Avoid infection: Food poisoning can be avoided by washing your hands with soap and water, avoiding hand-to-mouth behaviors, and staying clear of suspected food or drinks (particularly in foreign countries).
• Eat smaller meals: If you are prone to chronic nausea, try eating five or six snack-sized meals per day rather than three big meals. This avoids overtaxing the stomach. You should also cut back on fast, processed, or fatty foods that are more likely to induce symptoms.

Summary

Nausea is a common condition in which you feel like vomiting. It can be caused by many things, including infections and diseases of the stomach, intestines, brain, heart, liver, or nervous system. Nausea can also be caused by pregnancy or periods, certain medications, or extreme anxiety or depression.

Nausea is often self-limiting but can be treated with antiemetic drugs, a bland diet, or natural remedies like ginger, peppermint, or cannabis.