Nausea: What Is It, What Causes It, and How Is It Treated?

Nausea is one of the most common health issues people encounter in daily life, and it significantly impacts quality of life.

Nausea can occur as a result of normal body physiology, but it can also be a sign of underlying serious conditions. Treating nausea depends on accurately identifying the cause of the problem. In this sense, being informed about nausea and knowing what measures to take in its treatment is essential for a healthy life.

The digestive system performs a movement called peristalsis when food is consumed. This movement, which helps transport food from the esophagus to the end of the digestive tract, is necessary for the absorption of nutrients.

In some cases, the contents of the stomach may move in the opposite direction, performing a reverse peristaltic movement, causing food to move from the stomach back to the esophagus, into the mouth, and eventually out of the body.

What is Nausea?

Nausea is the feeling of discomfort in the stomach, accompanied by the urge to expel gastric contents.

What Causes Nausea?

Nausea can arise from a variety of conditions or circumstances. In some sensitive individuals, problems with how signals are interpreted in the brain during movement can occur, leading to motion sickness or seasickness.

Nausea is commonly experienced by women during their menstrual cycle due to hormonal changes in their bodies. If nausea is accompanied by other symptoms such as pain or fever, underlying conditions like dysmenorrhea, endometriosis, or premenstrual syndrome could be the cause, requiring further investigation.

Some of the most common causes of nausea include gastrointestinal issues, infections caused by bacteria or viruses, and medications related to other health conditions:

Gastrointestinal Problems
Certain digestive system issues can lead to nausea. Reflux is one of the leading gastrointestinal disorders that can cause nausea. In this condition, stomach contents move back up into the esophagus (food pipe). The burning sensation caused by this acidic content may trigger nausea.

Stomach and small intestine ulcers are another cause of nausea related to the digestive system. Pain and burning in ulcerated areas, particularly after meals, can lead to nausea.

Diseases Caused by Viruses or Bacteria
Bacteria and viruses can affect the stomach, causing nausea. Consuming food contaminated with bacteria can lead to food poisoning, a condition that may result in nausea.

Medications
Many medications can cause nausea as a side effect. Chemotherapy drugs used in cancer patients, in particular, can lead to intense nausea.

No medication prescribed by a doctor as part of a treatment plan should be stopped without the doctor's knowledge. Patients should consult their doctor regarding the potential side effects of prescribed medications.

Other causes of nausea include:

• Early pregnancy
• Intense pain from conditions like kidney stones or pancreatitis
• Exposure to chemical toxins
• Fear and other emotional stressors
• Gallbladder diseases
• Food poisoning
• Certain smells
• Vertigo
• Ear infections

The underlying cause of nausea can vary depending on age. In adults, the most common causes of nausea are viral infections, food poisoning, febrile illnesses, and motion sickness. In children, overeating, coughing, and febrile illnesses can be causes of nausea.

In rare cases, infants may experience nausea and vomiting due to blockages in the digestive tract, so attention is necessary.

Nausea can also be a symptom of serious health conditions, including:

• Concussion
• Encephalitis (inflammation of brain tissue)
• Meningitis (inflammation of the brain membranes)
• Digestive tract blockages
• Appendicitis
• Migraine
• Brain tumor
• Heart attack
• Liver failure
• Dehydration (fluid loss), which is a significant cause of nausea, especially in children, who are at greater risk. Dehydration symptoms in children include dry lips and mouth, sunken eyes, or rapid breathing, requiring close attention.

When combining all the factors, the causes of nausea can be summarized as follows:

• Motion sickness or seasickness: Nausea can occur due to problems with the brain's perception of the environment during travel by car or sea vehicle.
• Early pregnancy (especially the first trimester): The hormone beta-HCG, known as the pregnancy hormone, stimulates nausea. About 50-90% of pregnancies experience nausea, and 25-55% experience vomiting.
• Nausea and vomiting due to medication use: Some medications trigger the brain's vomiting center, causing nausea and vomiting.
• Intense pain: Severe headaches, like migraines, or other body pains can activate the vomiting center in the brain, leading to nausea.
• Emotional stress: High psychological stress can negatively affect the brain, triggering nausea.
• Food poisoning: Consuming foods contaminated with toxins or microorganisms can irritate the stomach and intestines, leading to nausea and vomiting.
• Infections: Infections in various parts of the body can cause nausea due to toxins produced by microorganisms or inflammation.
• Overeating or consumption of certain foods: Overeating or eating foods that irritate the stomach or digestive system can cause nausea and vomiting.
• Bad odors: Inhaling unpleasant smells can stimulate the brain and cause nausea.
• Gastrointestinal diseases: Reflux disease, stomach ulcers, gallbladder diseases, Crohn’s disease, and other conditions that affect the digestive tract often result in nausea and vomiting.
• Kidney and urinary tract diseases: Kidney stones and urinary tract infections often cause nausea due to pain and inflammation in the affected areas.
• Chronic diseases: Diseases that affect the liver and kidneys' ability to remove toxins, or various rheumatological and hormonal disorders, can lead to nausea.
• Brain injury: Head trauma, infections affecting the brain (such as meningitis), and changes in brain fluid can lead to nausea and vomiting.
• Psychological disorders like bulimia: Repeated eating and vomiting behaviors associated with eating disorders like bulimia may lead to nausea.
• Alcohol use: High alcohol consumption can lead to increased alcohol breakdown products in the bloodstream, affecting the liver and brain and causing nausea and vomiting.
• Various types of cancer: Substances produced by cancer cells, inflammatory reactions, and anatomical disruptions caused by tumors can result in nausea and vomiting.
• Allergy: Severe allergic reactions can cause nausea.
• Vertigo: Health problems like inner ear disorders, neurological issues, or vision disturbances causing dizziness (vertigo) can lead to nausea.

How does nausea occur?

Nausea can be defined as a feeling of discomfort in the stomach and intestines, accompanied by the urge to vomit. It is a precursor to the expulsion of stomach contents (vomiting). Since nausea can arise from various causes, its mechanisms also vary accordingly. The mechanisms involved in nausea can be summarized as follows:

1. Stimulation of the gastrointestinal system: Certain conditions that cause discomfort in the stomach and intestines (poisonings, infections, irritants, etc.) and some anatomical issues that block the gastrointestinal passage (intestinal obstruction, inflammatory reactions due to rheumatologic or infectious agents, tumors, etc.) trigger the desire for nausea as part of a defense mechanism, leading to the rapid expulsion of contents from these tissues, and trigger the vomiting reflex.
2. Gag reflex: Stimulation of the back part of the mouth, tongue, and throat (larynx) due to infections, inflammatory reactions, or foreign objects can activate the gag reflex, which may lead to nausea.
3. Stimulation of the central nervous system: The control of gagging and vomiting reflexes is managed by various anatomical regions in the central nervous system. Stimulation of certain areas in the brainstem, due to factors such as drugs, poisoning, toxic products accumulated in the body from liver and kidney diseases, or neurological diseases affecting the brain and spinal cord, can cause nausea and vomiting.
4. Hormonal changes: Significant changes in the levels of various hormones that play vital roles in the body (such as the increased beta-HCG hormone during pregnancy or hormones like estrogen, cortisol, or adrenaline) can cause nausea.
5. Loss of balance: Disruptions in the system that regulates posture and balance in the body (such as improper functioning of the balance organs in the inner ear, vision disturbances, damage to nerve cells responsible for transmitting balance-related signals, etc.) can result in nausea.

How is nausea diagnosed?

The diagnostic approach to nausea involves the physical examinations and medical history taken by a doctor after the patient with this complaint visits a healthcare facility. Through the examination and history-taking process, it can be determined whether the underlying cause of nausea is psychiatric, endocrinological (hormonal), or related to central nervous system disorders such as encephalitis or meningitis.

The first step of the physical examination is to rule out any imbalance in electrolytes (minerals) or fluid loss as the cause of nausea. The patient's fingertips may be examined, and signs such as calluses formed due to contact with stomach acid from self-induced vomiting may be investigated.

Based on the patient's complaints and physical examination findings, the doctor will determine the next steps in the diagnostic approach for nausea on an individual basis. Generally, simple laboratory tests and radiological imaging methods can be used to rule out any underlying significant health problems.

Laboratory tests that may be requested by the doctor include a complete blood count (CBC), electrolytes, erythrocyte sedimentation rate, pancreatic and liver enzymes, pregnancy tests, thyroid hormones, and exposure to chemicals that may cause nausea.

Radiological methods, such as an abdominal X-ray, can be used to evaluate whether there is any obstruction in the digestive system. Endoscopic procedures can be used to examine the esophagus and check for any ulcers or lesions. Abdominal ultrasound (USG) can help evaluate whether there are any issues with the gallbladder, liver, or pancreas.

If the cause of nausea is suspected to be an intracranial mass or lesion, another radiological imaging method called magnetic resonance imaging (MRI) may be used.

How is Nausea Treated?

The treatment of nausea can vary depending on the severity of the complaint and the underlying cause. For example, medications classified as antihistamines and anticholinergics can be prescribed by doctors for nausea caused by motion sickness and seasickness. In cases of reflux disease, which can also cause nausea, medications that regulate stomach acid may be beneficial.

Generally, nausea treatment is divided into two categories. Medications that directly act on the central nervous system to suppress nausea and vomiting are called antiemetics, and they form the first category of medications used for nausea complaints. The other group of medications includes prokinetic drugs, which regulate the movements of the digestive system.

In addition to medication, there are several nausea-relieving applications that can be carried out under the doctor’s advice and guidance:

• Drink clean and cool fluids.
• Eat light and simple foods.
• Avoid fried, fatty, spicy, or overly sweet foods.
• Reduce meal sizes (smaller portions from different food groups to meet the body’s nutritional needs) and eat more slowly.
• Do not consume cold and hot foods consecutively.
• Avoid physical activity immediately after meals.
• Rest.
• Avoid environmental triggers, such as flickering lights that can trigger migraine attacks.
• Adjust the humidity and temperature of the environment.
• Stay away from environments with strong odors, such as perfumes or cooking smells.

Nausea and vomiting are common occurrences after surgeries, radiotherapy, or chemotherapy treatments. In such cases, medications classified as serotonin antagonists may help manage nausea caused by these reasons.

What helps with nausea?

In addition to the above measures, it is possible to prevent nausea from occurring and alleviate it through various individual precautions. The following measures will help eliminate nausea complaints and contribute to maintaining health:

• In cases of intense vomiting along with nausea, it is essential to drink fluids. Replenishing the fluids lost by the body is critical to maintaining health. Moreover, avoid solid foods when feeling nauseous and focus on liquid foods.
• When resuming food intake after nausea, choose easily digestible and non-nauseating foods like bananas, rice, or toast.
• Avoid hot and humid environments, sea trips, strong smells such as perfumes or cooking food, and other factors that can trigger nausea. In cases of motion sickness, taking anti-nausea medication (such as scopolamine or antihistamines) before travel can prevent motion sickness.
• Alter eating habits to ensure a balanced and adequate diet. This means eating frequently but in small amounts, eating slowly and chewing well, and avoiding intense exercise after meals. Additionally, avoid highly spicy or fatty foods.

If your nausea persists despite following the above precautions, consult a healthcare professional for evaluation at the nearest medical facility.