Meaning of Feeling Nauseous
Nausea or feeling nauseous are terms used to describe the unpleasant sensation of wanting to vomit. It usually precedes vomiting but may occur on its own without any vomiting. Nausea is said to be the conscious perception of a subconscious process that leads to vomiting. As is explained under What is Vomiting, direct stimulation of the vomiting centers in the medulla or stimulation via the chemoreceptor trigger zone (CTZ) will initiate the vomiting process. Nausea may be the conscious perception of this stimulation or simultaneous excitation of surrounding areas in the medulla.
Nausea may be triggered by impulses from the upper gastrointestinal tract due to :
- Food poisoning (microbial toxins)
- Infections (gastroenteritis)
- Chemical poisoning
- Slow or rapid gastrointestinal motility
- Liver, gallbladder and pancreas disorders
- Gastointestinal pain related to trauma, inflammation, infection, ulcers
Causes of Nausea
Although vomiting causes a forceful expulsion of the upper gastrointestinal contents, both nausea and vomiting may be triggered by a range of other stimuli that does not involve the gut in any way.
- Drugs – pharmaceutical or narcotic
- Excessive tobacco consumption/nicotine intake
- Emergency contraceptives (‘morning after’ pill)
- Shock, fear (vasovagal)
- Central Nervous System Disorders
- Head injury – closed head trauma, cerebral hemorrhage
- Raised intracranial pressure
- Central nervous system infections like meningitis, encephalitis
- Inner ear – labyrinthitis
- Systemic Conditions
- Low blood sugar levels
- Diabetic ketoacidosis
- Addison’s disease
- Liver failure
- Kidney failure
- Advanced stages of medical conditions (independent of medication) :
Nausea After Food
Nausea after eating typically presents immediately after or within 20 to 30 minutes after eating. It can last anywhere from less than 30 minutes to up to an hour. Very rarely, does it start 1 hour or more after eating and in these instances, it may not be related to eating. The nauseous feeling may vary in intensity and can be acute or chronic (recurrent, persistent, constant).
Most cases of nausea after eating are associated with gastrointestinal causes. However there are some psychiatric and systemic causes which may need to be considered.
Most conditions that affect the upper gastrointestinal tract (esophagus, stomach, duodenum) may cause nausea after eating. The presence of concomitant signs and symptoms may be necessary to identify a possible cause.
- Acute gastroenteritis(infection)
- Gastric pain
- Occasional vomiting
- Loss of appetite
- Aggravated by alcohol, certain drugs, caffeine and spicy foods
- Gastroesophageal reflux disease(GERD)
- Dyspepsia(indigestion) – non-ulcer or functional dyspepsia
- Gallbladder disease
- Nausea worse after eating fats – symptoms similar to dyspepsia
- Severe upper middle abdominal pain worse after eating, especially with gallstones
- Gastrointestinal obstruction
- Projectile vomiting
- Gastric outlet obstruction – vomit not stained with bile
- Obstruction distal to (after) the pylorus – green to bright yellow bile vomit
- Abdominal distension
- Intestinal spasms (colicky pains)
- Abdominal distension
- Bloated (feeling of fullness after a few bites)
- Fluctuating blood sugar levels
- Lack of appetite
Nausea after eating may also be due to pancreatitis, hepatitis or appendicitis.
In infants, nausea cannot be reported but vomiting following eating should be considered seriously if it occurs after every feeding and there is failure to thrive. Causes like pyloric stenosis, malrotation, Hirschsprung’s disease an intussusception need to be investigated.
- Psychogenic nausea after eating may be seen when a person considers the food being consumed as repulsive. Sometimes this is also evident in anorexics who are forced to eat.
- Pregnancy – nausea is common after eating, especially in the mornings.
- Cancer treatment – chemotherapy, radiation therapy – often associated with gastritis.
- Angina may result in chest pain and nausea after eating.
- Diabetes mellitus (sugar diabetes) – nausea after eating due to elevation of blood sugar levels which peaks about 90 minutes after eating. Nausea when blood sugar levels are low may also be reported.
- Ingestion of poisons may cause nausea almost immediately after eating or drinking the toxic substance.