Nausea is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It occasionally precedes vomiting. A person can suffer nausea without vomiting. Nausea is a non-specific symptom, which means that it has many possible causes. Some common causes of nausea are motion sickness , dizziness, migraine, fainting , gastroenteritis (stomach infection) or food poisoning . Side effects of many medications including cancer chemotherapy, nauseants or morning sickness in early pregnancy. Nausea may also be caused by anxiety , disgust and depression.
Medications taken to prevent and treat nausea are antiemetics . The most commonly prescribed antiemetics are promethazine , metoclopramide and ondansetron .
Food poisoning:
Food poisoning usually causes an abrupt onset of nausea and vomiting one to six hours after ingestion of contaminated food and lasts for one to two days. It is due to toxins produced by bacteria in food.
Medications:
Many medications can potentially cause nausea. Some of the most frequently associated include cancer and systemic chemotherapy regimens and general anaesthetic agents.
Pregnancy:
Nausea or " morning sickness " is common during early pregnancy but may occasionally continue into the second and third trimesters. In the first trimester nearly 80% of women have some degree of nausea. Pregnancy should therefore be considered as a possible cause of nausea in any women of child bearing age. While usually it is mild and self-limiting severe cases known as hyperemesis gravidarum may require treatment.
Disequilibrium
A number of conditions involving balance such as motion sickness and vertigo can lead to nausea and vomiting.
Stress and depression
Nausea may be caused by stress and depression . Potentially serious While most causes of nausea are not serious, some serious causes do occur. These include: Intercranial Pressure secondary to head trauma or hemorrhagic stroke, diabetic ketoacidosis , brain tumor , surgical problems, heart attack, pancreatitis, small bowel obstruction , meningitis, appendicitis , cholecystitis, Addisonian crisis, Choledocholithiasis (from gallstones) and hepatitis , as a sign of carbon monoxide poison and many others.
If severe anxiety appears to be the cause of nausea, then a short course of an anti-anxiety medication such as lorazepam (Ativan) may be all that is needed. If pain is present the nausea can be caused by pain or by opioids used to treat the pain. These may include codeine, hydrocodone, meperidine, morphine,
oxycodone, hydromorphone, or fentanyl. These drugs cause nausea in several ways. They may stimulate the eighth cranial nerve which causes vestibular effects such as dizziness or they may stimulate what is called the Chemo Receptor Trigger zone (CTZ) which in turn
stimulates the Vestibular Apparatus in the brain which in turn causes nausea and perhaps vomiting. In addition, opioids may slow gastric emptying, causing constipation, which is often accompanied by nausea. If changing opioids does not abate the symptom then addition of antiemetics becomes necessary? Choice of treatment then is indicated by causation. If pain and anxiety are present then drugs or doses need to be increased.
If nausea is caused by movement then adding an over the counter medication such as meclizine is indicated; if constipation is the cause then a laxative is in order; if these fail then often addition of metacloperamide (to stimulate gastric emptying) and haloperidol in very low doses (to block stimulation of the CTZ) will often give relief. If the nausea is very acute, followed by vomiting, in an otherwise healthy
person, it is often best to with hold food and then give clear liquids at least in the first 24 hours may be best as the nausea/vomiting may be a defense mechanism where the body is ridding itself of a toxin. If this is done, however, the age and general condition of the person has to be considered. An infant or small child can become dangerously dehydrated in 2-3 hours, while a healthy 21year old can withstand the fluid loss for somewhat longer.
Note that there is no all purpose antiemetic. Successful treatment depends on identification of cause.
Treatment
If dehydration is present due to loss of fluids from severe vomiting, rehydration with oral electrolyte solutions is preferred. If this is not effective or possible, intravenous rehydration may be required.
NIH Medline recommends drinking clear fluids, sitting quietly and eating bland foods. Medline recommends you call a doctor if you: Cannot keep any food or liquid down, Vomit 3 or more times in 1 day.
Ondansetron (Zofran) is effective for nausea and vomiting. Pyridoxine or metoclopramide are the first line treatments for pregnancy related nausea and vomiting. Many consider medical marijuana to be an effective herbal remedy for nausea.
Several studies have demonstrated the therapeutic effects of cannabinoids for nausea and vomiting in the advanced stages of illnesses such as cancer and AIDS.
Ginger has also been shown to be potentially effective in treating several types of nausea.
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