The causes of nausea are many. One organization listed 700 in 2009.

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 the food.

Medications

Most medications can potentially cause nausea. Some of the most frequently associated include chemotherapy regimens and general anaesthetic agents .

Pregnancy

Nausea or " morning sickness" is a common symptom of pregnancy. In the first trimester nearly 80% of women have some degree of nausea. Pregnancy therefore should be considered in any women of child bearing age.

Disequilibrium

A number of conditions involving balance such as motion sickness and vertigo can lead to nausea and vomiting.

Potentially serious

While most causes of nausea are not serious some serious causes do occur. These include: diabetic ketoacidosis, surgical problems ( pancreatitis, small bowel obstruction, meningitis, appendicitis, cholecystitis), Addisonian crisis, Choledocholithiasis (from gallstones) and hepatitis among others.

Often no investigations are needed, however basic lab tests may be appropriate.

If dehydration is present, rehydration with oral electrolyte solutions is preferred.

Medications

Dimenhydrinate (Gravol) is an inexpensive and effective medication for preventing postoperative nausea and vomiting. Meclizine is another antihistamine antiemetic. In certain people cannabinoids may be effective in reducing chemotherapy associated nausea and vomiting. Ondansetron (Zofran) is effective for nausea and vomiting but is expensive.

Medical marijuana may be prescribed where allowed for certain indication.

While short-term nausea and vomiting are generally harmless, they may sometimes indicate a more serious condition. When associated with prolonged vomiting, it may lead to dehydration and/or dangerous electrolyte imbalances.

Nausea and or vomiting is the main complaint in 1.6% of visits to family physicians in Australia. However only 25% of people with nausea visit their family physician.