What is Nausea or Vomiting?
Nausea is an uneasiness of the stomach that often comes before vomiting. Vomiting is the forcible voluntary or involuntary emptying (throwing up) of stomach contents through the mouth.

Nausea and vomiting are not diseases, but they are symptoms of many conditions such as:

1) Motion sickness or seasickness
2) Early stages of pregnancy (nausea occurs in approximately 50% to 90% of all pregnancies; vomiting in 25% to 55%)
3) Medication-induced vomiting
4) Intense pain
5) Emotional stress (such as fear)
6) Gallbladder disease
7) Food poisoning
8) Infections (such as the stomach flu)
9) Overeating
10) A reaction to certain smells or odors
11) Heart attack
12) Concussion or brain injury
13) Brain tumor
14) Ulcers
15) Some forms of cancer
16) Bulimia or other psychological illnesses
17) Gastroparesis or slow stomach emptying (a condition often seen in people with diabetes)
18) Ingestion of toxins or excessive amounts of alcohol

The causes of vomiting differ according to age. For children, it is common for vomiting to occur from a viral infection, food poisoning, milk allergy, motion sickness, overeating or feeding, coughing, or blocked intestines and illnesses in which the child has a high fever.

The timing of the nausea or vomiting can indicate the cause. When appearing shortly after a meal, nausea or vomiting may be caused by food poisoning, gastritis (inflammation of the stomach lining), an ulcer, or bulimia. Nausea or vomiting one to eight hours after a meal may also indicate food poisoning. However, certain food borne bacteria, such as salmonella, can take longer to produce symptoms.

Adopted from webmd.com