Nausea and vomiting can be triggered by many factors, including:

• Gastroenteritis. This inflammation of the lining of the stomach and intestines is typically caused by a viral infection or bacteria from contaminated food or water. In addition to nausea and vomiting, you may have watery diarrhea and abdominal cramps.
• Headache or inner ear disturbance. An intense headache, such as a migraine, can cause nausea and vomiting. An inner ear disturbance, such as motion sickness, also can make you queasy.
• Medical treatment. Vomiting is often associated with anti-cancer drugs and radiation therapy.
• Toxins. High levels of toxins in your blood ¡ª including alcohol, nicotine and drugs such as antibiotics ¡ª can cause nausea and vomiting.
• Hormones. The hormonal changes of early pregnancy can make you nauseated and lead to vomiting, as can the surges in hormones that often occur in periods of intense stress. Problems with the thyroid gland ¡ª producing either too much thyroid hormone or not enough ¡ª also can result in nausea.
• Peptic ulcers. Peptic ulcers are open sores that develop on the lining of the stomach, upper small intestine or esophagus. The classic symptom is burning pain anywhere from your navel to your breastbone, but peptic ulcers may cause nausea and vomiting as well. Many peptic ulcers are caused by the bacterium Helicobacter pylori (H. pylori).
• Gallstones. Gallstones are solid deposits of cholesterol or calcium salts that form in your gallbladder or nearby bile ducts. Sometimes, gallstones cause nausea, vomiting, indigestion and abdominal pain.
• Pancreatitis. Pancreatitis is a condition in which digestive enzymes attack the pancreas rather than break down food in the small intestine. The condition causes mild to severe abdominal pain, often accompanied by nausea, vomiting and fever.

Self-care measures

If you're feeling queasy, these suggestions may help:

• Take it easy. Activity may make nausea worse.
• Stay hydrated. Suck on ice chips or frozen fruit pops. Take small sips of water, weak tea, clear soft drinks, noncaffeinated sports drinks or broth. Drinks containing sugar may calm your stomach better than other liquids.
• Avoid food odors. Don't cook. Avoid restaurants and other places likely to smell like food.
• Eat bland foods. Start with easily digested foods such as gelatin, crackers and toast. When you can keep these down, try cereal, rice and fruit. Avoid fatty or spicy foods.