Recurrent nausea can be a symptom of anything from persistent "stomach flu" to food poisoning, motion sickness, overeating, blocked intestine, drug overdose, concussion, and migraine. Nausea is also the main feature of morning sickness, common during the first trimester of pregnancy. And nausea can be a symptom of such conditions as heart attacks, kidney or liver disorders, central nervous system disorders, (including brain tumors), and some forms of cancer. The tests you’ve gone through should have ruled out any such problems.
Usually described as an uneasy, wave-like feeling in the stomach and head, nausea often includes the urge to throw up but doesn’t always lead to vomiting. Often the timing of nausea suggests the cause. For example, if it occurs shortly after a meal, it can mean food poisoning or a peptic ulcer.
You may be able to prevent nausea by eating several small meals throughout the day instead of three big ones. Be sure to eat slowly and avoid fried, greasy or sweet foods that are hard to digest. If the smell of hot or warm foods triggers your nausea, be sure that your foods are cold or at room temperature. Lying down after eating and keeping your head elevated about 12 inches above your feet can sometimes help.
If you feel nauseated when you wake up in the morning, eat some crackers before getting out of bed. In addition, a high protein snack at bedtime can help prevent nausea the next morning. Drinking liquids between (instead of during) meals can also help. Be sure to drink at least six to eight 8-ounce glasses of water a day to prevent dehydration.
My top remedy for nausea is ginger in any form. You can mix a half teaspoon of ginger powder in a glass of water and drink or take two capsules of powdered ginger. Even ginger snaps, ginger candy and ginger ale can help to quell mild nausea. If you can't find ginger ale that actually contains ginger, you can make your own with ginger syrup and seltzer water.
To prevent nausea due to seasickness I use acupressure wristbands, the modern version of an old Chinese fisherman's remedy of stimulating the acupressure points that control nausea. They have plastic pegs that press on acupressure points on the inner surfaces of the wrists, and this may help for generalized nausea as well. Proper placement of the wristbands is critical so follow package directions carefully.
Andrew Weil, M.D.