Depends a lot on the reason for the nausea and vomiting. If it's an intelligent thing your body is doing (i.e. there is a good reason for expelling what's down there - food poisoning, drunkenness, mild travel sickness), encouraging the vomiting is the best way to go. Then it's all over as quickly as possible. If the nausea/vomiting has nothing to do with the food/drink in the stomach and it's definitely safe for the food/drink to stay where it is, then antacids for nausea and anti-vomiting pills in cases of mild vomiting is the way to go. If someone is in a bout of severe vomiting there's not much you can or even should do except watch the person and if it continues to the point of being dangerous (i.e. continuing even after lots and lots of dry retching and showing no signs of stopping) and then you just have to take them to the hospital.
If you know that it's going to happen and it's definitely goign to be safe for the food/drink to stay in the stomach, there are anti-nausea/vomiting pills you can get from your pharmacist.
If it's not safe for the food/drink to stay in the stomach and you repress the vomiting - like if you take anti-nausea pills before getting ridiculously drunk - then you could kill yourself by accident.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.