Any substance that can be taken orally can be vomited up. Concern about vomiting is an issue of widespread concern. In order to die well, it is imperative that the full (lethal) dose of the drug or substance is digested. It is very important to ensure that vomiting does not occur. Some people are more prone than others to vomiting. Some diseases can cause vomiting. In a minority of cases, vomiting (or fear of vomiting) can be such a problem that oral drugs should not be used.
To make matters worse, end of life drugs and substances are often bitter (or extremely salty). Their strong taste, especially in liquid form, can induce vomiting. Vomiting slows gastric emptying and reduces the effectiveness of the drugs.
To minimize the risk of vomiting and to speed gastric emptying, an anti-vomiting (‘anti-emetic’) drug can be taken as a single dose. Alternatively, this anti-emetic drug can be taken for a set period of time before the consumption of the lethal drug. Indeed, some of the Swiss organisations, who provide oral Nembutal, insist that an anti-emetic be taken prior to the barbiturate.