Definition: The dose is a measurement of how much of a specific drug is contained in a medicine. The drug is often very strong, so only a tiny amount (measured in mg - milligrams) will go into a prescribed medication. If the dose is too high, it can be fatal, or the person taking it might be seriously ill. For example, a child might only be given 5mg of a drug, whereas an adult can and might need more. The same is true for animals and birds - the medicine's dose (how many mg) will depend on how much their body needs or can cope with. Doses of medication can be administered in several different ways - intravenously, tablets, nasal spray, etc.