There are many overlapping terms in medicine. Side effects and adverse effects, for example, being two of the most common. Drugs and medicines, too, are two terms whose meanings overlap – so what is, then, the difference between a drug and a medicine?

To answer this question, we need to ask about purpose – more specifically, what is the purpose of a medicine and what is the purpose of a drug?

The purpose of a medicine is to prevent, alleviate or cure a symptom, ailment or disease state. In other words, the purpose of a medicine is benign; it’s a product produced and regulated to impart a positive medical effect on a patient.

A medicine also tends to have many different components. In addition to the active ingredient, medicines also contain other substances, called excipients, that assist in the formulation and efficacy of that medicine for the patient.

What is a drug, then?

A drug, in contrast to a medicine, can have a positive or negative effect on a patient.

For example, heroin is a drug, in that it’s a substance that causes a specific biological effect. Heroin is not, though, categorised as a substance that “prevents, alleviates or cures a symptom, ailment or disease state”. In that sense, heroin is a not a medicine.

Both drugs and medicines can be poisons, though. This depends on the dose of the drug and/or medicine. As Paracelsus (1493-1541), the founder of toxicology, said, “All things are poisons and nothing is without poison, only the dosage makes a thing not poison”.

To conclude – all medicines are drugs, whereas not all drugs are medicines.

The difference between a drug and a medicine is, then, a slight and simple but significant one. Check back to our pharmacy blog for more posts that examine these types of terminological differences in medicine.