The first medicines were discovered in nature from natural sources such as plants, herbs, roots, fungi and vines. For many years, until the mid-nineteenth century nature's medicines were the only medicines available to treat pain in humans. The oldest drug documented to treat pain was Opium which was extracted from unripe pods of poppy flowers.

Today, many medicines are made in laboratories using extracts from natural sources whilst some medicines can be made by man and are called synthetic medicines. Today, medicines are manufactured in laboratories according to strict protocols, where medicines undergo controlled testing to meet standards of safety and efficacy. Medicines are usually registered in a country by the legal authorities before people are allowed to use them.

Medicines are made in many forms such as tablets, capsules, injections, syrups, creams and ointments. These are known as dosage forms. A dosage form is a vehicle used to deliver a medicinal drug to the body in a specific dose (or amount). Different dosage forms are made to suit different patients and different situations. For example, syrups are made for people who cannot swallow big tablets such as babies, children or very old people.

Medicines can be grouped together into different classes according to their chemical type of their active ingredient or the manner in which they are used to treat a medical condition. Examples of drug classes are: (i) antibiotics which kill bacteria and (ii) antipyretics which are used to treat fever.

Some medicines can only be acquired on a prescription. A prescription is a document on which medicine is ordered. A prescription is usually written by an authorised prescriber such as a doctor or pharmacist who can prescribe medicines in accordance with the law of the country in which they work.

Medicines are becoming more advanced everyday. An example of this is the field of nanotechnology where medicines are being developed to be more effective and to reach specific sites in the body.