What are medicines?

Medicines are tablets, capsules or liquids that can make people feel better. Within these medicines, there is something called the active ingredient. This is the molecule which acts on your body to make you feel better! They can be molecules extracted from plants or they can be made in a laboratory.

Many medicines work by acting on cells in the body. In this way, they can stop pain or lower blood pressure. Other medicines work by killing bacteria or viruses to stop infections. ​

Over history, medicines have been discovered by scientists trying to cure disease, but some of them happened by chance!

For example: penicillin

You may have heard about the famous scientist Alexander Fleming, or his most famous discovery, an antibiotic called penicillin.​

Without the discovery of penicillin, most of the surgical operations we take for granted today could not take place. Successful treatment of diseases like cancer would not be possible. ​Junior-characters-and-graphicsArtboard-231-(1).png

It all began in 1928 when Alexander Fleming, a scientist at St Mary’s Hospital in London, made an important observation. While growing bacteria in the lab in petri dishes, he noticed that one of his petri dishes had mould on it. But in the area surrounding the mould, the bacteria had been killed.

Fascinated by this, Fleming grew the mould in his lab. He found that the liquid it grew in was deadly poisonous to many types of bacteria.

The mould turned out to be a species called Penicillium and Fleming named the drug penicillin after it. ​

Penicillin meant that doctors could now treat many infections that were previously incurable. Today it remains one of the most important medicines worldwide.


Discoveries like these happen because scientists conduct experiments. Every experiment gives an answer, and often leads to many more questions. It’s like being an explorer, charting unknown territory. ​

Scientists who study medicines are called pharmacologists. They work in the field of pharmacology. If you love science at school, you could be a pharmacologist and make the medicines of the future!​

​Some other questions to think about:​