Aspirin White willow (Salix alba). © Kurt Stueber, 2007.

By Professor Tilli Tansey
Wellcome Trust Centre for the History of Medicine, UCL.

What is aspirin?

Aspirin is derived from a chemical called Salicin, which is found naturally in willow bark. Aspirin was first marketed by the German pharmaceutical company Bayer in 1899, but the pain alleviating effects of willow bark were documented by Hippocrates over 2,000 years earlier. In the eighteenth century the English clergyman Edmund Stone used infusions of willow bark to relieve fever and pain amongst his parishioners, and published his results in Philosophical Transactions of the Royal Society.  However, these early ‘raw’ preparations caused severe irritation of the mouth, oesophagus and stomach. The German chemist Felix Hoffman is commonly credited with modifying the active ingredient to make aspirin.

What does it do?

Aspirin is largely used to relieve pain, fever and inflammation, but it has numerous other uses - taken daily it can protect against heart disease, strokes, Alzheimer's disease and even certain types of cancer. Over 100 billion aspirin tablets are consumed every year.

How does it work?

British scientist Sir John Vane FRS discovered that aspirin inhibits the production of several naturally occurring substances called ‘prostaglandins’ which are associated with a number of mechanisms in the human body, including pain pathways and blood clotting.  He shared the Nobel Prize for this discovery in 1982. However not all aspirin's mechanisms are known.

What are the dangers of aspirin use?

Many preparations of aspirin can irritate the stomach and in severe cases cause bleeding and ulceration. People taking regular preventative doses of aspirin take a formulation that does not cause such irritation. Reye's syndrome, a rare disorder that can cause delirium and even death, has been associated with the consumption of aspirin by young children.


Edmund Stone’s account of the use of willow bark in curing fevers is highlighted in Trailblazing, the interactive timeline launched to celebrate the Royal Society’s 350th anniversary: