In 1897, a German chemist while trying to ease his father’s rheumatic pains accidently developed a drug still widely used as an over-the-counter medication around the world: How did Felix Hoffmann invented Aspirin?

In 1897, a German chemist while trying to ease his father’s rheumatic pains accidentally developed a drug still widely used as an over-the-counter medication around the world. The chemist was Felix Hoffmann, who worked at Bayer in Germany. He was trying to modify chemical compounds used in medicine. His work led to acetylsalicylic acid, which Bayer later named Aspirin. The drug came from salicylic acid, a substance known for pain and fever relief but also linked to stomach irritation. Hoffmann’s work took place during a period when chemists were changing natural substances to create medicines. The same two-week period also produced heroin.

How Felix Hoffmann’s work at Bayer led to aspirin?

In 1897, a German chemist while trying to ease his father’s rheumatic pains accidentally developed a drug still widely used as an over-the-counter medication around the world. Felix Hoffmann was born in 1868 in Ludwigsburg, Swabia, Germany. His father was a manufacturer. Hoffmann first worked in pharmacies in different German towns and cities.


He later studied chemistry and pharmacy at the University of Munich. He completed his studies in 1893. One of his professors was Adolf von Baeyer. Baeyer later received the Nobel Prize in Chemistry in 1905 for his work related to the synthesis of dyes.

Hoffmann joined the pharmaceutical research department of the Bayer Company in Elbersfeld after receiving a recommendation from Baeyer. At Bayer, Hoffmann worked on chemical changes that could alter the properties of substances used for medical purposes.

Why chemists were modifying existing substances?

During the late 19th century, chemists were looking for ways to create medicines rather than only obtain active substances from plants and other natural materials. One method involved changing substances that were already known to have effects on the human body. Another method involved working with organic compounds that were produced as products or by-products of the synthetic dye industry.

The synthetic dye industry had expanded during the 19th century. Germany had become an important center for this chemical industry. Hoffmann was part of this period of research. In the summer of 1897, he was adding an acetyl group, written chemically as CH3CO, to different molecules. The purpose was to change substances in the hope of increasing their medical effect or reducing their harmful effects.

Bayer had already used this approach with other medicines. Phenacetin, introduced in 1888 as a fever-reducing medicine, was an acetylated form of p-nitrophenol. P-nitrophenol itself was a by-product of blue dye manufacturing and had no useful medical application.

Bayer also introduced Tannig in 1894 as an antidiarrheal medicine. It was produced by acetylating tannic acid, a substance connected with materials used in leather tanning. Hoffmann later recalled that Bayer chemists often worked through experience and instinct. They spoke about having a “good nose” for finding substances that could become medicines.

The connection between salicylic acid and aspirin

Salicylic acid was already known before Hoffmann began his work. People had used willow bark and related plant materials for pain and fever for centuries. Salicylic acid was later isolated from willow bark by several chemists during the early 19th century.

In 1859, Hermann Kolbe determined the chemical structure of salicylic acid and synthesized it. In 1874, the Heyden Company near Dresden began manufacturing synthetic salicylic acid. Synthetic production made the substance less expensive than obtaining it directly from willow bark.

However, salicylic acid had a problem. It could irritate the stomach. Some patients could not tolerate it. The commonly repeated story says Hoffmann wanted to find a substance that could help his father with rheumatic pain without the same problem. Hoffmann acetylated salicylic acid. The chemical reaction produced acetylsalicylic acid. This substance later became known as aspirin.

How acetylsalicylic acid became Aspirin?

After Hoffmann produced acetylsalicylic acid, Heinrich Dreser, who headed Bayer’s pharmaceutical laboratory, tested the substance for toxicity on himself. Dreser then arranged animal experiments. Human testing followed. Patients at a hospital in Hall an der Saale received acetylsalicylic acid.

The substance was eventually given the name Aspirin. The name came from the letter A, referring to acetyl, and “spirin,” which was connected to Spirea, the genus name for shrubs that can also provide salicylic acid. Aspirin later became an over-the-counter medicine and continued to be sold more than a century after Hoffmann’s work.

Was Felix Hoffmann the only person behind aspirin?

The story of aspirin has been debated. Evidence has emerged suggesting that Arthur Eichengrün, another Bayer employee, may have played a role in the development of aspirin. Some accounts suggest that Eichengrün was left out of the story that became common from the 1930s. One explanation offered for this omission is that Eichengrün was Jewish.

Therefore, the historical record around the invention of aspirin is not limited to Hoffmann alone. The role of other Bayer researchers remains part of the discussion about how aspirin was developed.

Why Bayer could not secure a German patent?

Bayer recognized that acetylsalicylic acid could become a major medicine. The company applied for a German patent. The application was rejected. The reason was that acetylsalicylic acid had already been synthesized before Hoffmann’s work. A French chemist and later a German chemist had produced the compound.

However, their versions were not produced in a pure and stable form. Bayer therefore moved ahead with the substance and marketed aspirin in different countries. In the United States, Bayer obtained a patent in 1900. This gave the company control over manufacturing the drug in the country until 1917.

How aspirin became an over-the-counter medicine?

Bayer’s American operations later became part of events connected to the First World War. In 1919, Bayer’s American plants were sold as part of reparations imposed on Germany after World War I. Sterling Products of Wheeling, West Virginia, invested $3 million in Bayer’s US drug properties.

Sterling later failed to protect the trademark status of the word aspirin. As a result, aspirin became part of the over-the-counter medicine market in the United States and other countries. More than 100 years after its development, aspirin remains in use for purposes that extend beyond what its original developers had expected.

SmithKline Beecham later acquired Sterling’s worldwide over-the-counter pharmaceutical business. It subsequently sold the US portion, including aspirin, back to Bayer for $1 billion.

What aspirin’s history tells us?

The development of aspirin shows how medicine and chemistry were changing during the late 19th century. Chemists were not only extracting substances from plants. They were modifying existing molecules and testing whether chemical changes could produce substances with different medical properties.

Felix Hoffmann’s work at Bayer became part of this transition. Aspirin came from the chemical modification of salicylic acid. Its development also shows why the history of scientific discoveries can involve several researchers and earlier experiments.

The story also has an unusual connection with heroin. Both substances were synthesized by Hoffmann at Bayer during the same two-week period in 1897. Their histories later moved in different directions. Aspirin became an over-the-counter medicine used around the world, while heroin became a controlled and banned substance in most countries.

Felix Hoffmann life

• Felix Hoffmann studied chemistry and pharmacy at the University of Munich.
• He joined Bayer’s pharmaceutical research department in Elbersfeld.
• In 1897, he worked on acetylating different chemical compounds.
• He acetylated salicylic acid to produce acetylsalicylic acid.
• Acetylsalicylic acid was later named Aspirin.
• Salicylic acid had been used for pain and fever but could irritate the stomach.
• Heinrich Dreser tested acetylsalicylic acid for toxicity and arranged further experiments.
• Bayer marketed aspirin around the world.
• Bayer obtained a US patent in 1900 and held it until 1917.
• Sterling Products acquired Bayer’s US drug properties in 1919.
• Sterling later failed to protect aspirin as a trademark.
• Aspirin became an over-the-counter medicine.
• Arthur Eichengrün has also been credited by some historical accounts with a role in aspirin’s development.