How Felix Hoffmann Invented Aspirin
The 1900 patent for acetylsalicylic acid, the chemical compound that became the world's most common pain reliever, known as Aspirin.
Original patent title: “Acetyl salicylic acid.”
The 1900 patent for acetylsalicylic acid, the chemical compound that became the world's most common pain reliever, known as Aspirin. Granted to FARBENFABRIKEN OF ELBERFELD Co in 1900 with 6 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
This patent describes the chemical process for creating acetylsalicylic acid. It involves reacting salicylic acid with acetic anhydride to produce a stable, usable form of the drug. By acetylating the salicylic acid, the inventorinventorThe person who actually conceived the invention. Listed on the patent regardless of who owns it.Read more → created a compound that was significantly less irritating to the stomach than the raw salicylic acid used previously for pain and inflammation.
The gap
What does this patent NOT cover?
- Does not cover the natural source of salicylic acid found in willow bark.
- Does not cover other non-acetylated derivatives of salicylic acid.
- Does not cover the specific brand name Aspirin, which was a trademarked term.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation was in the acetylation process, which successfully stabilized the compound for human consumption without the severe stomach side effects common to earlier treatments.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Bayer Aspirin
Generic acetylsalicylic acid tablets
Low-dose aspirin for cardiovascular health
Why it matters
The bigger picture
This patent marks the birth of the modern pharmaceutical industry. It transformed how society manages pain, fever, and inflammation, moving medicine from herbal extracts to standardized, mass-produced synthetic chemicals.
Filed
August 1, 1898
Granted
February 27, 1900
Market context
Who's building on this
Companies in this space
Bayer AG continues to be the primary steward of the Aspirin brand. Countless pharmaceutical companies worldwide produce generic versions of the drug now that the original patent has long expired.
Market impact
The patent enabled the creation of a massive global market for over-the-counter pain relief. It established the model for the modern drug industry, where synthetic chemical synthesis replaces traditional herbal remedies.
Claim 1 — Plain English
What this patent covers
This patent describes the chemical process for creating acetylsalicylic acid. It involves reacting salicylic acid with acetic anhydride to produce a stable, usable form of the drug. By acetylating the salicylic acid, the inventor created a compound that was significantly less irritating to the stomach than the raw salicylic acid used previously for pain and inflammation.
The clever bit
The innovation was in the acetylation process, which successfully stabilized the compound for human consumption without the severe stomach side effects common to earlier treatments.
What it does not cover
- Does not cover the natural source of salicylic acid found in willow bark.
- Does not cover other non-acetylated derivatives of salicylic acid.
- Does not cover the specific brand name Aspirin, which was a trademarked term.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Limited data
Citation count
17/40
Early citations
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$14K – $46K
Midpoint $29K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
Hoffmann, F. (1900). How Felix Hoffmann Invented Aspirin (U.S. Patent No. 644,077). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/644077/aspirin-acetylsalicylic-acid
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Felix Hoffmann Invented Aspirin cover?
The 1900 patent for acetylsalicylic acid, the chemical compound that became the world's most common pain reliever, known as Aspirin.
Who owns patent US 644077?
FARBENFABRIKEN OF ELBERFELD Co owns this patent, granted in 1900.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 644077 cited by?
This patent has been cited by 6 later patents that build on its ideas.
What problem does this patent solve?
This patent marks the birth of the modern pharmaceutical industry. It transformed how society manages pain, fever, and inflammation, moving medicine from herbal extracts to standardized, mass-produced synthetic chemicals.
What does this patent NOT cover?
Does not cover the natural source of salicylic acid found in willow bark.
Patent monitoring