When urine served as toothpaste and soap in ancient Rome

A use that shocks our modern sensibilities

It's hard today to imagine brushing your teeth with urine. And yet in ancient Rome, this practice was neither exceptional nor shameful. Human urine, rich in ammonia, was considered a valuable cleaning product, used both to whiten teeth and to clean wool clothing. What seems repulsive to us today followed, two thousand years ago, a perfectly rational chemical logic for its time.

This use was neither marginal nor shameful: it was woven into the Roman urban economy, with collection networks, dedicated taxation, and well-established industrial uses. Understanding this practice helps us grasp just how pragmatic — and at times surprising — the Romans' approach to hygiene and resource recycling in their urban environment really was.

The chemical basis of an ancient practice

The scientific reason behind this use lies in the composition of urine, which naturally contains a significant amount of ammonia after a period of fermentation. This chemical compound has recognized degreasing and whitening properties, capable of dissolving stains and eliminating certain organic residues on fabrics or teeth.

The Romans obviously knew nothing of modern chemistry or the exact formula for ammonia, but through observation and trial and error, they had empirically identified this substance's effectiveness for maintaining their laundry and personal hygiene. This practical knowledge was passed down from generation to generation for centuries.

The little-known trade of the Roman fuller

At the heart of this practice were the fullers, craftsmen specialized in cleaning, degreasing, and whitening wool garments. Their workshop, called a fullonica, was an essential step in the Roman textile production chain, indispensable for making fabrics presentable before sale or public wear.

Fullers used large vats where garments were soaked in a mixture containing fermented urine, then trampled underfoot to work the product thoroughly into the wool fibers. This process, however unappealing it looks from our vantage point today, produced remarkably clean, whitened fabrics that met the aesthetic standards of Roman society.

Collection organized at the scale of the city

To supply these workshops, public jars were placed in the streets of Rome, allowing passersby to relieve themselves there, with the contents later collected by fullers or specialized collectors. This collection system reflects a genuine logistical organization built around this resource, woven into the daily functioning of the city.

This collection was not a minor detail: it represented an economic flow significant enough to justify specific regulation and taxation, proof that this activity held a recognized place in the Roman urban economy, on par with more conventional trades.

A tax on an unexpected product

One of the best-known episodes in this history involves the emperor Nero, or according to some sources his predecessor Vespasian, who reportedly introduced a tax on the trade of urine collected from public jars. This fiscal decision, which may raise a smile today, shows just how real and recognized an economic value this resource held in the eyes of imperial power.

The Latin phrase "pecunia non olet," meaning "money doesn't smell," is traditionally linked to this fiscal episode. It perfectly sums up the pragmatic philosophy of Roman authorities: no matter where revenue comes from, as long as it fills the state's coffers, its nature poses no moral or political problem.

A historical anecdote with sometimes debated sources

While the urine tax anecdote is widely repeated in popular culture and history books, specialist historians point out that the exact ancient sources attributing this measure to one emperor or another remain somewhat open to interpretation. What does remain certain, however, is the very real existence of an organized trade around this resource in ancient Rome.

This historiographical nuance takes nothing away from the interest of the anecdote: it illustrates how the Romans approached available resources with an economic pragmatism that would almost feel modern, at a time when recycling wasn't yet a theorized concept.

The poet Catullus's biting testimony

The Latin poet Catullus, known for his sharp, often mocking verse, left a valuable account of this practice by ridiculing some of his contemporaries who brushed their teeth with Portuguese urine, reputed to be more concentrated in ammonia than the local variety. This poetic mockery remains today one of the most cited literary sources on this ancient hygiene custom.

This specific reference to a particular geographic origin suggests that Romans held some form of hierarchy or reputation associated with the quality of the urine used, somewhat like how we might distinguish different grades of cleaning products today based on their origin or composition.

A dental practice with real but questionable effects

From a purely chemical standpoint, the ammonia contained in urine did indeed have properties capable of whitening teeth and neutralizing certain bacteria responsible for bad breath. This relative effectiveness explains why the practice could persist for centuries despite how unappealing it looks through a contemporary lens.

Historians of ancient medicine point out, however, that this method, while producing a genuine whitening effect, was not without risk to tooth enamel over the long term, given the chemical aggressiveness of concentrated ammonia on fragile dental tissue.

A different conception of modesty and disgust

This practice reveals just how much thresholds of disgust and modesty vary across eras and cultures. What seems unacceptable to us today amounted, in the Roman context, to a pragmatic and rational management of available bodily resources, without the negative symbolic weight that we instinctively attach to it today.

Romans lived in an urban environment where the management of bodily waste occupied a far more visible and integrated place in daily life than in our contemporary societies, marked by a strong privatization and systematic concealment of these bodily realities.

A parallel with other ancient hygiene practices

This use of urine was just one example among other Roman hygiene practices that seem surprising to us today, such as the common use of sponges on sticks in public latrines or communal baths where water was not systematically changed between users. These practices reflect a conception of the body and of cleanliness very different from our own.

Placed back in their historical context, these habits do not really reflect a lack of hygiene, but rather a coherent system adapted to the scientific knowledge and resources available at that particular period in human history.

The remains of fuller workshops

Archaeological excavations carried out notably in Pompeii and Ostia have uncovered remarkably well-preserved remains of fuller workshops, complete with their soaking vats and specific installations. These finds give historians a concrete, tangible understanding of how this industry functioned day to day in Roman cities.

These archaeological sites also help us better understand the spatial organization of this activity within the urban fabric, with workshops often located on the outskirts of residential neighborhoods, likely because of the characteristic odors associated with this type of trade.

A source of wonder for museum visitors

Today, these remains are among the elements that spark the most curiosity, and sometimes astonishment, among visitors to archaeological museums specializing in ancient Rome. This practice, however surprising it may seem to modern sensibilities, offers an excellent entry point for illustrating the practical creativity of ancient societies in the face of urban hygiene challenges.

Museum curators often highlight the educational value of this anecdote for engaging the public, especially younger visitors, in a broader reflection on how hygiene and cleanliness standards have evolved throughout human history.

A practice found across the entire Mediterranean basin

This use of urine for hygiene and cleaning purposes was not confined to the city of Rome alone. Similar traces have been identified in several regions of the Mediterranean basin, suggesting that this practice reflected a body of know-how shared by several ancient civilizations facing the same technical constraints and the same limited resources.

This geographic spread reinforces the idea that reliance on natural ammonia answered a universal practical logic rather than a purely Roman cultural quirk. Several ancient peoples independently developed similar methods for exploiting this organic resource.

A gradual disappearance with the arrival of new processes

This practice gradually disappeared with the emergence of new cleaning processes and new chemical substances that were more effective and, above all, more socially acceptable. The evolution of hygiene standards over the centuries eventually relegated this ancient method to the status of historical curiosity rather than everyday practice.

Historians of daily life in antiquity note that this transition did not happen overnight, but unfolded over several centuries, as new bleaching and cleaning techniques emerged in different regions of the Roman Empire and beyond.

A useful reminder about the relativity of norms

This story of urine used as toothpaste in ancient Rome forcefully reminds us that our own hygiene and cleanliness standards, which we often consider universal and definitive, are actually the product of a particular historical and scientific evolution, one that is itself bound to keep changing in the future.

What Romans perceived as a practical, rational solution seems repulsive to us today, just as some of our current practices will likely seem strange, even incomprehensible, to future generations who will look back on our era with the same historical hindsight we now bring to antiquity.

An anecdote that keeps fascinating

More than two thousand years after the fall of the Roman Empire, this anecdote continues to fascinate and feed popular curiosity about ancient history, proof that the most unusual details of ancient daily life often remain more memorable than the grand political and military narratives traditionally taught in school textbooks.

By Maxime Marquette, columnist

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I am not a journalist but a columnist and analyst. My expertise lies in observing and analysing the geopolitical, economic and strategic dynamics that shape our world. My work is to take political strategies apart, to understand global economic movements, to put the decisions of international actors in context and to offer analytical perspectives on the changes that are redefining our societies.

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