Treating the bubonic plague in medieval and early modern Europe meant working with almost no understanding of what actually caused the disease. Physicians relied on ancient Greek medical theory, religious ritual, and folk remedies that ranged from elaborate herbal concoctions to placing live chickens on infected sores. Some of these approaches were genuinely harmful, others were surprisingly forward-thinking, and almost none of them worked against the bacterium we now know as Yersinia pestis.
The Medical Theories Behind the Treatments
Every plague treatment of the era grew out of one or more dominant ideas about what caused disease. The most influential was the theory of the four humors, inherited from ancient Greek medicine, which held that the body contained four fluids: blood, yellow bile, black bile, and phlegm. All illness resulted from an imbalance among these fluids, and the physician’s job was to restore equilibrium. This framework drove treatments like bloodletting, purging, and strict dietary advice for centuries.
Alongside the humoral model sat the miasma theory, which blamed disease on foul-smelling air rising from rotting organic matter, open sewage, swamps, and piles of corpses. Because the plague seemed to strike in crowded, filthy areas, this explanation felt intuitive. It led authorities to order the burning of sulfur and juniper berries in the streets to “purify” the atmosphere, and it justified the elaborate scented masks later worn by plague doctors. A third explanation was purely religious: the plague was God’s punishment for sin, and the appropriate response was prayer, fasting, and penance.
Notably, some observers landed on a fourth idea that turned out to be closer to reality. Even without knowledge of bacteria, physicians in northern Italy recognized that the disease seemed to spread from person to person and through traded goods. This observation of contagion, rather than bad air, became the foundation for quarantine systems.
Bloodletting and Lancing Buboes
The most common hands-on treatment was bloodletting. Physicians believed that drawing blood from the body would remove excess or corrupted humors and restore balance. The location of the cut mattered. Medical reference books from around 1410 included diagrams of a “vein man” showing exactly where to open a vein depending on the patient’s symptoms. Christian European physicians generally drew blood in small amounts and were cautious about which side of the body to cut, warning that drawing blood from the wrong side could pull corrupt humors across the heart and spread the infection. Physicians in the Islamic world took a different approach, bleeding patients until they felt faint, believing larger volumes needed to be removed.
The painful, swollen lymph nodes called buboes received direct treatment as well. Physicians applied poultices of figs, cooked onions, yeast, and butter to soften the swellings. Once a bubo was soft enough, it would be lanced open with a blade, drained, and then cauterized with heat. Some practitioners used a cupping glass, a heated glass vessel placed over the bubo to draw fluid to the surface before slicing it open. The logic was that the bubo contained poisoned matter that needed to leave the body. This was agonizing for the patient, but draining an infected lymph node may have occasionally provided some limited relief.
Theriac and Other Internal Remedies
The most prestigious medicine available during plague outbreaks was theriac, also known as treacle. This was an extraordinarily complex preparation with roots stretching back to antiquity. The Roman physician Galen described a version called “Galene” containing 55 separate ingredients, including dried viper flesh, opium (listed as “poppy juice”), myrrh, cinnamon, black and white pepper, long pepper, honey, beaver secretion, roasted copper, bitumen, and dozens of herbs. An older related formula, Mithridatium, contained 41 ingredients and swapped in lizard flesh instead of viper.
These formulas barely changed over the centuries. The 1746 London Pharmacopoeia still listed theriac with 61 ingredients and Mithridatium with 45, virtually identical to Galen’s recipes from 1,500 years earlier. Alongside theriac, physicians prescribed London treacle and diascordium, a preparation based on water germander. Medicines were often mixed with honey to make them palatable, forming pastes called electuaries, or blended into syrupy cordials. The opium in theriac would have dulled pain and created a sense of calm, which likely explains its enduring reputation, but none of these concoctions could fight the underlying bacterial infection.
Aromatic Protection and “Purifying” the Air
Because miasma theory blamed foul air for the plague, strong smells became a front-line defense. Wealthy citizens carried pomanders, small perforated containers filled with aromatic herbs and spices. Plague doctors, whose iconic beaked masks appeared by the 17th century, packed the long beak-shaped nose piece with dried roses, carnations, lavender, peppermint, camphor, juniper berries, cloves, myrrh, and vinegar-soaked sponges. The idea was that breathing through these fragrant filters would block the corrupted air from entering the body.
A widely circulated folk recipe known as “Four Thieves Vinegar” followed the same logic. The legend held that four thieves robbed plague victims’ homes without falling ill, protected by a vinegar infusion of lavender, sage, mint, and rosemary or thyme. Whether or not the story was true, vinegar-and-herb preparations became popular prophylactics across Europe. At the city level, authorities ordered bonfires of juniper, sulfur, and aromatic wood in public squares, and mandated the removal of garbage and waste from streets. The sanitation measures, though motivated by the wrong theory, likely did reduce contact with rats and fleas.
Folk Remedies and the Live Chicken Treatment
Among the stranger treatments was a procedure sometimes called the Vicary Method, which involved placing a live chicken directly on a patient’s bubo. The instructions were specific: pluck the feathers from around the chicken’s rear end, press that bare skin against the swollen lymph node, and hold the bird in place until it dies. Then replace it with a fresh chicken and repeat. The rationale, developed by German physicians in the 15th century, was that the chicken breathed through its backside and would therefore inhale the poison from the bubo into its own body. Some practitioners went so far as to hold the chicken’s beak shut during treatment to force it to “breathe from below.” Others sprinkled salt on top of the chicken or emphasized the bird’s body heat as the active healing force.
This treatment had ancient pedigree. The Persian physician Avicenna had recommended placing a cut chicken on poisonous bites and stings centuries earlier. By the 16th century, variations of the live chicken cure appeared in medical texts across Europe. It did nothing to help plague patients, but its persistence across centuries shows how desperate people were for any treatment that seemed to offer a physical mechanism of action.
Quarantine: The Treatment That Actually Helped
The single most effective response to the plague came not from medicine but from public health policy. In 1377, the Republic of Ragusa (modern-day Dubrovnik, Croatia) became the first city in history to establish a mandatory quarantine, requiring people arriving from plague-affected areas to isolate for 30 days on three uninhabited islands. The practice evolved, and the word “quarantine” itself comes from the Italian “quarantina,” meaning 40 days, the period that eventually became standard.
Venice took the concept further. In 1423, the Venetian Senate established the world’s first purpose-built isolation hospital on the island of Santa Maria di Nazareth. The facility’s name gradually shifted from Nazaretum to Lazaretum to “Lazaretto,” a term that spread worldwide to describe plague hospitals. These lazarettos were staffed by state personnel and represented a remarkable shift: at a time when care for the sick was almost entirely managed by the church, Venice created a secular public health institution funded by the government.
The Italian quarantine system that emerged had five core elements: controlling movement between healthy and infected areas, ensuring proper burial of the dead and burning of their belongings, isolating the sick from the healthy, providing food and water to quarantined people so desperation wouldn’t drive them back into the population, and offering economic support to those who lost their livelihoods due to trade disruptions. These measures, born from the simple observation that disease spread between people, were centuries ahead of any available medical treatment.
Religious Responses and the Flagellants
For many people, especially during the Black Death of 1347 to 1351, the plague was above all a spiritual crisis. The Bible provided ample precedent for God punishing humanity with pestilence, and the logical response was to seek forgiveness. Churches organized processions, special masses, and days of fasting and prayer.
The most extreme expression of this belief was the flagellant movement. Groups like the Brothers of the Cross traveled from town to town, publicly whipping themselves with leather straps and chains in an attempt to atone for humanity’s sins and avert God’s wrath. The movement surged during the mid-14th century as the Black Death swept across Europe. Flagellants believed their suffering could substitute for the divine punishment being visited on the population. Church authorities eventually condemned the movement as heretical, but for a period it attracted thousands of participants, and towns welcomed flagellant processions as a form of communal spiritual medicine.
How Islamic and European Approaches Differed
Both Christian and Islamic physicians shared the corrupted-air theory and the humoral framework, but their treatments diverged in notable ways. European physicians, increasingly trained at universities that were separating medicine from theology, recorded a wider variety of pharmaceutical remedies. Islamic medical practice during this period was moving in the opposite direction, with religious officials in the Mamluk Caliphate pushing to incorporate more traditional and religious treatments into medicine.
The differences showed up in specific procedures. When performing bloodletting, Islamic physicians like Ibn Khatima instructed that if the bubo was in the armpit, blood should be drawn from the opposite side of the body, but if it was in the neck or groin, from the same side. European physicians followed the opposite rule, fearing that drawing blood from the wrong side would pull corrupted humors across the heart. Islamic physicians also favored bleeding patients to the point of faintness, while European doctors preferred smaller, more cautious draws. One belief unique to European culture, with no parallel in Islamic sources, was the idea that specific planetary alignments had triggered the plague. Another dark distinction: in parts of Germany and Spain, lower-class populations blamed Jewish communities for supposedly poisoning wells, a paranoia that led to massacres. No evidence of this scapegoating existed in regions where Muslims and Jews lived alongside each other.