Fumigation and incense in the battle against medieval plague

During outbreaks of the Black Death, the advice from most doctors and surgeons was very straightforward. “Flie away speedily”, was what Thomas Thayre recommended in 1603. The physician Andrew Boorde recorded in 1547 that, in order to save themselves, “people do flee from the contagious & infectious ayre”. Of course, when the plague arrived, it was not always practical for people to vacate the area until the disease had subsided. Some could simply not afford to, while others, such as the doctors, had duties to perform that could not be neglected.

Medieval medicine has a number of recommendations for how to avoid the plague if you had to remain in an infected area. One such method was called “rectification of the air”. “Rectification” or “correction” relied on the idea that since the disease was caused by a corruption or disturbance in the atmosphere, then perhaps the infection could be avoided by changing the air in a targeted way. The most popular way of doing this was through fumigation – the burning of herbs, woods, and other substances to produce smoke or fumes.

Fumigation had a long history in medicine. Ancient Assyrian medical texts suggested using the smoke of herbs, tree sap, and insects to treat eye complaints and gynaecological problems. In Ancient Greek medicine, fumigations were popular treatments for breathing problems, where the patient would be advised to sit over a fire made of aloe wood and incense and inhale the smoke.

Medieval medicine continued this practice, but it also developed a new method of fumigation. Instead of aiming the smoke at a particular part of the patient, the fumes were instead designed to treat an imbalance or disturbance in the atmosphere. Just as the smoke of certain medical ingredients could cure an individual patient, it was logical for them that applying smoke to the air in a room, house, or street would bring about the same therapeutic effects.

Often these fumigations were made with very simple ingredients. The copy of Thomas Moulton’s popular medical text The Myrrour or Glasse of Helth (1545) (classmark: CP 16 / MOU) held by the RCS England Library contains just such a fumigation recipe:

Use fyer in thy chamber all the times of the day & of the night of these things as fier: of Jenoper, & if thou maye not get this Jenoper make the fyer of clene dry Aschewod, and use to cast in the fier always, frankensens, Storax Calamite, Lapdanum, and the fumosyties of these and the smoke, yf the ayre be corrupt hit will expel it.

Here Moulton is recommending a wide range of substances that could be used in a fire. Juniper wood was a very popular ingredient for medical fumigation right through the medieval and early modern periods. But if this wasn’t available, then readers could swap it out for the wood of the ash tree. He also recommends rarer and more costly items. Frankincense, Calamite storax, and Lapdanum are all resins from trees which grow in Africa and the Middle East and remain popular ingredients in incense and perfume.

Thomas Cogan was aware that these sorts of ingredients were probably out of reach for most readers. In his Haven of Health (1605) (classmark: CP 8 / COG), as well as the standard ingredients such as Frankincense, he writes:

if you will not be at cost, [make fires] with dryed Rosemaire, or as pore folkes use to doe in grete townes, with rushes or broome, or heye

These were all very straightforward ways of “rectifying” the air, as people only needed to throw the ingredients in the open fire that was the centre of most household activities in this period. However, there was often a concern that most of the useful smoke would escape through the chimney. The solution to this was to use a different heat source.

Ordinary rosemary, Theatrum Botanicum (1640).

Again, Thomas Moulton recommends that “in an erthen pan ful of Charcole fyer caste this powder made of these things, of Lorell levys, dried, Rosemary dryed and frankensens of each of them alike much and caste halfe a sponefull of thys powder in the fyer”. This “erthen pan” was a popular early modern kitchen utensil known as a “chafing dish”. A chafing dish could contain a few hot coals from the fire, over which a dish could be placed in order to cook food or keep it warm. It was a popular choice for fumigation for a number of reasons. Firstly, it was readily available in most households, meaning that no specialised equipment was needed. Although many wealthy households might possess specialised dishes and pans for fumigations, these were beyond the budget of most households. Secondly, it was portable, which meant that even rooms without a fireplace would be fumigated.

From George Thomson’s Loimotomia: or The Pest Anatomized (1666) (classmark: CQ 16 / THO), showing the dissection of a plague victim and a chafing dish being used for fumigating the air in the foreground. Licence: Public Domain Mark Credit: George Thomson. Line engraving, 1666. Wellcome Collection. Source: Wellcome Collection.

This method of fumigation even received government support in 1578. The Privy Council of Queen Elizabeth I published a set of recommendations for how to survive outbreaks of the plague, known as “Orders thought meet by Her Majesty”, which were reissued several times. They recommend to:

make fires rather in Pannes, to remove about the Chamber, than in Chimneis, [which] shall better correct the aire of the houses.

They also provided a standardised recipe of “Rosemarie dried, or Juniper, Bay Leaues, or Frankincense cast the same on a Chafindishe”.

But how were these fumigations and different combinations of ingredients meant to work to “rectify” the air? Plague was believed to originate when there was a large amount of rotten material releasing dangerous fumes into the air. This rot was made worse when the air was very hot and humid. Thus, a natural solution was to try and dry out the air. Making a fire on its own would help to do this, but this could be made more effective by burning substances considered to have a “dry” complexion, such as storax, cinnamon, and juniper wood. In the summertime, ingredients were also recommended which were also considered cool. These substances were not cool to the touch, especially not when burned on a fire, but were considered to have a “cool” complexion and, when taken as medicines, would cool down the body. Such ingredients included roses, camphor (another type of plant resin), and violets. Combining these with “dry” ingredients would create a fumigation that could both cool down and dry out the air, and slow down the rot of organic materials, which was believed to bring about the plague.

Juniper, Theatrum Botanicum (1640).

English physicians also drew from practices in Europe. In a 1556 book called Liber de febre pestilentiali (“Book on Pestilential Fever”) (classmark: CP 8 / MAS), the Italian physician Niccolo Massa provides a number of complex fumigation recipes, in which the ingredients are powdered and made into small tablets or pastilles. He recommends using a mixture of rosewater and tragacanth, a naturally occurring gum, as a binding agent. This meant that fumigation compounds could be stored and transported more easily, especially by physicians and surgeons visiting the homes of the sick. Indeed, these sorts of fumigation were believed to provide protection while out and about, as well as in the home. This image from the Fasciculus medicinae attributed to Johannes de Ketham and printed in 1495, shows a doctor visiting a plague patient at home. For the protection of himself and his attendants, the doctor is accompanied by two men holding tall fumigation torches, which would allow him to be shrouded in a protective atmosphere of smoke. For added protection, he holds a sponge, probably soaked in a purifying substance such as rosewater or vinegar, to his nose while taking the patients pulse.

Plague patient from Johannes de Ketham’s Fasciculus medicinae (1495).

Fumigation was a lot more complex than simply covering up “bad smells”, which is often how the practice has been interpreted. Texts from this period held by the RCS England Library show the wide range of methods of fumigation practised in the medieval and early modern periods, as well as showing that it was motivated by a developed understanding of how the plague developed and spread through the air. This early form of “air conditioning” continued to be popular well into the 18^th century, but had its roots in much older medical traditions.

Thomas Banbury, Henry Lumley Collections Engagement Grant holder, 2025-2026.