The Byzantine Empire, with its capital in Constantinople (now Istanbul), then a mainly Greek-speaking region, constituted a natural crossroads between East and West for more than a millennium (AD 324–1453). Its history is an indispensable part of the medieval period in both Europe and the Middle East. In the field of medicine, for example, we can attest to widespread interactions with the Islamic tradition.
The most dynamic part of Byzantine therapeutics was pharmacology. We are privileged to have several surviving pharmacological manuals, especially dating from the later period, i.e. from the twelfth to the fifteenth centuries, which provide us with a unique testimony to Byzantine composite drugs. Here I have selected the example of sugar-based potions, as it offers an excellent case-study that helps us to better understand the way Byzantine recipes were developed through a process of both practical experimentation and influence from outside.
Before the introduction of sugar, people relied on honey to make medical potions sweet. Greek and early Byzantine medical authors referred to honey-based drugs such as oinomeli (a mixture of honey with wine), hydromeli (a mixture of honey with water) or oxymeli (a mixture of honey with vinegar). For example, Paul of Aegina (fl. first half of the seventh century) recommends the following recipe for those suffering from calculi:
One ounce each of saxifrage, betony, dog’s-tooth grass, maidenhair fern, spikenard, carpesium, hazelwort, and eryngo; one half ounce each of Macedonian parsley and seed of rue; two ounces each of green fennel, iris, baked squill, and periwinkle; three ounces of bark of the root of capper; two ounces of water-parsnip; and two sextarii each of water, vinegar, and honey.
Meanwhile, the cultivation of sugarcane gradually spread throughout the Islamic East from the seventh/eighth century onwards. Sugar was used as a simple drug, for stomach ailments and the relief of pain in, for example, the chest and kidneys. However, it also became popular as an excipient in liquid pharmaceutical dosage forms, used as a sweetener and preservative, initially supplementing and gradually replacing the use of honey for pharmacological purposes in the Islamic world. Sugar is of higher purity than honey, thus a smaller quantity has a stronger preservative action; it is also less susceptible to changes of temperature and ensures greater homogeneity into the final product. Among the most commonly used potions in Islamic medicine are the so-called julep (julāb) and syrup (sharāb), both of which consisted of sugar and one or more kinds of fruit juices or extracts of flowers.
By the eleventh century sugarcane cultivation was thriving in Syria and Palestine, eventually reaching the large Mediterranean islands of Cyprus and Sicily. Western merchants, such as the Genoese and the Venetians, played an important role in the distribution of this commodity throughout the Mediterranean, including Byzantium. For example, sugar is mentioned among the main supplies for the newly established Byzantine hospital (xenon) of the Pantokrator Monastery in Constantinople in the early twelfth century, but it was not until the late thirteenth century that sugar became widely available in the Byzantine world.
At the same time, we can observe the transfer of medical knowledge to Byzantium through translations of Arabic and Persian works into Greek. The earliest text of this kind, which preserves a large number of references relating to the various kinds of sugar-based potions, is the Greek translation of Ibn-Jazzār’s (fl. tenth century) Ephodia tou Apodēmountos (Zād al-musāfir wa qūṭ al-ḥāḍir/Provisions for the Traveller and Nourishment for the Sedentary), which must have been translated in the late eleventh/early twelfth century by scholars working in Southern Italy. By the early fourteenth century recipes for sugar-based potions had become very common in Byzantine manuals. The Constantinopolitan medical author and practising physician John Zacharias Aktouarios (ca. 1275–ca. 1330) provides an extensive list consisting of about thirty recipes, and he often explicitly acknowledges that he was introducing a new recipe. For example, he gives the following recipe for a julep for heart palpitations:
One hexagion of the three sandalwoods; three hexagia of violet; two hexagia of basil seed; two hexagia of rose; five hexagia each of bugloss and ox-eye flowers; two hexagia of aloeswood; one hexagion of ambergris; two hexagia of saffron; three hexagia each of dried flower-buds from the clove-tree and nutmeg; one hexagion each of cinnamon, anise, caraway, and fennel seed; five grains of musk; one hexagion of poppy seed; three ounces of the juice of sweet apples; one ounce of rosewater; five ounces of distilled endive water; one ounce each of the roots of fennel, wild celery, and chicory; three hexagia each of marjoram, chamomile, and wormwood; and three ounces of sugar.
In this recipe, in addition to sugar, we can also see ingredients from Asia and the Far East, such as musk, amber, and sandalwood, which became common in European pharmacology, especially during the thirteenth and fourteenth centuries after the Mongols’ conquests in Eurasia that led to the Pax Mongolica and the resulting improvements in trading conditions. To sum up, the fact that Byzantine physicians were aware of the usefulness and effectiveness of these sugar-based potions and made extensive use of them is at odds with the established view that Byzantine society was not very open to outside influence. Nowadays sugar is omnipresent and often replaced by sugar substitutes for the sake of diabetics and the diet-conscious; but once it was a novelty and highly desirable!
 One ounce is equal to 27.288 g.
 One sextarius is equal to 54.58 g.
 One hexagion is equal to 5.166 g.
Petros Bouras-Vallianatos studied pharmacy, ancient and Byzantine history, before completing his PhD on the late Byzantine medical author John Zacharias Aktouarios; a revised version of his doctoral thesis is to be published soon. He is Wellcome Trust Research Fellow in Medical Humanities in the Department of History at King’s College London, where he is working on a three-year project entitled ‘Experiment and Exchange: Byzantine Pharmacology between East and West (ca. 1150-ca.1450)’. He has published several articles on Byzantine and early Renaissance medicine and pharmacology, the reception of the classical medical tradition in the Middle Ages, and palaeography, including the first descriptive catalogue of the Greek manuscripts at the Wellcome Library in London. He is also co-editing the Brill’s Companion to the Reception of Galen.