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Discoveries and treatments

Paracelsus is frequently credited with reintroducing opium to Western Europe during the German Renaissance. He extolled the benefits of opium, and of a pill he called laudanum, which has frequently been asserted by others to have been an opium tincture. Paracelsus did not leave a complete recipe, and the known ingredients differ considerably from 17th-century laudanum.

Paracelsus invented, or at least named a sort of liniment, opodeldoc, a mixture of soap in alcohol, to which camphor and sometimes a number of herbal essences, most notably wormwood, were added. Paracelsus's recipe forms the basis for most later versions of liniment.

His work Die große Wundarzney is a forerunner of antisepsis. This specific empirical knowledge originated from his personal experiences as an army physician in the Venetian wars. Paracelsus demanded that the application of cow dung, feathers and other noxious concoctions to wounds be surrendered in favour of keeping the wounds clean, stating, "If you prevent infection, Nature will heal the wound all by herself." During his time as a military surgeon, Paracelsus was exposed to the crudity of medical knowledge at the time, when doctors believed that infection was a natural part of the healing process. He advocated for cleanliness and protection of wounds, as well as the regulation of diet. Popular ideas of the time opposed these theories and suggested sewing or plastering wounds. Historians of syphilitic disease credit Paracelsus with the recognition of the inherited character of syphilis. In his first medical publication, a short pamphlet on syphilis treatment that was also the most comprehensive clinical description the period ever produced, he wrote a clinical description of syphilis in which he maintained that it could be treated by carefully measured doses of mercury. Similarly, he was the first to discover that the disease could only be contracted by contact.

Hippocrates put forward the theory that illness was caused by an imbalance of the four humours: blood, phlegm, black bile and yellow bile. These ideas were further developed by Galen into an extremely influential and highly persistent set of medical beliefs that were to last until the mid-1850s. Contrarily, Paracelsus believed in three humours: salt (representing stability), sulphur (representing combustibility), and mercury (representing liquidity); he defined disease as a separation of one humour from the other two. He believed that body organs functioned alchemically, that is, they separated pure from impure. The dominant medical treatments in Paracelsus's time were specific diets to help in the "cleansing of the putrefied juices" combined with purging and bloodletting to restore the balance of the four humours. Paracelsus supplemented and challenged this view with his beliefs that illness was the result of the body being attacked by outside agents. He objected to excessive bloodletting, saying that the process disturbed the harmony of the system, and that blood could not be purified by lessening its quantity. Paracelsus believed that fasting helped enable the body to heal itself. 'Fasting is the greatest remedy, the physician within.'

Paracelsus gave birth to clinical diagnosis and the administration of highly specific medicines. This was uncommon for a period heavily exposed to cure-all remedies. The germ theory was anticipated by him as he proposed that diseases were entities in themselves, rather than states of being. Paracelsus prescribed black hellebore to alleviate certain forms of arteriosclerosis. Lastly, he recommended the use of iron for "poor blood" and is credited with the creation of the terms "chemistry," "gas," and "alcohol".

During Paracelsus's lifetime and after his death, he was often celebrated as a wonder healer and investigator of those folk medicines that were rejected by the fathers of medicine (e.g. Galen, Avicenna). It was believed that he had success with his own remedies curing the plague, according to those that revered him. Since effective medicines for serious infectious diseases weren't invented before the 19th century, Paracelsus came up with many prescriptions and concoctions on his own. For infectious diseases with fever, it was common to prescribe diaphoretics and tonics that at least gave temporary relief. Also many of his remedies contained the famed " theriac ", a preparation derived from oriental medicine sometimes containing opium. The following prescription by Paracelsus was dedicated to the village of Sterzing:

Also sol das trank gemacht werden, dadurch die pestilenz im schweiss ausgetrieben wird: (So the potion should be made, whereby the pestilence is expelled in sweat:) eines guten gebranten weins...ein moß, (Medicinal brandy) eines guten tiriaks zwölf lot, (Theriac) myrrhen vier lot, (Myrrh) wurzen von roßhuf sechs lot, (Tussilago sp.) sperma ceti, terrae sigillatae ietlichs ein lot, (Medicinal earth) schwalbenwurz zwei lot, (Vincetoxicum sp.) diptan, bibernel, baldrianwurzel ietlichs ein lot (Dictamnus albus, Valerian, Pimpinella) gaffer ein quint. (Camphor) Dise ding alle durch einander gemischet, in eine sauberes glas wol gemacht, auf acht tag in der sonne stehen lassen, nachfolgents dem kranken ein halben löffel eingeben... (Mix all these things together, put them into a clean glass, let them stand in the sun for eight days, then give the sick person half a spoonful...)

One of his most overlooked achievements was the systematic study of minerals and the curative powers of alpine mineral springs. His countless wanderings also brought him deep into many areas of the Alps, where such therapies were already practised on a less common scale than today. Paracelsus's major work On the Miners' Sickness and Other Diseases of Miners (German: Von der Bergaucht und anderen Bergkrankheiten) presented his observation of diseases of miners and the effects of various minerals and metals in the human organism.