5,000 B.C. -1500 A.D.:The first inhalers

Like the discovery of fire, the first inhaler was probably the product of an accident, or mere coincidental reaction of thinking man.

After playing with certain herbs, they may have been tossed into the fire, and a brief ease of temperament may have ensued by those who inhaled the fumes.  Upon further study it must have been learned that the herb in question, perhaps opium, could be used for recreation -- a gift from the gods, perhaps.

Experimentation must have ensued with other drugs, perhaps by a medicine man.  It was ultimately learned that inhaling the fumes of dried and crushed herbs such as black henbane, strammonium, and belladonna resulted in relaxation of the mind.  Then one day an asthmatic, coincidentally perhaps, noticed his breathing was eased by such an inhalation.

To better direct the fumes, some unknown tinkerer tossed a brick into the fire, took it out while it was piping hot, and tossed the herbs onto this, crouched down upon his knees, placed his nose up close to the fumes, and inhaled.  This was a technique mentioned by ancient Egyptian scribes.

Such technology must have made it's way to Greece, and physicians fine tuned this discovery so the medicine was placed in a simple pot with a hole in the lid.  A hollow reed was inserted into the hole, and the patient placed his lips to the reed and inhaled the fumes this way.  (1)  The "herbs and resins were boiled with vinegar and oil which were drawn into the lungs" through the tube.  (2)

Such a device was mentioned by the Hippocratic writers, and perhaps even Hippocrates himself.
Various medicines would have been experimented with, and trialed for certain symptoms.  You may have tried it for your asthma, although that's not necessarily what Hippocrates himself would have prescribed.

From Hippocrates onward physicians and philosophers and other interested persons obtained the writings of Hippocrates, and they copied him.  Each successive expert on such devices shared this wisdom through their own writings, often plagiarizing previous authors.  The works of most of these authors have disappeared in time, although shared vaguely through works that still remain.

Experimentation and observation educated men that certain herbs helped certain symptoms quicker when inhaled.  It was learned that patients complaining of certain symptoms showed certain signs.  For example, the child complaining of a stuffy, runny nose and breathing trouble had a red and inflamed nasal passage and throat.  These symptoms were eased by directly inhaling certain herbal combinations.

First by word of mouth, and then by texts, this knowledge traveled through time.  Medicine men, and later physicians, learned that the vapours of certain herbs helped patients experimenting symptoms of breathing difficulty and cough were associated with signs such as red, inflamed nasal passages.  Terms such as dyspnea, cough, catarrh, and coryza are recognized over time, treated with various inhaled herbal preparations.

Found in Valencia circa 800B.C.-1200A.D. (6)

By studying the works handed to them, Greek and Roman physicians experimented on their own and came up with adaptations and theories.  In Ancient India various herbs were stuffed into crude pipes and inhaled. (2)

In Rome Galen wrote about such inhalations by means of devices similar to that described by Hippocrates.  So to did Actius (500-600? A.D.).  And so to did Arabic authors such as Rhases, Aegineta, Avicenna and Haly Abbas.  (3, page 7)  Around 1190 A.D. Mamonides recommended the primitive method of tossing herbs into the fire and inhaling.  (1,2)

The medicinal, or recreational, component varied through time.  In ancient Greece and India it may have been Black Henbane, Strammonium,  Belladonna or Indian Hemp, all of which would have provided some hallucinogenic qualities necessary to ease the mind of the sufferer, and to generate mild relief from breathing difficulties.

One of earliest discovered medicines was opium, and this may also have been inhaled and prescribed by various medicine men in the primitive world and physicians in the ancient world. Opium inhalation was prescribed in ancient China through metal inhalers or incense.  (2)

Arica Inhaler (Northern Chile, Southern Peru, 1500 A.D.)(7)

Other substances, wither herbal or solutions, were experimented on at various times.  Haly Abbas, for example, recommended inhaling vapors of vinegar, camphor, arsenic and other substances.  Avicenna recommended inhalation of pine fruit.  These remedies may also have been recommended for diseases such as asthma, phthisis (tuberculosis of the lung), bronchitis, emphysema and other diseases of the airway (3, page 7)

Paulus Aegineta (930-1037 A.D.) recommended arsenic in "fumigation with resin in chronic cough, when its steam is inhaled by means of a syphon." (5, page 324-5)

Such technology made its way as far as central America by 1500 A.D. as an inhaler of sorts was used in Southern Peru.  It consisted of a small, decorated plate-like device that held a combination of tobacco-like substances that were inhaled through a small, hollowed out wooden mouthpiece.  It may not have been used for medicinal purposes, although it was an inhalation device.  (4)

References:

1. Anderson, Paula J, "History of Aerosol Therapy: Liquid Nebulization to MDIs to DPIs," Respiratory Care, 2005, September, volume 50, number 9, pages 1139-1150 
2. Sanders, Mark, "Inhalation Therapy: An Historical Review," Primary Care Respiratory Journal,  2007, volume 16, issue 2, pages 71-81
3. Scutter, John M, "On the use of medicated inhalations in the treatment of diseases of the respiratory organs," 1867, Cincinnati, Moor, Wilstach, and Baldwin
4. Sanders, Mark, "Arica Inhaler," Inhalatorium.com, page 120,  http://www.inhalatorium.com/page120.html.  Also see  Anderson, Paula J, "History of Aerosol Therapy: Liquid Nebulization to MDIs to DPIs," Respiratory Care, 2005, September, volume 50, number 9, page 1140.  Picture compliments of Inhalatorium.com.  
5. Aegineta, Paulus, translated by Adams, Francis, "The Medical Works of Paulus Aegineta, The Greek Physician, 1834, vo 1, page 325
6. Sanders, Mark, "Ancient Pipes," page 57,  http://www.inhalatorium.com/page72.html, accessed 9/21/12
7. Sanders, Mark, "Arica Inhaler," page 120,  http://www.inhalatorium.com/page120.html, accessed 9/21/12