Perhaps the first known recording of an allergic reaction occurred in ancient Egypt.  About 2640 B.C. King Menses of Egypt was reported to have died after being stung by a wasp. 

Right around this time a Middle Eastern Physician named El-Razi observed redness and swelling of the nasal passages in some of his patients, and what he described in his writings were what we would now consider allergic rhinitis or hay fever.  Yet those terms weren't used until the 19th and 20th centuries.  

Arnoldo Cantani, in his book, "Pediatric Allergy, Asthma and Immunology," (2000, New York, page 724) describes how Caesar Augustus suffered from asthma and seasonal rhinitis (allergies/ hay fever).  Ceasar is also believed to have suffered from asthma. 

Roman Emperor Claudius (10-13 B.C to 54 A.D) is beleived to have suffered from allergy symptoms, and his son Brittanicus (41?-55 A.D.) is believed to have suffered from an allergy to horses. Historical reports have it that when exposed to horses his eyes would swell up and he'd develop a rash.

Brittanicus was heir apparent to the throne.  Yet due to his allergies he was limited in what he could do.  And when his mother died, Claudius remarried to Agrippina the Younger.  She had a son named Nero, and Claudius adapted him.  Nero almost immediately won the favor of the public, and Nero ultimately eclipsed his younger brother and was named Emperor in 54 A.D.

Nero would ultimately become famous for throwing Christians to the Lions.  Yet within only a few months of his reign, he is believed to have poisoned his weaker, older brother Brittanicus to death.  

Dr. Paul M. Ehrlich, in his book, "Living with Allergies" (2009, page 4), explains that it was an Ancient Roman Physycian who was the first to describe allergies.  Ehrlich quotes Lucretius, who lived from 99-55 B.C., as saying, "What is good for some may be fierce poisons for others."

Ehrlich  mentions how legend has it that King Richard III (1452-1485) knew he had an allergy to strawberries and he used this knowledge to kill Lord Hastings.  The King purposely ate some strawberries and blamed his allergic reaction on a curse from Lord Hastings.  Lord Hasting's was beheaded as punishment, and his head was served on a platter.

In 1656 a French doctor named Pierre Borel suspected one of his patients developed a rash when this patient ate eggs.  So one day he attempted to test his theory by placing some egg particles on the patient's skin.  When blisters developed on the patient's skin the physician knew he had made the correct diagnosis.

Physicians around 850 A.D. observed patients with sneezing, nasal stuffiness and runny noses when the roses were blooming.  They referred to this condition as rose fever.

In the 19th century physicians diagnosed hay fever.  The first description of this medical condition were based on the observation that some patients developed nasal congestion, runny nose and sneezes when exposed to hay.  

Ehrlich explains that in 1819 Dr. John Bostock defined hay fever as a disease that caused inflammation of the upper respiratory tract that lead to the annoying symptoms.

Ultimately, however, we would learn that the condition we now refer to as hay fever has nothing to do with hay or hay fever.  Yet the term "hay fever" became a common term of describing a condition we now refer to as seasonal allergies.

According to NationalJewish.org, "In 1902, two French scientists injected dogs with a small amount of extract from the sea anemone (a flower-like marine animal).  Nothing happened.  A week later they repeated the procedure in exactly the same way -- and watched, amazed, as the dogs developed severe reactions.  The dogs had somehow become sensitive to the formerly harmless substance and the researchers discovered allergy."

In 1906 an Austrian pediatrician named Clemons Von Pirquet did studies of his own, and he actually believed that asthma was an allergic condition, and curing this disease was only a matter of finding the right foreign proteins to inject.  History would prove him right in juxtaposing asthma and allergies, yet wrong on the front of this leading to a cure. 

While the term asthma was first used in 800 B.C. by Homer in his Illiad, and later by Hippocrates around 400 B.C., the term allergy wasn't used until 1906.  The first man to use the term was von Pirquet.  Since then scientists have learned quite a bit about allergies.