1483: The King uses his allergies to kill Lord Hastings

Figure 3 -- King Richard III (1452-1485)

Legend has it that King Richard III (1452-1485) knew he had an allergy to strawberries, and in 1483 he used this wisdom to kill his arch enemy, Lord William Hastings. (2, page 4)

The King purposely ate some strawberries and blamed his allergic reaction on a curse from Lord Hastings. For his punishment Lord Hastings was beheaded, and his head was served on a platter. (2, page 4)

The king was able to get away with this because nobody knew about allergies other than those who suffered from them.  Other than the king, most allergy sufferers were hard working men and women who had little time to let minor suffering slow them down.

And even when they did report their symptoms to physicians, they were generally brushed off as something minor, like a cold. Physicians had better things to worry about, such as deadly plagues.

References:

1. Cantani, "Pediatric Allergy, Asthma and Immunology," 2000, New York, page 724
2. Ehrlich, Paul M., Elizabeth Shimer Bowers, "Living with Allergies," 2008