A lot, but here's the major ones:

Iodine
Erythromycin
Biaxin
Seafood
Shellfish
Bee/Wasp/Hornet stings
**All the above could potentially be life threatening to me

Misc. allergies:

Cats/Dogs and their dander
Golden Rod/Grass
Dust
Cologne, Perfume (can trigger a sudden headache/migraine)

I have had side effects or intolerance with:

Tegretol (Carbamazepine)
Amitriptyline
Neurontin
Nortriptyline

I have difficulty (discomfort) with:
Oranges - Mouth ulcers (canker sores)
Tomatoes and Strawberries - Mouth discomfort (feels like I've been cut with tiny shards of glass)

I'm sure there's a bunch I'm forgetting. Seems acidic foods aren't too kind to my body, but not deathly allergic to, thankfully.

(I know we were to discuss medications, but I figured I'd add others that affect me)