I'm allergic to augmentin. It's not a really common thing to have to deal with in nature, but it pretty much ensures that I won't be prancing around eating strange mushrooms I find in the woods after it rains.
Actually, I once asked a licensed paramedic whether or not being allergic to augmentin would do anything to me out in nature, and his reply actually was, quote, "As long as you don't go around eating weird mushrooms, you should be fine." The look on his face was quite serious, too, so I took his advice to heart.