I learned the hard way this week that common English Ivy (Hedera helix) can cause severe allergic reactions to a small and unfortunate percentage of the population (including myself). Has anyone else experienced this?

I've always been unusually sensitive to poison ivy (toxicodendron radicans), and I have learned out of self preservation to spot PI from yards away. Earlier this week I was cutting English ivy http://www.nps.gov/plants/alien/fact/hehe1.htm from around a sycamore I was eyeing for a future climb. I know that it was NOT PI since it had variegated evergreen leaves just like in the images linked above. That was on Tuesday afternoon. About 24 hours later my eyes started to swell. Originally I thought I was coming down with pink eye, except that there was no discharge from my eyes and my cornea wasn't red. The swelling (and itching) increased gradually all day Thursday. By the wee hours of Friday morning one eye had swollen shut and I decided I better head to urgent care first thing in the morning.

The doctor prescribed a seven day regimen of the immunosuppresant drug prednisone to decrease the swelling. The prednisone helped significantly and by Saturday afternoon I was feeling pretty good with only minimal swelling. At this point I still wasn't convinced that pulling down the English ivy on Tuesday had lead to the apparent allergic reaction -- that would have been quite a delayed response. So... what better way to enjoy the afternoon sunshine than to head to a large oak tree at the edge of my neighborhood that I had spotted a while ago, but not yet climbed?!

My son and I made our way to the wild tree and got ready to set our lines. The tree is a 12' CBH beauty, the largest around, with plenty of nearly horizontal limbs for limbwalking and hanging out. Pictures here: http://www.facebook.com/media/set/?set=a.2735242986391.2119064.1416815241&type=3 I couldn't help but notice the old, dead vines still clinging to the trunk, though, as I tried to set our lines. I went up first to clear away a couple of widow makers and I started to pull some of the dead brittle vines out of the tree as well. I'm sure the vines were English ivy remnants and not PI because the main vine was ~5 inches in diameter at the base of the tree and I have never known PI to get so large as a climbing vine.

I thought rationally about the possible ramifications before pulling out the vines. I knew there was a chance that even dead vines could cause a reaction if I am indeed allergic to English ivy, but the scientist in me saw an opportunity for a controlled experiment and after all, I surmised, I still had 4 days of prednisone left.

Well you guessed it, I woke up this morning with newly swollen eyes and a nice, itchy rash on my neck where chips and splinters from the vine had fallen between my collar and skin. I'll spare you the photos of my puffy face in case I ever run for president.

It's interesting to me that my hands and arms never reacted to the English ivy. On Tuesday when I was pulling the live vines off the sycamore I wasn't even wearing gloves and both days I had a short sleeve shirt on. My guess is that little flecks of vine in both cases fell onto my eyes and then irritated the thin inner lining (conjunctiva) of my eye lids. Here's a link talking about the allergen found in English ivy, falcarinol http://dermnetnz.org/dermatitis/plants/ivy.html.

I guess the sycamore, the wild oak, and any other ivy-infested trees will be off limits for me from now on. Bummer! ...but at least I know for sure now.

Definitely scientific of you - unethical to experiment on others, but experimenting on yourself is scientifically acceptable

I'd be wary about other ivies you might be allergic too that you don't know about. Some allergic reactions get more severe with repeated exposure. The next time the reaction might be quicker. You might already do this (due to the poison ivy), but I'd recommend carrying an epi-pen just in case!

Not a bad idea, Tangle.

Update: It turns out that my arms did break out in rashes the day after I wrote the first post.

update 2 - well it took a full 4 weeks, but I am rash and itch free from the english ivy encounter.