Science

How a grapefruit burned me ... literally!

A personal account of what happens when grapefruit juice meets skin under a hot sun.

Ahhhh, the lazy days of summer. Time to relax and spend time at the cottage with friends or, if you're me, spend time at the cottages of friends.

A closeup of the author's hand, two weeks after she accidentally dribbled grapefruit juice on it and exposed it to the sun. ((Ramya Jegatheesan/CBC))
And so it was that I spent the Canada Day weekend at my friends' place in Haliburton, Ont., a prime cottage area about 200 kilometres north of Toronto.

It was exactly as a perfect cottage weekend should be: hot, sunny and long.

But then, on Sunday morning, a most bizarre — and ultimately fateful — sequence of events unfolded: I picked a juicy piece of grapefruit out of a fruit salad with my fingers, bit into it, dribbled grapefruit juice down the back of my right hand and went out into the sun.

Hours later, the back of my hand was burned so badly that it eventually blistered, peeled and blistered again.

Phytophotodermatitis:

Medical definition: "a non-immunologic, phototoxic reaction resulting from the activation of furocoumarins (photosensitizing botanical substances present in limes, hogweed and other plants) by long-wavelength ultraviolet radiation (UVA)."

What that means: skin exposed to a certain substance in some plants becomes hypersensitive to UV rays and will burn easily

Symptoms: blisters or swellings may occur minutes to hours after exposure to the plant and light, but more usually erupt about 24 hours after exposure, peaking at 48 to 72 hours. Hyper-pigmentation, or unusual darkening of the skin, is also common.

Culprits: sunshine plus photosensitizing compounds in some plants, including members of the Umbellifrae (celery, hogweed), Rutaceae (limes, grapefruits), Moraceae (figs) and Leguminosa (beans) families.

Who's at risk: everybody. The condition is not related to the immune system and "can occur in any person who has been exposed to adequate amounts of a photosensitizing chemical and [ultraviolet radiation]," according to the Electronic Textbook of Dermatology.

Source: The New Zealand Dermatological Society

At first, it just seemed as if I'd forgotten to put sunscreen on the back of my hand and left it exposed for too long. But I had put on sunscreen, and the rest of me, also under cover of SPF 30, was just fine. No other burns.

At home that night, my hand swelled, throbbed and began to blister. I poked at it, coated it with Neosporin, swallowed some ibuprofen and went to bed.

By the next morning, the back of my thumb was blistered and the rest of the affected area — a splotch roughly the size of a kiwi slice — was a dark red-brown colour. I also noticed similar patches on the bottom parts of my middle and fourth fingers.

I applied Neosporin assiduously and was glad when, five days later, my hand seemed to be healing.

I celebrated with a two-hour bike ride on Saturday evening. Big mistake. Despite a thick layer of SPF 30, the entire splotch blistered and was so full of fluid that I could feel it sloshing around when I brushed my teeth. And it hurt. A lot.

Now, it's pretty hard to gross me out. I used to check out the pictures of leprous body parts in my parents' anatomy books when I was a kid, for example, and have never been queasy about scabs or scrapes.

But a sloshing blistery hand is pretty gross, and worse yet, looks gross, prompting gasps and "Oh my gosh! What happened to you?!" from friends, family members and even some strangers.

And so, after much prompting, I went to the doctor.

The diagnosis? Phytophotodermatitis, a hypersensitivity of the skin to ultraviolet light caused by the photosensitizing properties of some plants — including grapefruit. It's also linked to that pesky hogweed we've been reading so much about lately.

Unlike a typical sunburn, it's not something you can just get rid of, I'm told. I've been referred to a dermatologist for further treatment including, possibly, a steroid cream to treat it or even laser surgery to remove the hypersensitive splotch.

No appointment's been made yet, but I'm hopeful it will happen soon. For now, I have to keep my hand covered whenever I'm in the sun.

So, if you see a woman wandering around with a big patch of gauze taped to her hand this weekend, that could be me. If she's eating grapefruit, too, though, then it probably isn't.