I"m sharing my story here so you don"t make the same mistake I did, and end up with Phytophotodermatitis (PPD). Phytophotodermatitis is also known as plant and sun dermatitis, parsnip burn,and sometimes lime disease (not to be confused with Lyme disease) ormargarita photodermatitis. You get it from exposure to plant sap or juice and sunlight, as outlined below. We"ll cover plants that causephytophotodermatitis and how to treat it.

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This was not parsnip burn from exposure to some “poison parsnip” or giant hogweed. I was working in my garden. Garden parsnips and wild parsnips are the same species, and it turns out they can cause the same problems. Several other plants can cause the problem, too.

I originally wrote this post in 2014, and unfortunately ended up with another smaller case in 2018. I thought I was being careful, but apparently not careful enough.

The pain doesn"t start until days after sap and sun exposure. By then, the damage is done, and all you can do is treat the symptoms.


I"m Going to Stop Growing “Poison Parsnips” Because They"re Too Dangerous

What is Phytophotodermatitis?

Medscape defines Phytophotodermatitis as:

Phytophotodermatitis (PPD) is a cutaneous phototoxic inflammatory eruption resulting from contact with light-sensitizing botanical substances and long-wave ultraviolet (UV-A 320-380 nm) radiation. The eruption usually begins approximately 24 hours after exposure and peaks at 48-72 hours.<1> The phototoxic result may be intensified by wet skin, sweating, and heat.

In other words, your skin erupts with blisters and itchy, burning red areas because you were in contact with plant chemicals (in this case, parsnip and carrot sap) and exposed to sunlight.

You don"t realize you"re in trouble until several days after exposure, by which point, you"re skunked. This is one of the aspects that makes PPD different from most other contact dermatitis. If you"re working with wet plants on a hot summer day, it"s going to be worse. (That"s what happened to me.)

If you visit the Medscape website, they go into a detailed explanation of how the chemicals in the plants that cause the damage (Furocoumarins) are activated in stages under different conditions, and how they actually damage the DNA of the skin.

You cannot “wash off” phytophotodermatitis chemicals with soap and water once they are activated by UV radiation. I did shower after working in the garden, but it didn"t do any good. Washing may help limit additional damage.


Is Phytophotodermatitis contagious?

Nope. Only those directly exposed to the problem plants and conditions experience skin reactions.

The only case that might be an exception is berloque dermatitis, a special type of phytophotodermatitis caused by perfumes. There are older perfumes that used oil of bergamot. (Bergamot is one of the citrus fruits that can trigger PPD.)

If one person applied the problem perfume and was in close contact with another person, they might spread the perfume – and the skin condition. It"s unlikely, but possible.

Which Plants Cause Phytophotodermatitis?

Here"s a kicker – there are wide range of plants that can cause this condition that you might never suspect.

Plants that may cause phytophotodermatitis include (but are not limited to):

Parsnips (Pastinaca sativa)Celery (Apium graveolens)Parsley (Petroselinum crispum)Wild Parsnip (Pastinaca sativa)Limes (Citrus × aurantiifolia)Figs (Ficus carica)Chrysanthemums – Chrysanthemum genus, aster family Common Rue (Ruta graveolens)Russian sage (Perovskia atriplicifolia)

Those who are into botany will notice that the top six plants on the list are all related to each other (they are members of the Apiaceae family). Some of you may have also heard about getting blisters from wild parsnip or poison parsnip, but may not have realized the garden parsnips can also cause burns. Garden parsnip and wild parsnip are both different varieties of the same species – Pastinaca sativa.  The veggies typically cause burns on agricultural workers and grocers, who handle large quantities of plant material.

The Medscape site shows a rather nasty blister that covers about 1/3 of the forearm of a flight attendant who spilled lime juice on her skin. The phytophotodermatitis from limes is also referred to as “margarita dermatitis” because of all those poor folks who have sucked on their limes in the summer sun.

The wild parsnip burns (and those from other wild plants like hogweed or queen Anne"s lace) can be some of the worst, because people do terrible things like running weed whackers with shorts on and get their legs all covered with little bits of parsnip (and sap), like the poor guy featured in the article “Burned by Wild Parsnip” in Wisconsin Natural Resources magazine. The photo below is as example of how large the blisters can get.


I"m Going to Stop Growing “Poison Parsnips” Because They"re Too Dangerous

No. I"m not. I"m not skipping the carrots, parsley or celery, either.

In all my years of gardening, these past couple of decades on my own and helping mom out growing up, I"ve never been burned by garden parsnip before. I did get about an inch long blister from wild parsnip, but none from garden parsnip.

Here"s what I screwed up:

I was workingin the morning, so the plants were covered in dew. More moisture = wet skin.

It was hot, so I was sweating = more wet skin + heat, both triggers for phytophotodermatitis.

The area I was working on was roughly 80 square feet, very thickly planted, mostly with carrots and parsnips. I had thinned and weeded the patch when the plants were younger, but this round of thinning took place when the plants were a couple feet tall.

The only way to reach the roots to pull them out was to stick my arm into lots of foliage. (Lots of exposure.) I gathered up the bundles of plant tops after removing the roots with my bare arms. (More exposure.)

By the time I finished, it was pushing midday, with a bright, beaming blue sky = lots of nice, intense sunlight.

In my 2018 case of phytophotodermatitis, I allowed queen Anne"s lace to grow in the greenhouse as companion plants for the tomatoes. I was trying to thin them out as the greenhouse became more crowded. It was hot, humid and sunny. I must have broken some of the stems, and got the sap on my hands and feet.

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What I Should Have Done:

The simplest thing I could have changed was to wear long sleeves and gloves to cover up my skin. Problem solved.

Alternatively, not handling the broken plants with bare skin, or thinning harder when the plants were small so I didn"t need to stick my arms into a thicket would probably also have done the trick. That said, we have been enjoying the carrots and parsnips I picked.