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) or margarita photodermatitis. You get it from exposure to plant sap or juice and sunlight, as outlined below. We'll cover plants that cause phytophotodermatitis and how to treat it.
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 exposure. By then, the damage is done, and all you can do is treat the symptoms.
What is Phytophotodermatitis?
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. 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 juice (in this case, parsnip and carrot sap) and were out in the sun. You don't realize you're in trouble until several days after exposure, by which point, you're skunked. 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 once they are activated by UV radiation. I did shower after working in the garden, but it didn't do any good.
Is Phytophotodermatitis contagious?
Nope. Only those directly exposed to the problem plants and conditions break out in a rash.
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)
- Carrots (Daucus carota subsp. sativus)
- Celery (Apium graveolens)
- Parsley (Petroselinum crispum)
- Wild Parsnip (Pastinaca sativa)
- Queen Anne's Lace (Wild Carrot) (Daucus carota)
- Giant Hogweed (Heracleum mantegazzianum)
- Limes (Citrus × aurantiifolia)
- Figs (Ficus carica)
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 working in 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.
What I Should Have Done:
The simplest thing I could have changed was to put on an overshirt 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. 🙂 No more wild carrots in the greenhouse. It's simply too easy to get accidental exposure while working around the plants in close quarters.
How do you Treat Phytophotodermatitis
Like a standard burn, you can apply cool compresses to relieve the pain, and try to keep blisters intact as long as possible to protect the tender skin underneath. Over the counter itch cream like those for poison ivy may also help. I hit the pantry and the garden.
On the first couple of blisters, I used fresh plantain and yarrow leaves, mashed and applied as a poultice. As more blisters showed up, I coated the worst blisters with manuka honey to promote healing and fight infection. You can read more about using honey for wound treatment in the post, “Honey as Medicine“. With over 30 blisters on my arms and hands, the honey was a little awkward to try and use on all of them, so I made up some comfrey salve with lavender essential oil.
I coated the burns several times per day with the salve, and at one week after exposure, some of the scabs fell off to expose new skin underneath. The burns on my hands and elbow didn't heal quite as fast. My hands spend way too much time being beat up during canning and gardening season, so I can't keep bandages on them, and the elbow is just awkward to keep bandaged.
Comfrey and Lavender Salve Recipe
Adapted from the Herbal Academy
- 1 cup organic extra virgin olive oil
- 50 drops of lavender essential oil
- 1 ounce organic dried comfrey leaf
- 1 ounce beeswax
- Pour olive oil into a double boiler or small, heavy bottom pot. Add comfrey leaves.
- Heat over low heat for 60 minutes, stirring occasionally. You're looking for gentle heat, not boiling.
- Remove from heat. Strain and compost comfrey, reserving infused oil.
- Melt beeswax in a clean pan over low heat.
- Once melted, add herbal infused oil and lavender essential oil. Mix well.
- Quickly pour salve into tins or glass jars and allow to cool before placing lids on and labeling.
The HANE website notes that “Comfrey contains allantoin, an anti-inflammatory phytochemical that speeds would healing and stimulates growth of new skin cells.” The HANE burn cream recipe also includes one ounce each of dried plantain, calendula and St. John's wort to bump up the healing power a little more.
Photos of Phytophotodermatitis
Just so you can see how the eruptions progressed, I've included some comparison photos below. The image at the top of the post is my left elbow on day three after exposure. 24 hours earlier (48 hours after exposure), there was only one blister.
My left hand at day 3 and day 7 after exposure. Day seven may not look much better, but it feels much better. No more burning and itching.
One last shot. A blister on my right arm that was one of the first to appear that I treated with a plantain poultice followed up by a day of honey and ongoing use of the comfrey salve.
Don't fear the plants, just don't handle them in such a way that you set yourself up for some serious discomfort. Learn from my mistakes. 🙂
You may also find useful:
- 9 Home Remedies for Dry Skin – Soothe Dry and Flaking Skin Naturally
- Grandma Called it Medicine Leaf
- Herbal Antibiotics – the Top 15 Herbal Antibiotics
Originally posted in 2014, updated in 2018.