Phytophotodermatitis

Phytophotodermatitis is a skin reaction that happens when certain plant chemicals and sunlight mix on your skin. The reaction causes irritation that looks and feels like a burn.

It isn’t an allergy. It’s a type of contact dermatitis. This is a reaction that happens after something touches your skin. Specifically, it’s a chemical reaction between plant oils and sunlight (UVA rays). Symptoms can include skin discoloration, blisters, swelling or a rash.

You can manage this at home. But a healthcare provider can help, too.

Symptoms of phytophotodermatitis

Phytophotodermatitis only affects the parts of your skin that touch the plant or plant oils. This can be from direct touch or spread from hands, other body parts or clothing. Symptoms can look different for each person, but they may include:

• A rash or small blisters
• Discoloration (red, purple or patches darker than your natural tone)
• Itchy or irritated skin
• Streaks or round spots that look like drops or splashes
• Swelling and mild pain

Symptoms usually show up one to two days after your skin touches a plant and then gets sun exposure.

Phytophotodermatitis causes

Phytophotodermatitis happens when a chemical from certain plants touches your skin and reacts after mixing with sunlight.

These plants make a natural chemical called furanocoumarin (pronounced “fyoo-rah-no-KOO-muh-rin”). It helps protect the plant from bugs and germs. You can find this chemical on the leaves, stems and fruits of many plants.

When sunlight hits the chemical, it becomes active. If it’s on your skin, it can irritate or burn. This causes discoloration, swelling and other symptoms.

What plants cause phytophotodermatitis?

Many plants can cause this skin reaction. Some of the most common include:

• Anise
• Bergamot
• Celery
• Dill
• Fennel
• Figs (especially the sap)
• Hogweed
• Limes and other citrus fruits
• Parsley
• Parsnips and carrots

Risk factors of phytophotodermatitis

Anyone can develop a skin reaction if their skin touches plant chemicals and then gets sunlight. You may have a higher risk if you:

• Handle fruits and vegetables in a bar, kitchen or restaurant
• Pick fruits or vegetables
• Trim weeds, trees or shrubs
• Work or play in a garden or orchard
• Camp and hike

Can phytophotodermatitis spread?

The rash itself isn’t contagious — you can’t spread it to another person by touch. But someone else could get a similar rash if they touch the same plant and then go out in the sun.

The rash can also appear on new areas of your own skin if the plant’s sap or juice spreads. For example, if you get fig sap on your hands, wipe your thigh and then go outside, both spots could develop a rash.

How doctors diagnose phytophotodermatitis

A healthcare provider can usually diagnose phytophotodermatitis after examining your skin and learning more about your medical history.

In rare cases, your provider may order a skin biopsy to confirm the diagnosis. This test involves removing a small sample of skin and looking at it under a microscope. You don’t usually need this if it’s clear that you had plant contact and sun exposure about a day before symptoms started.

Phytophotodermatitis treatment

You can often treat this skin condition at home. Try these tips:

• Put a cool, wet cloth on the rash for 10 to 15 minutes. This eases pain and swelling.
• Wash your skin with mild soap and warm water. Pat it dry with a clean towel.
• Apply a thin layer of plain petroleum ointment. Cover it with a clean bandage.
• Keep the area out of sunlight. When outside, cover it with clothing or use sunscreen.

Over-the-counter medications can also help relieve symptoms. Try:

• A pain reliever (for mild pain)
• An oral antihistamine (for itching)
• A 1% hydrocortisone cream (for itching and discoloration)
• Calamine lotion (for itching)

If it isn’t getting better, is very painful or looks infected (more discoloration, warmth, pus, fever), contact a healthcare provider. They may prescribe a stronger steroid cream to reduce inflammation and help it heal faster.

How long does phytophotodermatitis last?

Your skin usually heals on its own within two to four weeks. Most people don’t need medical treatment unless symptoms are severe. At-home care can relieve pain, itching and swelling.

After the rash fades, your affected skin may stay darker or lighter for a few months. This discoloration is temporary and will slowly return to normal. If the color changes bother you or don’t go away, talk to a dermatologist for advice or treatment options.

Try your best to avoid popping blisters, scratching or picking at the rash. This can cause open sores, infections or scars.

Can phytophotodermatitis be prevented?

Most cases happen by accident, but there are ways to lower your risk:

• Be aware. Learn which plants can cause this reaction and try to avoid direct contact with them.
• Cover your skin. Wear long sleeves, pants and gloves when gardening, trimming plants or picking fruits and vegetables.
• Use sunscreen. Apply sunscreen before going outdoors.
• Wash up. Wash your hands and skin well with soap and water after handling citrus fruits or other plants.

Sun exposure within hours of plant contact triggers the reaction. If you wash your skin quickly after touching plants, you may be able to prevent some symptoms.