Phytophotodermatitis happens when certain plant chemicals cause the skin to become inflamed following exposure to sunlight.

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Phytophotodermatitis gets its name from the Greek terms “phyto,” meaning plant, “photo,” meaning light, and “dermatitis,” which refers to skin inflammation.

Also known as lime disease — not the same as the tick-borne illness Lyme disease — phytophotodermatitis causes symptoms that include skin inflammation, itching, and blistering.

This condition happens when a person has exposure to sunlight after coming into contact with a plant to which they are sensitive.

Research suggests that the symptoms of phytophotodermatitis usually begin 24 hours after exposure and peak after 48–72 hours. The symptoms, which can be mild or severe, include:

  • large areas of blistering
  • itching
  • redness or discoloration
  • inflammation
  • pain
  • tenderness
  • a burning sensation
  • crusted patches of skin once the blisters have burst

The patches of blisters usually present in irregular shapes. The patterns represent the areas of the skin that became exposed to the chemical. For example, blisters in a drip pattern may result from exposure to fruit juice. Streaks may indicate that a person brushed their skin against a plant.

Once the blisters begin to heal, usually after 7–14 days, the skin may show signs of darkening, which is known as hyperpigmentation. This stage of phytophotodermatitis, also known as post-inflammatory pigmentation, may last for many weeks or months.

Some people who experience only a very mild inflammatory reaction following sun exposure may not even be aware that they have had a reaction. The hyperpigmentation may be the first clue that they have developed phytophotodermatitis.

Wet skin, sweat, and heat can exacerbate the initial symptoms, while sun exposure can darken skin pigmentation.

Most cases of phytophotodermatitis clear up with minimal intervention. However, treatment is available to reduce pain and shorten the duration of symptoms. Treatment options include:

  • Avoiding reexposure: It is important to take steps to avoid the plant that caused the skin reaction. For many individuals, this may be enough to alleviate the symptoms.
  • Avoiding other skin irritants: It may be helpful to wear cotton clothing and avoid the use of harsh detergents, soaps, and personal care products that may make the symptoms worse.
  • Cold compresses: Placing a cool washcloth on the affected area provides relief.
  • Topical creams: Applying soothing ointments, lotions, and creams to the skin may reduce swelling and itching.
  • Corticosteroids: Topical steroidal creams will reduce inflammation and itching.
  • Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs include aspirin and ibuprofen, and they may help reduce pain and swelling.
  • Prescribed medications: A doctor may prescribe oral corticosteroids or antihistamines for severe symptoms.
  • Reducing sun exposure: Spending less time in the sun, especially when UV rays are at their strongest, may help prevent hyperpigmentation from becoming even darker. Also, a person should always wear sunscreen when they cannot avoid sun exposure.

Severe cases of phytophotodermatitis, which are those involving more than 30% of the skin, may require hospital treatment that includes corticosteroid treatment and IV fluids.

Photochemotherapy is a type of UV treatment that doctors may advise using to treat certain skin-related conditions, such as psoriasis. However, they do not recommend it for phytophotodermatitis because it can worsen hyperpigmentation.

In some cases, phytophotodermatitis can become severe and lead to more serious burns, skin necrosis, and bacterial or fungal infections in the affected area of the skin.

Phytophotodermatitis occurs when someone comes into contact with plant chemicals and then with sunlight. The symptoms typically arise after direct contact with the plant itself.

Many plants and vegetables contain chemical compounds that cause sensitivity to sunlight. Such chemicals are known as photosensitizers. An example of a photosensitizer is psoralen.

Some common plants that contain psoralen include:

  • parsley
  • carrot
  • celery
  • fig
  • citrus fruits
  • garden rue
  • breadnut
  • meadow grass
  • parsnip

Psoralen may also be present in some fragrances and some plant oils, such as oil of bergamot.

On exposure to UVA light, psoralen causes photochemical reactions in the skin. These responses damage skin cells and cause cell death, leading to the symptoms of phytophotodermatitis.

Phytophotodermatitis can affect anyone. However, several factors may increase a person’s risk of experiencing it.

The risk factors include:

  • exposure to certain plants and plant-based products
  • using perfumes or oils that contain particular plant chemicals
  • sunny weather
  • engaging in certain activities

Activities that can trigger it include:

  • canning fruits or vegetables
  • working with produce in a grocery store
  • cooking fruits or vegetables
  • fishing, gardening, hiking, camping, and other outdoor recreational activities that expose a person to both plants and sunlight

People who work in certain professions may also be at higher risk, including:

  • farmers
  • gardeners
  • forest rangers
  • cooks and kitchen staff
  • bartenders
  • canners

Doctors usually diagnose phytophotodermatitis by taking a person’s medical history and carrying out a physical examination. The doctor will ask about recent activities, exposure to plants, sun exposure, and current and previous symptoms. They will also examine the affected skin.

If the doctor is unsure of the diagnosis or wishes to rule out other conditions, they may carry out further tests, such as a patch test or skin biopsy. Mild cases of phytophotodermatitis do not always necessitate medical care. However, if the symptoms are severe or persistent, a person should consult their doctor.

Doctors often misdiagnose phytophotodermatitis, mistaking it for another condition, such as:

  • contact dermatitis
  • cellulitis
  • fungal skin infection
  • burn
  • photosensitivity due to drugs

It may be possible to prevent the inflammatory skin reaction associated with phytophotodermatitis by:

  • identifying the plants that may cause a skin reaction and taking steps to avoid contact with them
  • washing the skin, especially the hands, within 1–2 hours of cooking, spending time outdoors, or coming into contact with plants to remove the plant chemicals from it
  • covering up the skin with suitable clothing when outdoors and in woodland areas
  • wearing gloves when gardening, cooking, or slicing fruits or vegetables
  • using sunscreen before exposing the skin to the sun

Phytophotodermatitis is usually not serious and resolves quickly. Complications are uncommon.

However, recurrent cases of phytophotodermatitis may indicate repeated contact with something that is causing a reaction. A doctor can help a person identify the cause.

Anyone who has symptoms that are severe, recurrent, not improving, or getting worse should speak with a doctor.

Phytophotodermatitis is a condition that happens after a person’s skin comes into contact with chemicals from a plant. The chemicals then react when the person goes out in the sun, and a blistering skin reaction occurs.

This condition is usually mild and resolves on its own, but on rare occasions, it can be severe. People can avoid the condition by identifying the plant to which they are sensitive and avoiding contact with it, as well as limiting their exposure to sunlight. The treatment options to relieve symptoms include creams, corticosteroids, and pain-relieving medications.