Phytophotodermatitis: When plants and light affect the skin
Phytophotodermatitis gets its name from the terms 'phyto' meaning plant, 'photo' meaning light, and 'dermatitis' meaning skin inflammation.
Also known as lime disease (which is not the same as Lyme disease), phytophotodermatitis symptoms include skin inflammation, itching, and blistering.
- Most cases resolve on their own, but some require medical treatment.
- Symptoms include blisters and patches.
- It is often misdiagnosed.
- Avoiding the sun is a method of prevention.
What are the symptoms?
Phytophotodermatitis may be caused by exposure to both plant chemicals and sunlight together. Meadow grass is one plant that may cause this skin reaction.
The symptoms of phytophotodermatitis usually begin 24 hours after exposure and peak between 48-72 hours. Symptoms can be mild or severe and include:
- large areas of blistering
- burning sensation
- crusted patches of skin (once blisters burst)
The patches of blisters are usually irregularly shaped. The patterns represent the areas of the skin that were exposed to the chemical. For example, blisters in the pattern of drips may result from exposure to fruit juice. Streaks may indicate that a person brushed their skin against a plant.
When the initial symptoms subside, usually after 7-14 days, the skin may show signs of darkening, which is known as hyperpigmentation. This stage of phytophotodermatitis, 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.
Causes and risk factors
Citrus fruits and the oils from citrus fruits may cause phytophotodermatitis.
Phytophotodermatitis occurs when someone is exposed to plant chemicals and subsequently exposed to sunlight.
Symptoms typically arise after direct contact with the plant, such as by touching.
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:
- citrus fruits
- common rue
- South African blister bush plant
- meadow grass
Also, it may be present in:
- some fragrances
- some plant oils, such as oil of bergamot
When exposed to UVA light, psoralen causes photochemical reactions in the skin. These responses damage skin cells and cause cell death, leading to the symptoms described above.
Anybody can be affected by phytophotodermatitis, regardless of gender, age, or race. However, several factors may increase the risk of experiencing phytophotodermatitis.
- exposure to certain plants and plant-based products
- using perfumes or oils that contain certain plant chemicals
- sunny weather
- engaging in certain activities
Activities that can trigger it include:
- outdoor games
Certain professions can increase the risk, such as:
- forest rangers
- cooks and kitchen staff
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 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 symptoms are severe or persist, a person should consult their doctor.
It should be noted that phytophotodermatitis is often misdiagnosed. It may be mistaken for:
- atopic dermatitis
- chemical burns
- fungal skin infections
- other forms of contact dermatitis
A cold compress applied to the skin may help to treat phytophotodermatitis.
Most cases of phytophotodermatitis clear up with minimal intervention. Treatment aims to reduce pain and shorten the duration of symptoms. Treatment options include:
- Avoiding re-exposure - it is important to take steps to avoid the plant that caused the skin reaction. For many individuals, this may be enough to alleviate 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 which may make 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 painkillers - non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, 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 highest, may help prevent hyperpigmentation from becoming even darker. Also wearing sunscreen when you cannot avoid sun exposure.
- Time - there is no cure for hyperpigmentation of the skin, except to wait for it to fade.
Severe cases of phytophotodermatitis, or those involving more than 30 percent of the skin, may require hospital treatment that includes corticosteroid treatment and intravenous (IV) fluids.
Photochemotherapy is a type of UV treatment that is used for certain skin diseases, such as psoriasis. However, it is not recommended for phytophotodermatitis because it can make hyperpigmentation even darker.
Skin whitening should also be avoided in cases of phytophotodermatitis because this procedure has not been proven to help the condition.
In some cases, phytophotodermatitis can lead to the following complications:
- bacterial and fungal infection of the skin
- severe allergic reaction
- recurrence of symptoms on subsequent exposure
The inflammatory skin reaction associated with phytophotodermatitis may be prevented by:
- Identifying the plants that are skin allergens or irritants and take steps to avoid contact with them.
- Washing hands with plain soap and water following cooking, spending time outdoors, or contact with plants. Washing helps remove the plant chemicals from the skin.
- Covering up the skin with suitable clothing when outdoors and in woodland areas.
- Wearing gloves when gardening.
- Wearing food preparation gloves when cooking or slicing citrus fruits.
- Using sunscreen before exposing skin to the sun.
See a doctor if symptoms are:
- not improving
- getting worse
Phytophotodermatitis is usually not serious and resolves quickly. Complications are uncommon. Recurrent cases of phytophotodermatitis suggest that the offending plant has not been identified.