Phytophotodermatitis: When Lime Juice and Sunlight Leave Dark Marks on Your Skin

6 days ago

3 min read

A few hours to a day after squeezing limes, peeling kaffir limes or cooking outdoors, your skin breaks out in a red, stinging, blistering rash in odd shapes that look like drips or fingerprints, followed by dark marks that last for months. This is the classic picture of phytophotodermatitis, a skin reaction to certain plants combined with sunlight. Many people mistake it for an allergy, but it is actually a reaction that can happen to almost anyone.

What is phytophotodermatitis?

Phytophotodermatitis is a phototoxic reaction (not an allergy) that occurs when skin comes into contact with furocoumarins (psoralens) found in certain plants and that area is then exposed to sunlight (UVA rays). When these substances combine with light, they damage skin cells, causing inflammation and stimulating extra pigment production, which leads to both a burn-like rash and dark marks afterwards.

Common plants and situations

The triggering substances are found in:

Limes, kaffir limes, oranges and lemons (the most common cause, especially in people who cook, bartenders, or people squeezing lime at the beach)
Celery, parsley, wild carrot and figs
Some garden plants handled while gardening

Because this is a phototoxic reaction that can happen to anyone, you do not need to have been "allergic" before. Having enough of the substance plus sun exposure is all it takes.

Symptoms to watch for

Red, stinging or blistered skin appearing within a few hours to 1–2 days after sun exposure
Unusually shaped rashes in lines, drips, or patterns like fingerprints or running liquid, following where the substance touched the skin
Followed by dark marks (hyperpigmentation) that may last from several weeks to several months
Usually on sun-exposed areas such as the hands, arms and legs, or where fruit juice dripped onto the skin

Diagnosis

A dermatologist can usually make the diagnosis from the history of plant contact plus sun exposure together with the characteristic shape of the rash. Special tests are generally not needed, but seeing a doctor helps rule out other conditions such as contact dermatitis, infections or other types of sun-triggered rashes, and helps plan care for troublesome dark marks.

Treatment approach

Acute stage (red rash/blisters): apply cold compresses, avoid sun on the affected area, and use anti-inflammatory topical medication as advised by a doctor. See a doctor if blistering is severe.
Dark mark stage: the key is strict sun protection (sunscreen and sun avoidance), because sun exposure makes the marks darker and last longer. Most marks fade on their own over time. For dark or bothersome marks, a doctor may consider skin-brightening agents or additional treatments.
Prevention: wash your hands and skin thoroughly after touching limes or these plants before going out in the sun, and apply sunscreen regularly.

Note: The treatment information is general knowledge. The choice of medications and products for dark marks should be made under a doctor's guidance.

When to see a dermatologist

See a doctor if:

The rash is heavily blistered, severely painful or stinging, or covers a large area
You are not sure whether it is phytophotodermatitis or another type of sun-triggered rash
You have dark marks that bother you and want safe ways to help them fade sooner

Frequently asked questions (FAQ)

Is phytophotodermatitis an allergy to limes?

No. It is a phototoxic reaction caused by substances in the plant reacting with sunlight, so it can happen to anyone, even people who have never had an allergy.

Will the dark marks go away, and how long does it take?

Most dark marks fade on their own within several weeks to several months. Strict sun protection helps them fade sooner and keeps them from getting darker.

How can I prevent it when cooking or at the beach?

Wash lime or kaffir lime juice off your hands and skin thoroughly before going into the sun, and apply sunscreen regularly to exposed areas.

Cared for by the dermatology team at Siam Dermatology (formerly Dr. Pat Skin Clinic)

A specialist skin clinic in Samut Prakan, caring for everything from acute rashes to the safe treatment of dark marks.

📞 Call +66 61 448 7000 · LINE: @siamderm

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed July 16, 2026