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Phytodermatoses
When plants irritate, cause allergy… or react with sunlight
In this sheet
3 essential points
Phytophotodermatitis is usually not an allergy
Some plants contain furocoumarins. On skin subsequently exposed to UVA, they can cause redness, burning, swelling or blisters, followed by brown pigmentation. Previous sensitisation is not required.
True contact allergy to plants also exists
After sensitisation, further exposure may trigger delayed eczema. Sesquiterpene lactones in many Asteraceae/Compositae are classic plant allergens.
The shape of the lesions often tells the story
Drip marks, fingerprints, splashes or clothing boundaries may suggest phytophotodermatitis. Photograph lesions early.
Main types of phytodermatosis
- Type
- Irritant
- Mechanism
- Direct damage to the skin
- Typical appearance/timing
- Burning, redness and cracks; often rapid.
- Type
- Allergic contact
- Mechanism
- Delayed immune reaction
- Typical appearance/timing
- Eczema and itching; often 24–72 hours after contact.
- Type
- Phytophotodermatitis
- Mechanism
- Phototoxic plant + UVA
- Typical appearance/timing
- Redness/burning ± blisters, then pigmentation.
- Type
- Contact urticaria
- Mechanism
- Immediate reaction, sometimes IgE-mediated
- Typical appearance/timing
- Wheals/urticaria within minutes.
- Type
- Mechanical
- Mechanism
- Thorns, hairs, trichomes…
- Typical appearance/timing
- Localised pain or inflammation.
| Type | Mechanism | Typical appearance/timing |
|---|---|---|
| Irritant | Direct damage to the skin | Burning, redness and cracks; often rapid. |
| Allergic contact | Delayed immune reaction | Eczema and itching; often 24–72 hours after contact. |
| Phytophotodermatitis | Phototoxic plant + UVA | Redness/burning ± blisters, then pigmentation. |
| Contact urticaria | Immediate reaction, sometimes IgE-mediated | Wheals/urticaria within minutes. |
| Mechanical | Thorns, hairs, trichomes… | Localised pain or inflammation. |
Phytophotodermatitis: citrus fruits, fig trees, hogweed and perfumes
Which plants may be involved?
- Plant/family
- Lime
- Typical exposures
- Cocktails, cooking and drinks on the beach.
- Plant/family
- Lemon / some citrus fruits
- Typical exposures
- Juice, zest and cooking.
- Plant/family
- Bergamot
- Typical exposures
- Some perfumes or scented oils.
- Plant/family
- Fig tree
- Typical exposures
- Leaves and sap during gardening.
- Plant/family
- Parsnip, celery, parsley
- Typical exposures
- Cooking, market gardening and gardening.
- Plant/family
- Rue
- Typical exposures
- Gardening.
- Plant/family
- Giant hogweed
- Typical exposures
- Outdoor contact; sometimes severe phototoxic burns.
| Plant/family | Typical exposures |
|---|---|
| Lime | Cocktails, cooking and drinks on the beach. |
| Lemon / some citrus fruits | Juice, zest and cooking. |
| Bergamot | Some perfumes or scented oils. |
| Fig tree | Leaves and sap during gardening. |
| Parsnip, celery, parsley | Cooking, market gardening and gardening. |
| Rue | Gardening. |
| Giant hogweed | Outdoor contact; sometimes severe phototoxic burns. |
‘Lime disease’: lime plus sunlight
Typical scenario: squeezing limes or preparing cocktails → juice on the hands/forearms → sun exposure → reaction in the following hours. The terms ‘margarita burn’ and ‘margarita photodermatitis’ are also used.
The lesion pattern can provide a clue
- vertical drip marks;
- fingerprints or handprints;
- irregular splashes;
- areas covered by clothing spared.
The appearance may resemble a burn, infection or contact dermatitis. In children, very geometric patterns can even be misleading.
Fig tree and giant hogweed
Fig-tree sap and leaves (Ficus carica) can cause blistering reactions that are sometimes extensive. Giant hogweed can cause genuine phototoxic burns after sun exposure.
When should prompt advice be sought?
Extensive blisters, severe pain, involvement of the face or eyes, or a large area of skin.
Berloque dermatitis
Berloque dermatitis is a historical photodermatosis linked to some scented preparations containing bergamot furocoumarins followed by sun exposure. It may cause pigmented streaks on the neck or neckline, sometimes preceded by redness or blisters.
True plant allergies, exposed occupations and assessment
Contact allergy to plants: which allergens?
Allergic contact dermatitis to plants more commonly causes itchy eczema with redness, vesicles and scaling. It requires previous sensitisation.
- Exposure
- Asteraceae/Compositae: chrysanthemum, chamomile, arnica, yarrow…
- Allergen/specific feature
- Sesquiterpene lactones; sometimes airborne dermatitis of the face, neck and forearms.
- Exposure
- Garlic/onion
- Allergen/specific feature
- Sulphur compounds, including diallyl disulfide; mainly on highly exposed hands.
- Exposure
- Tulip/Alstroemeria
- Allergen/specific feature
- Tulipalin A; classic in some florists.
- Exposure
- Primrose
- Allergen/specific feature
- Primin; a classic plant allergen.
| Exposure | Allergen/specific feature |
|---|---|
| Asteraceae/Compositae: chrysanthemum, chamomile, arnica, yarrow… | Sesquiterpene lactones; sometimes airborne dermatitis of the face, neck and forearms. |
| Garlic/onion | Sulphur compounds, including diallyl disulfide; mainly on highly exposed hands. |
| Tulip/Alstroemeria | Tulipalin A; classic in some florists. |
| Primrose | Primin; a classic plant allergen. |
Occupation may be the key
Gardeners, florists, market gardeners, farmers, forestry workers, cooks and catering staff may develop irritant, allergic or immediate phytodermatoses. Several mechanisms can coexist.
Contact urticaria and protein contact dermatitis
Some plants, fruits, vegetables or plant products can cause itching, raised wheals or swelling within minutes. In people who handle fresh food every day at work, protein contact dermatitis may combine chronic hand eczema with rapid flares after contact.
How is the investigation conducted?
- Question
- What did you touch?
- What to record
- Plant, fruit/vegetable, leaves, stems, sap, juice or zest.
- Question
- Where and when?
- What to record
- Garden, kitchen, work, holiday or beach; approximate date and time.
- Question
- Sunlight afterwards?
- What to record
- UVA exposure in the following hours.
- Question
- Any product applied?
- What to record
- Perfume, essential oil, cosmetic or homemade plant preparation.
- Question
- What did the lesions look like?
- What to record
- Drip marks, patches, blisters, eczema or urticaria; take an early photograph if possible.
| Question | What to record |
|---|---|
| What did you touch? | Plant, fruit/vegetable, leaves, stems, sap, juice or zest. |
| Where and when? | Garden, kitchen, work, holiday or beach; approximate date and time. |
| Sunlight afterwards? | UVA exposure in the following hours. |
| Any product applied? | Perfume, essential oil, cosmetic or homemade plant preparation. |
| What did the lesions look like? | Drip marks, patches, blisters, eczema or urticaria; take an early photograph if possible. |
Which tests may be offered?
- Typical phytophotodermatitis: diagnosis is mainly clinical; blood tests are generally unnecessary.
- Suspected contact allergy: patch tests with appropriate allergens (sesquiterpene lactones, primin, tulipalin A, diallyl disulfide, etc.).
- Immediate reaction: skin prick testing, prick-to-prick testing or other immediate investigations depending on the history.
What to do, prevention and when to seek advice
After contact with a phototoxic plant
How is phytophotodermatitis treated?
Most forms are treated symptomatically: stopping exposure, photoprotection, local care, emollients and sometimes topical corticosteroids depending on the degree of inflammation and medical advice. Very extensive or blistering forms may require more substantial medical care.
Pigmentation may persist
Brown pigmentation may persist for several weeks after the inflammation has resolved. This does not mean that the reaction is continuing.
Preventing another reaction
- Identify the plant or product involved.
- Wash skin promptly after contact with phototoxic sap, juice or zest.
- Avoid sunlight/UVA on the exposed area; wear suitable gloves and clothing for some activities.
- Do not deliberately apply a suspected plant to the skin.
Differential diagnosis: a plant is not always responsible
Depending on its appearance, a phytodermatosis may resemble allergic eczema, a thermal or chemical burn, a skin infection, shingles, a blistering disorder, insect bites or a drug eruption.
Common misconceptions
- Misconception
- ‘A reaction to a plant must be an allergy.’
- SOS Allergo guidance
- False: irritation and phototoxicity are common.
- Misconception
- ‘You must already be allergic to react to lime plus sunlight.’
- SOS Allergo guidance
- False: phytophotodermatitis is mainly phototoxic.
- Misconception
- ‘Lime disease means Lyme disease.’
- SOS Allergo guidance
- No: here, lime means the citrus fruit.
- Misconception
- ‘A drip-shaped mark must be caused by a chemical.’
- SOS Allergo guidance
- Phytophotodermatitis can have exactly this pattern.
- Misconception
- ‘I can patch test the plant myself.’
- SOS Allergo guidance
- No: some plants are irritant or sensitising.
| Misconception | SOS Allergo guidance |
|---|---|
| ‘A reaction to a plant must be an allergy.’ | False: irritation and phototoxicity are common. |
| ‘You must already be allergic to react to lime plus sunlight.’ | False: phytophotodermatitis is mainly phototoxic. |
| ‘Lime disease means Lyme disease.’ | No: here, lime means the citrus fruit. |
| ‘A drip-shaped mark must be caused by a chemical.’ | Phytophotodermatitis can have exactly this pattern. |
| ‘I can patch test the plant myself.’ | No: some plants are irritant or sensitising. |
Before your appointment: the SOS Allergo checklist
- date lesions started and activities in the previous 24–48 hours;
- gardening, cooking, work or holiday; sunlight/UVA after contact;
- plant, fruit or vegetable handled; sap, leaves, juice or zest;
- perfume, essential oil or cosmetic applied; occupation;
- immediate or delayed reaction; mainly burning or itching;
- photographs of lesions at different stages and a photograph/name of the plant if available.
Key points
Not every reaction to a plant is an allergy. With an unusual lesion, the most useful question is often: ‘What did I touch before going into the sun?’ The pattern, timing and a photograph of the plant often avoid unnecessary tests and help prevent another reaction.
You may also want to read
Keep the sheet
Download the validated patient document to read again or prepare for your appointment.
Main references
- Bălăceanu-Gurău B, et al. New Insights Concerning Phytophotodermatitis Induced by Phototoxic Plants. Life. 2024;14:1019.
- Lacroix G, Samaran Q, Herlin C. Phytophotodermatitis: An under-recognized diagnostic pitfall in chemical burns. Ann Chir Plast Esthet. 2026.
- Jiang SY, et al. Lime-Induced Phytophotodermatitis. J Allergy Clin Immunol Pract. 2024.
- Paulsen E. The sesquiterpene lactone mix. Contact Dermatitis. 2023;89:434–441.
- Uter W, et al. ESCD Guideline for Diagnostic Patch Testing - Update 2026. Contact Dermatitis. 2026;95:237–275.
- Wang L, et al. Berloque dermatitis induced by “Florida water”. Cutis.
- Sasseville D. Phytodermatitis. J Cutan Med Surg. 1999.
This sheet provides information and helps you prepare for a consultation. It does not replace medical advice or instructions from a specialist team.
Scientific review: September 2026 · sosallergo.fr