Giant hogweed Toxic?

Updated 2026-03-06| 4 min read| 4,065 found this helpful

All plant parts, especially sap, contain phototoxic furanocoumarins that trigger adverse reactions when exposed to UV light

Contact toxicity to animals is generally low, but ingestion can cause ulcerative lesions in sensitive species like goats

Exposure requires strict sunlight avoidance and targeted topical treatment to reduce inflammation and secondary infection risk

FAQ

Is Giant hogweed toxic to Humans?

Phototoxic contact dermatitis, blistering, and long-term skin discoloration if sap-contacted skin is exposed to sunlight (Moderate)

Is Giant hogweed toxic to Cats?

No specific documented symptoms; potential for mild phototoxic dermatitis on bare, unpigmented skin contact (Low)

Is Giant hogweed toxic to Dogs?

Phototoxic contact dermatitis on sparsely furred or unpigmented skin areas (Low)

Is Giant hogweed toxic to Horses?

No specific documented symptoms; potential for mild phototoxic dermatitis on hairless skin contact (Low)

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Toxicity Details

Humans

Moderate

Phototoxic contact dermatitis, blistering, and long-term skin discoloration if sap-contacted skin is exposed to sunlight

Cats

Low

No specific documented symptoms; potential for mild phototoxic dermatitis on bare, unpigmented skin contact

Dogs

Low

Phototoxic contact dermatitis on sparsely furred or unpigmented skin areas

Horses

Low

No specific documented symptoms; potential for mild phototoxic dermatitis on hairless skin contact

Toxicity Snapshot

Toxic PartsWhole plant, especially the sap

Exposure RouteDirect skin contact with plant sap, ingestion of plant material

Toxic CompoundsBergapten; Xanthotoxin; Psoralen; Imperatorin; Angelicin; Isopimpinellin; Peucedanin; Oxypeucedanin; Ostruthol; Isoimperatorin; Pimpinellin; Isobergapten; Marmesin; Phellopterin; Sphondin; Apterin; Archangelin

First Aid & Prevention

First 30 Minutes

• Immediately rinse exposed skin with large volumes of cold soapy water to remove residual sap
• Cover all affected areas completely to block UV/sunlight exposure for a minimum of 48 hours
• If ingested, rinse the mouth thoroughly with cool water, do not induce vomiting unless directed by a professional

Contact Vet Immediately

• If your pet develops blistering, ulcerations, or visible pain after contact or ingestion
• If your pet shows signs of stomatitis (drooling, difficulty eating, oral redness) after ingesting plant material
• If skin reactions persist or worsen 24 hours after initial exposure

Prevention

• Learn to identify giant hogweed and avoid contact in overgrown, wild, or riparian areas
• Wear long sleeves, waterproof gloves, and eye protection if handling or removing suspected giant hogweed
• Restrict pet access to known giant hogweed growth sites to prevent accidental contact or ingestion

Treatment & Prognosis

• Apply topical antibiotic and glucocorticoid ointments to affected areas as directed by a medical/vet professional
• Administer analgesics to manage pain associated with lesions or ulcerations
• Strictly avoid all sunlight/UV exposure to affected areas until reactions fully resolve

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Professional Toxicology

Scientific NameHeracleum mantegazzianum Sommier & Levier

AliasesHogweed、Cartwheel flower plant、Cow parsley、Riesen-Bärenklau、Herkulesstaude、Herkuleskraut、Berce du Caucase、Berce de Mantegazzi、Panace di Mantegazzi、Panace di Mantegazza、Panace gigante

Toxicity Grade

HumansModerate

CatsLow

DogsLow

HorsesLow

Target Organs

SkinOral mucous membranesEpidermis

Mechanism of Action

• Furanocoumarin compounds absorb UV light, triggering oxidative damage to skin cell DNA and membranes to cause phototoxic reactions

• Ingestion causes direct mucosal irritation, leading to ulcerative lesions in sensitive species like goats

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: Phototoxic effects observed after contact or exposure

Sheep: Phototoxic effects observed after contact or exposure

Goats: Ulcerative stomatitis occurs after ingestion of giant hogweed plant material

Poultry: Phototoxic effects observed; ducklings develop contact dermatitis on unpigmented beaks

Confusion Risk

The following plants look similar and may be confused:

Common hogweed Heracleum sphondylium

Visually similar to giant hogweed but smaller in stature; also contains furanocoumarins and may cause milder phototoxic reactions

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Related Toxic Plants

Poison hemlock

Conium maculatum

Severe toxicity, fatal if ingested by humans or animals

Water hemlock

Cicuta maculata

Severe toxicity, highly fatal to all species even in small doses

Wild parsnip

Pastinaca sativa

Moderate toxicity, causes phototoxic contact dermatitis similar to giant hogweed

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Data Sources

1. CliniTox (Universität Zürich)

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.