Common Evening-Primrose Toxic?

Updated 2026-03-06| 2 min read| 1,650 found this helpful

All plant parts are confirmed non-toxic to humans, cats, dogs, and horses, with no documented poisoning cases

Despite being non-poisonous, the plant is not suitable for use as a primary feed source for any animal species

Misidentification with other Oenothera species poses no toxicity risk, as all related Oenothera taxa are non-toxic

FAQ

Is Common Evening-Primrose toxic to Humans?

No toxic symptoms expected from normal exposure; very large ingestion may cause mild, temporary gastrointestinal upset (Non-toxic)

Is Common Evening-Primrose toxic to Cats?

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools (Non-toxic)

Is Common Evening-Primrose toxic to Dogs?

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools (Non-toxic)

Is Common Evening-Primrose toxic to Horses?

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools (Non-toxic)

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Toxicity Details

Humans

Non-toxic

No toxic symptoms expected from normal exposure; very large ingestion may cause mild, temporary gastrointestinal upset

Cats

Non-toxic

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools

Dogs

Non-toxic

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools

Horses

Non-toxic

No documented toxic effects; excessive ingestion may lead to minor digestive discomfort such as loose stools

Toxicity Snapshot

Toxic PartsNo toxic parts identified; entire plant is non-poisonous, though not recommended for use as animal feed

Exposure RouteNo toxic exposure routes confirmed; ingestion, skin contact, or inhalation do not cause poisoning

Toxic CompoundsGamma-linolenic acid (GLA); Linoleic acid; Vitamin E; Tannins

First Aid & Prevention

First 30 Minutes

• Rinse mouth with clean water if large quantities of the plant are ingested
• Monitor for mild signs of digestive upset including bloating or loose stools
• Offer small sips of fresh water to reduce any potential gastrointestinal irritation

Contact Vet Immediately

• If your pet shows persistent vomiting, diarrhea, or lethargy after ingesting large amounts of the plant
• If the ingested quantity is unknown or the animal has pre-existing chronic digestive conditions
• If you cannot confirm the plant is definitely an Oenothera species and suspect misidentification

Prevention

• Do not use common evening-primrose as a primary feed source for livestock or companion animals
• Keep evening primrose dietary supplements out of reach of pets to avoid accidental overconsumption
• Confirm plant identification before allowing animals to graze in areas with wild Oenothera growth

Treatment & Prognosis

• Only supportive care is required for any mild digestive symptoms
• No specific antidote is needed as no toxic compounds are present in the plant
• Administer probiotics if digestive upset persists for more than 24 hours

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Professional Toxicology

Scientific NameOenothera biennis aggr. (synonyms: Oenothera biennis L., Oenothera fallax Renner, Oenothera glazioviana Micheli, Oenothera lamarckiana auct., Oenothera erythrosepala Borbás, Oenothera pycnocarpa G.F.Atk. & Bartlett, Oenothera stucchii Soldano)

AliasesLarge-flowered Evening-Primrose、Zweijährige Nachtkerze、Gewöhnliche Zweijährige Nachtkerze、Rapontikawurzel、Onagre bisannuelle、Onagre de Glaziou、Enagra comune、Enagra di Glaziou

Toxicity Grade

HumansNon-toxic

CatsNon-toxic

DogsNon-toxic

HorsesNon-toxic

Target Organs

No organs are targeted by toxic compounds, as the plant is confirmed non-poisonous

Mechanism of Action

• No toxic mechanisms identified, as the plant contains no compounds that cause harm to humans or common domestic animals

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Cattle: Non-toxic, but excessive ingestion may cause mild rumen upset; not suitable as a primary feed source

Sheep: Non-toxic, no reported poisoning cases; avoid use as a sole forage source to prevent digestive imbalance

Poultry: Non-toxic, small quantities can be safely included in forage mixes without adverse effects

Confusion Risk

The following plants look similar and may be confused:

Other Evening-Primrose species Oenothera spp.

Visually similar to other Oenothera species with shared bright yellow four-petaled flowers and lanceolate leaf morphology; all related Oenothera species are non-toxic, so misidentification poses no poisoning risk

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Related Toxic Plants

Floating Water Primrose

Ludwigia peploides

Low toxicity, may cause nitrate poisoning in livestock if ingested in very large quantities

Farewell-to-Spring

Clarkia amoena

Low toxicity, contains minor irritant compounds that may cause oral or gastrointestinal discomfort

Narrowleaf Willowherb

Epilobium angustifolium

Low toxicity, may cause mild digestive upset in sensitive animals when consumed in excess

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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.