The term “laurel” can be misleading, as it is used to describe several different plant species with varying levels of toxicity. For this reason, the question of what are the side effects of laurel has no single, simple answer. To understand the risks, it is essential to distinguish between the different types of laurel, their uses, and their potential hazards.
Culinary Bay Laurel (Laurus nobilis)
This is the variety commonly used in cooking to flavor soups, stews, and braised dishes. The culinary bay laurel is native to the Mediterranean and has oval, smooth-edged leaves. Its side effects are mostly related to improper use.
- Ingestion of whole leaves: Unlike other herbs, bay laurel leaves remain hard and leathery even after cooking. Swallowing a whole or large piece of the leaf poses a choking hazard. There are also documented cases of intestinal perforation and obstruction from ingesting the indigestible leaves.
- Essential oil toxicity: The concentrated essential oil derived from bay laurel leaves is toxic and should never be consumed orally. When ingested, it can cause harm to the kidneys, liver, and central nervous system.
- Central nervous system (CNS) effects: In large, medicinal-level doses, bay laurel may cause sleepiness and slow down the CNS. This can be particularly dangerous when combined with sedative medications used during and after surgery.
- Blood sugar effects: High amounts of bay laurel can potentially lower blood sugar levels, which is a concern for people with diabetes.
Highly Toxic Laurels
Many ornamental shrubs and trees are also called laurel, but are extremely poisonous to humans and animals. This includes mountain laurel, cherry laurel, and spurge laurel.
Mountain Laurel (Kalmia latifolia)
All parts of the mountain laurel are highly poisonous, containing the toxic compound andromedotoxin. Even honey made by bees that feed on this plant can be toxic, a condition known as 'Mad Honey' disease. Ingesting any part of this plant is considered unsafe and can lead to severe, even fatal, side effects.
Common symptoms of mountain laurel poisoning include:
- Pain and cold sweats
- Nausea and vomiting
- Diarrhea and abdominal pain
- Numbness, dizziness, and headache
- Fever and loss of vision
- Serious heart and lung problems, and death
Cherry Laurel (Prunus laurocerasus)
This common garden hedge is toxic due to the presence of cyanogenic glycosides, which release cyanide when chewed or digested. Its leaves are serrated, distinguishing them from culinary bay laurel.
Common symptoms of cherry laurel poisoning include:
- Abdominal pain, nausea, and vomiting
- Headache and dizziness
- Reddening of the face
- Decreased respiration and heart palpitations
- Unconsciousness and, in severe cases, respiratory paralysis
Spurge Laurel (Daphne laureola)
Spurge laurel is a shrub with poisonous berries and sap that can cause serious irritation upon contact.
Common symptoms of spurge laurel exposure include:
- Ingestion: Burning sensation in the mouth, followed by thirst, difficulty swallowing, vomiting, diarrhea, and coma.
- Skin contact: Severe skin irritation, blistering, and dermatitis from contact with the sap.
Comparing Laurel Varieties and Their Risks
| Laurel Type | Culinary Use? | Primary Risk | Key Identification Feature |
|---|---|---|---|
Bay Laurel (Laurus nobilis) |
Yes | Choking, intestinal perforation (if swallowed whole); Essential oil toxicity | Smooth, wavy-edged leaves; camphoraceous aroma |
Mountain Laurel (Kalmia latifolia) |
No | Highly toxic (andromedotoxin) in all parts; 'Mad Honey' risk | Leathery, evergreen leaves; no culinary smell |
Cherry Laurel (Prunus laurocerasus) |
No | Cyanide poisoning from leaves and fruit (cyanogenic glycosides) | Serrated leaf edges; crushed leaves smell of almonds |
Spurge Laurel (Daphne laureola) |
No | Severe skin irritation from sap; ingestion causes burning and vomiting | Evergreen shrub with inconspicuous flowers; black berries |
Allergic Reactions and Topical Use
Beyond ingestion risks, certain laurel products can cause allergic reactions through topical application. This is particularly true for laurel essential oils.
- Allergic contact dermatitis: Individuals with sensitivities may experience allergic reactions, including skin redness, itching, and swelling, from topical applications of laurel oil.
- Dilution is key: Laurel oil should always be diluted with a carrier oil before applying it to the skin to minimize irritation. A patch test on a small area of skin is also recommended.
- Photosensitivity: Some natural oils, including bay laurel seed oil, can increase skin sensitivity to sunlight.
Drug Interactions and Special Considerations
Large, medicinal quantities of bay laurel may have interactions with certain medications.
- Sedatives: Bay laurel may slow down the central nervous system. Combining it with sedatives (CNS depressants) can cause excessive sleepiness or breathing problems.
- Diabetes medications: Due to its potential to lower blood sugar, using bay laurel with diabetes medications requires careful monitoring to prevent hypoglycemia.
- Surgery: Discontinue medicinal use of bay laurel at least two weeks before any scheduled surgery.
- Pregnancy and Breastfeeding: The safety of large, medicinal doses during pregnancy and breastfeeding is not reliably known. It is safest to only consume bay laurel in typical food amounts.
Conclusion: Knowledge is Key for Safety
While culinary bay laurel is a beloved cooking ingredient, the name "laurel" can hide serious and potentially fatal dangers. The vast difference in toxicity among species like mountain laurel, cherry laurel, and spurge laurel underscores the importance of proper plant identification. Whether cooking with bay leaves or gardening near ornamental laurels, understanding the specific plant you are dealing with is the most crucial step for ensuring your safety and the safety of your family and pets. Always remove whole bay leaves from cooked dishes and never ingest any part of an unidentified laurel plant.
For more information on medicinal plant safety, consult an authority like the American Botanical Council [https://www.herbalgram.org/resources/herbal-medicine-magazine/view/herbalegram/tekst/198/].
