The genus Salvia, commonly known as sage, is a large and diverse group of nearly 1,000 species belonging to the mint family (Lamiaceae). Found worldwide, these plants have a long history of use for medicinal, culinary, and ornamental purposes. While most species are harmless, a few chemically distinct exceptions raise questions about toxicity. Understanding the risks requires differentiating between widely cultivated varieties and rare species that contain compounds capable of causing physical or psychoactive harm.
The Safe Majority: Culinary and Ornamental Sages
The species most frequently encountered in gardens and kitchens are generally considered safe for human and pet consumption in typical amounts. Salvia officinalis (Common Sage) is prized for its robust flavor and traditional medicinal applications. Salvia sclarea (Clary Sage) is often cultivated for its essential oil used in aromatherapy and perfumery.
Popular ornamental species, such as Salvia splendens and Salvia greggii (Autumn Sage), are grown for decorative appeal. These widely available salvias pose no threat, as their compounds are either non-toxic or present in concentrations too low to cause adverse effects during normal use.
Identifying Truly Toxic Salvia Species
A small subset of Salvia species contains potent compounds that cause traditional physical toxicity, distinct from mind-altering effects. These species are rarely found in commercial nurseries or used in cooking, but they remain a concern for foragers. The physical danger often comes from diterpenes, complex organic compounds that can harm internal organs.
Salvia reflexa (Lance-leaf Sage) is one example, containing diterpenes like salviarin and rhyacophiline. These compounds have been shown to cause acute hepatic necrosis in livestock. Although human toxicity data is limited, the presence of these powerful compounds indicates a genuine risk of organ distress or failure if ingested.
Psychoactive vs. Physical Toxicity: The Case of Salvia Divinorum
Salvia divinorum is the species most often associated with the term “poisonous,” but its risk is primarily psychoactive, not physically lethal. Native to the cloud forests of Oaxaca, Mexico, this plant has a history of use in shamanic rituals. Its unique effects stem from its active compound, salvinorin A, a potent, non-nitrogenous diterpene.
Salvinorin A acts as a highly selective agonist at the kappa-opioid receptor in the brain, distinct from classical psychedelics like LSD. The effects include intense, short-lived hallucinations and a dissociative state. This poses a behavioral risk due to impaired judgment and coordination, rather than causing organ failure. The substance’s legal status is variable, being controlled in many regions due to its powerful psychotropic properties.
Mechanisms of Harm and Symptoms of Ingestion
Harm from Salvia species results from two primary chemical mechanisms: diterpenes in rare toxic species and thujone in common species used excessively. The rare toxic species contain diterpenes that cause severe liver damage, leading to symptoms like acute hepatic necrosis, as seen in animal studies. Consumption of these plants must be treated as a serious poisoning event.
A different mechanism involves thujone, found in higher concentrations in the essential oil of S. officinalis (Common Sage). Thujone is a neurotoxin that acts as an antagonist on the GABA-A receptor in the brain, potentially causing excitation and convulsions. Excessive use of common sage, especially concentrated extracts or oils, can lead to vomiting, nausea, diarrhea, dizziness, and neurological effects. Any ingestion of an unknown or toxic Salvia species resulting in severe gastrointestinal distress, neurological symptoms, or confusion requires immediate consultation with poison control or emergency medical services.