The Solanaceae plant family, commonly known as nightshades, includes both common food sources like tomatoes, potatoes, and eggplants, and highly toxic species such as deadly nightshade. Understanding the distinctions between harmless and harmful nightshades is crucial for safety.
Identifying Nightshade Plants
Identifying nightshade plants can be challenging, as the family includes both edible and toxic varieties. Deadly nightshade (Atropa belladonna) is a highly poisonous perennial. Its leaves are oval-shaped, and its flowers are bell-shaped and dull purple with greenish tinges. The fruits are shiny black berries, approximately 0.5 inches in diameter, that mature from green and are often surrounded by five sepals.
Another toxic member, bittersweet nightshade (Solanum dulcamara), grows as a vine or woody shrub. Its flowers are star-shaped with five purple petals and prominent yellow anthers. The berries ripen from green to orange, eventually turning bright red. Black nightshade (Solanum nigrum) has small, white, star-shaped flowers and produces clusters of berries that transition from green to black or purplish-black when mature. Due to potential confusion, it is safest to avoid touching or ingesting any wild plant unless its identity is absolutely certain.
How Nightshade Affects the Body
The toxic effects of certain nightshade plants, particularly deadly nightshade, stem from compounds called tropane alkaloids. These include atropine, scopolamine, and hyoscyamine. These alkaloids interfere with the nervous system by blocking the activity of acetylcholine, a neurotransmitter. This disruption can lead to severe physiological responses.
Symptoms of nightshade poisoning affect multiple bodily systems. Neurological effects include dilated pupils, blurred vision, confusion, hallucinations, and delirium. Cardiac symptoms include a rapid heartbeat. Gastrointestinal distress, including dry mouth, nausea, vomiting, diarrhea, abdominal pain, and constipation, can also occur. In severe cases, poisoning can lead to seizures, coma, respiratory failure, and even death.
Factors Influencing Toxicity
Determining the precise amount of nightshade that can be deadly to humans is complex, as several factors influence its toxicity. The species of nightshade plays a role, with Atropa belladonna being among the most toxic plants. Black nightshade (Solanum nigrum) can be poisonous, but its toxicity is generally lower, especially when berries are fully ripe. Bittersweet nightshade (Solanum dulcamara) also contains toxic compounds, with varying effects.
The concentration of toxic alkaloids varies within different parts of the same plant. For Atropa belladonna, all parts contain tropane alkaloids, but roots often have the highest concentration, followed by leaves, then berries. Berries, despite sometimes containing lower concentrations, pose a risk, particularly to children, due to their attractive appearance and deceptively sweet taste. Just two Atropa belladonna berries can be fatal to a child, and 10 to 20 berries can be lethal for an adult. Even a single leaf can contain enough alkaloids to be fatal.
Individual susceptibility also impacts poisoning severity. Factors such as age, body weight, overall health, and metabolic rate influence how a person reacts. Children and the elderly are more vulnerable. While cooking can reduce certain toxins in some nightshade species, it is not a reliable method for detoxifying highly poisonous varieties like Atropa belladonna. The variable alkaloid content based on growing conditions further complicates determining a universal “deadly dose,” emphasizing that any ingestion of an unknown nightshade plant should be considered serious.
Responding to Nightshade Exposure
Immediate action is necessary if nightshade ingestion is suspected. Do not induce vomiting, as this can cause further harm. Instead, contact a poison control center immediately or seek emergency medical attention. In the United States, the national toll-free Poison Help hotline can be reached by calling 1-800-222-1222.
When contacting medical professionals, provide as much detail as possible, including:
- The suspected plant
- The estimated amount ingested
- The time of ingestion
- Any symptoms observed
Treatment for nightshade poisoning often involves supportive care, such as administering activated charcoal to help absorb toxins and providing intravenous fluids. In some cases, an antidote like physostigmine may be used. Preventing exposure remains the most effective strategy. Educating children about the dangers of eating unknown plants and berries, wearing gloves when gardening near suspicious plants, and removing any toxic nightshade plants from yards can help reduce the risk of accidental poisoning.