Foxglove (Digitalis purpurea) is a strikingly beautiful plant often cultivated in gardens for its tall, colorful, bell-shaped flowers, which typically range from pink and purple to white hues. The plant is native to the British Isles and Western Europe, and its compounds were first documented for therapeutic effects in the 18th century. Despite its ornamental appeal, foxglove is extremely toxic, containing powerful substances that can severely affect the heart. All parts of the plant, including the leaves, stems, flowers, and seeds, contain these poisonous compounds. The danger of this plant lies primarily in accidental ingestion, but exposure through other routes also warrants caution.
Dermal Contact: Risk of Touching Foxglove
While the foxglove plant is highly toxic when eaten, the risk of serious systemic poisoning simply from touching it is generally low for people with intact skin. The primary danger is not that the toxins will be absorbed across the skin in sufficient amounts to cause cardiac problems. However, contact with the sap can cause localized reactions, such as irritation, redness, or a rash.
The more significant risk associated with handling the plant stems from the possibility of transferring residue to sensitive areas of the body. Rubbing the eyes or touching the mouth after handling foxglove without washing hands can easily introduce the compounds into the body’s systems. Furthermore, if the plant material comes into contact with broken skin, the risk of absorption increases. Individuals who work extensively with the plant may experience symptoms from prolonged exposure if they are not wearing appropriate protective gear.
The Toxic Compounds in Foxglove
The toxic properties of foxglove are attributed to a group of compounds known as cardiac glycosides. The two most prominent and medically relevant compounds found in the plant are digitoxin and digoxin. These substances are potent and have been purified for use in prescription medicines for treating certain heart conditions.
The mechanism of toxicity involves the interference of these glycosides with a structure found in muscle cells called the sodium-potassium ATPase pump. This pump is fundamental for maintaining the electrical potential necessary for normal cell function. Cardiac glycosides block the activity of this pump, which causes the concentration of sodium ions inside the cell to increase.
This rise in intracellular sodium subsequently affects a different exchanger, the sodium-calcium exchanger, leading to an accumulation of calcium ions inside the heart muscle cells. The resulting increase in intracellular calcium enhances the force of heart contractions. At toxic levels, this interference with the heart’s electrical system overwhelms the cardiac tissue, causing dangerous arrhythmias and conduction blocks.
Symptoms of Systemic Poisoning
Systemic poisoning from foxglove occurs when any part of the plant is consumed. Symptoms of intoxication typically fall into three categories: gastrointestinal, cardiac, and neurological. The first signs often include gastrointestinal issues, with the rapid onset of nausea, vomiting, diarrhea, abdominal pain, and a loss of appetite.
Cardiac symptoms are the most serious and directly result from the toxin’s effect on the heart muscle. These can manifest as an irregular heartbeat, a dangerously slow pulse (bradycardia), or various forms of heart block. In severe cases, the heart’s electrical instability can lead to life-threatening conditions like ventricular fibrillation or asystole. Low blood pressure and collapse are also possible signs of severe cardiac toxicity.
Neurological and visual disturbances provide another set of characteristic symptoms. These can include headache, lethargy, weakness, and confusion or disorientation. A unique symptom of foxglove poisoning is a change in vision, specifically seeing halos of color, often described as yellow or green, around objects.
Safe Handling and Emergency Response
Managing foxglove safely involves preventative measures to avoid both dermal contact and accidental ingestion. When handling the plant, wearing impermeable gloves is recommended to prevent skin irritation and the transfer of sap. After handling foxglove, wash hands thoroughly with soap and water before touching the face, eating, or drinking.
Foxglove should not be planted in areas where children or pets play, as the entire plant is toxic. If the plant must be removed, long sleeves, long pants, and eye protection should be worn, especially when using methods like mowing or brush-cutting that can aerosolize plant particles. The plant material should never be burned, as the smoke can be poisonous, nor should it be added to compost.
If ingestion of any part of the foxglove plant is suspected, immediate action is necessary. The local Poison Control Center should be contacted right away by calling the national toll-free Poison Help hotline. It is helpful to provide information about the person’s age, weight, and general condition, along with the amount of plant material believed to have been swallowed and the time of ingestion. Do not attempt to induce vomiting unless specifically instructed to do so by a healthcare professional.