Japanese honeysuckle (Lonicera japonica) is a vigorous, fast-growing vine native to East Asia. It is widely recognized for its sweet, pervasive fragrance and is often found growing in landscapes and wild areas. While the plant is not considered deadly, it contains compounds that render it mildly toxic, particularly when consumed in large quantities. The greatest risk is associated with ingesting the small, dark berries produced later in the growing season.
Identifying Japanese Honeysuckle
Identifying Lonicera japonica accurately is the first step in managing exposure risk. The plant is a twining, woody vine that grows aggressively, often climbing over other vegetation or acting as a groundcover. Its leaves are arranged oppositely along the stem and are typically oval or oblong with smooth edges.
The most distinctive feature is the tubular flower, which appears in pairs from late spring into fall. These flowers start creamy white and gradually age to pale or golden yellow, emitting a strong, sweet scent. Following the bloom, the plant produces small, spherical fruits that are initially green and mature to a shiny, dark blue-black color.
This dark fruit, a berry roughly 6 millimeters in diameter, poses the most significant ingestion risk due to its noticeable appearance. The vine’s ability to quickly spread and form dense mats increases the likelihood of human or animal contact.
Specific Toxic Components and Plant Parts
The toxicity of Japanese honeysuckle stems from naturally occurring chemical compounds. The primary culprits are saponins, which are detergent-like substances found in many plants. These saponins cause irritation and inflammation in the gastrointestinal tract upon consumption.
While the entire plant can be toxic, the highest concentration of these compounds is found within the small, black berries. The leaves and stems also contain saponins, along with smaller amounts of cyanogenic glycosides and alkaloids.
The fragrant flowers, often used in traditional herbal medicine, are generally not considered toxic. The sweet nectar within the tubular blossoms is usually safe to consume in small quantities. The potential for poisoning is directly related to the part of the plant and the quantity ingested.
Symptoms Following Ingestion
The symptoms following ingestion are primarily digestive, resulting from the irritating saponins. In both humans and pets, the most common effects include mild gastrointestinal distress, manifesting as nausea, vomiting, diarrhea, and sometimes abdominal pain.
For humans, especially children, symptoms are usually limited to digestive upset if only a few berries are eaten. However, consuming a large number of berries can lead to more concerning signs, such as an elevated heart rate, dilated pupils, and cold sweats. Severe systemic effects, including respiratory failure or convulsions, are extremely rare and associated with massive ingestion.
Pets, particularly dogs and cats, can exhibit similar but sometimes more pronounced digestive upset due to their smaller body mass. In addition to vomiting and diarrhea, pet owners may notice lethargy, excessive drooling, or a loss of appetite. Since animals may ingest more of the plant material, monitor them closely for any signs of physical distress. Any severe or persistent symptoms warrant immediate attention from a medical professional.
Immediate Steps After Exposure
If you suspect a person has ingested any part of the plant, immediate action is necessary. Do not wait for symptoms to develop before seeking professional advice; immediately contact the national Poison Control Center, available 24/7.
If the exposure involves a pet, contact a veterinarian or a pet-specific poison control hotline right away. When calling, provide details including the part of the plant consumed and the estimated quantity. While awaiting guidance, gently rinse the mouth of the affected individual or pet with water to remove residual plant material. Follow all instructions provided by the medical professional.