Flowers, while often symbols of beauty and affection, can sometimes cause discomfort or illness. The risks are specific to the plant species and the type of exposure. Understanding the distinct ways floral sources can impact human health—from immune responses to chemical poisoning—is the foundation for enjoying them safely.
Allergic Reactions from Floral Sources
The most common way flowers cause illness is through the immune system’s overreaction to specific compounds, primarily resulting in allergic symptoms. Airborne allergies, often referred to as hay fever, are triggered when pollen is suspended in the air and inhaled. High-pollen offenders often belong to the Asteraceae family, which includes daisies, sunflowers, chrysanthemums, and baby’s breath. These plants produce numerous pollen grains that cause classic symptoms such as sneezing, nasal congestion, and itchy, watery eyes.
Direct physical contact with certain flowers can trigger contact dermatitis, an inflammatory skin reaction. This is caused by irritating compounds within the plant’s sap or oils, rather than airborne pollen. For instance, handling daffodils can cause “daffodil itch,” as the plant’s mucilage contains alkaloids and calcium oxalate crystals that irritate the skin.
Similarly, florists frequently encounter “tulip fingers,” a rash caused by the allergen tulipalin A found in the tulip bulb and stem sap. The reaction is a delayed hypersensitivity, meaning the rash may appear hours or days after exposure. Chrysanthemums can also cause contact dermatitis due to compounds called sesquiterpene lactones.
Toxicity and Poisoning Risks
Beyond allergic responses, some flowers and plants contain chemical compounds that are inherently toxic if ingested. These toxins are often a defense mechanism developed by the plant to deter herbivores. Ingestion can cause effects ranging from mild gastrointestinal upset to life-threatening cardiac or neurological issues.
Oleander is among the most poisonous ornamental plants because all its parts contain potent cardiac glycosides, such as nerine and oleandrin. Ingesting even small amounts can rapidly affect the digestive, nervous, and cardiovascular systems, leading to severe symptoms like dizziness, vomiting, and irregular heart rhythms.
Similarly, the delicate Lily of the Valley contains cardiac glycosides that can be fatal if consumed, posing a significant danger to small children and pets. Daffodils, especially their bulbs, contain alkaloids that cause severe vomiting, abdominal pain, and diarrhea if accidentally eaten.
Hydrangea flowers and leaves contain cyanogenic glycosides, which can lead to symptoms like dizziness and convulsions. Because these plant toxins are not always neutralized by cooking or drying, any suspected ingestion requires immediate medical attention and contact with a poison control center.
Microbial Hazards Associated with Flowers
A less obvious source of illness involves the proliferation of microorganisms on the plant material and in the vase water. Fungi and mold growth thrive in the cool, damp environment of aging floral arrangements. This mold spreads through airborne spores and can cause respiratory issues, especially in individuals with pre-existing conditions like asthma or severe allergies.
The water in a vase quickly becomes a breeding ground for bacteria that originate from the cut stems, soil, and the surrounding environment. Within just a few days, the bacterial count in vase water can reach high levels. These microorganisms include species of Pseudomonas and Enterobacter, which are generally harmless to healthy individuals but can pose a concern.
For people who are immunocompromised, exposure to these waterborne bacteria can represent an opportunistic infection risk. The presence of high bacterial loads can also cause the flower stems to block, leading to premature wilting. While the primary risk of these microbes is to the lifespan of the flowers, their presence highlights the need for basic hygiene when handling arrangements.
Safe Handling and Prevention
Preventing sickness requires an approach that addresses all three categories of risk: allergy, toxicity, and microbes. For individuals with known pollen allergies, it is helpful to opt for low-pollen alternatives like roses, orchids, or tulips, which typically have heavy, sticky pollen less likely to become airborne. If high-pollen flowers are present, lightly misting them with water can help weigh down the pollen and reduce its spread.
To avoid contact dermatitis, wear gloves when handling plant parts known to contain irritating sap, such as daffodils, tulips, or chrysanthemums. After handling any plant material, thoroughly washing hands with soap and water is an effective step to remove irritating oils and sap.
To mitigate poisoning and microbial risks, toxic flowers must be kept out of the reach of children and household pets, who are the most frequent victims of accidental ingestion. For cut flowers, changing the vase water daily or using a commercial flower food containing an antimicrobial agent will reduce the proliferation of bacteria and mold. Disposing of wilted or old arrangements promptly also prevents the buildup of fungal spores and stagnant water.