Euphorbia

None well-documented

Euphorbia is a vast genus of flowering plants, with over 8,000 species globally, represented in Arizona landscapes by several distinct varieties with very different visual characters but one shared hazard: a white milky latex sap that is one of the most irritating plant substances encountered in residential garden settings.

The most commonly planted Arizona varieties include Pencil Cactus ( _E. tirucalli_), a fast-growing African native that reaches 25 feet and is prized for its dramatic sculptural form and red-orange winter coloring; Crown of Thorns ( _E. milii_), a thorny Madagascar shrub with small bright flowers popular in drought-tolerant borders; Gopher Spurge ( _E. rigida_), a blue-green ground cover used in mass plantings across Phoenix and Tucson; and Poinsettia ( _E. pulcherrima_), widely kept as a potted plant and grown outdoors in protected Phoenix and Tucson gardens. All produce the same milky latex when cut or damaged.

The allergy risk is entirely contact-based, not airborne. When Euphorbia latex contacts skin, it triggers irritant or allergic contact dermatitis, with redness, burning, blistering, and papulovesicular eruptions appearing 2 to 8 hours after exposure. Patch testing with fresh sap induced dermatitis at every tested site in a published PMC study. JAMA Pediatrics documented six pediatric cases requiring medical attention after casual contact during outdoor play. Eye exposure is the most serious risk: Euphorbia sap squirting or dripping into the eye causes immediate burning, corneal damage, and temporary vision loss that can last up to two weeks. BBC Gardeners World explicitly warns that eye protection is mandatory when handling the plant. Asthma from airborne latex particles has been documented in greenhouse workers exposed to poinsettia – relevant to florists, nursery workers, and anyone maintaining large collections indoors.

Always wear gloves, long sleeves, and safety glasses when pruning any Euphorbia species. Avoid touching eyes or face while handling, and wash hands and tools thoroughly with soap and water afterward. If sap contacts the eyes, flush immediately with clean water for at least 15 minutes and seek medical attention.