A sudden green discoloration on a fingernail or toenail, medically known as chloronychia, is usually a sign of an underlying bacterial infection. This infection thrives in moist conditions beneath the nail plate. Understanding the cause allows for targeted treatment and effective prevention.
The Main Culprit: Green Nail Syndrome
Green Nail Syndrome is caused by the bacterium Pseudomonas aeruginosa. This common, opportunistic organism is found ubiquitously in water and soil. It only becomes problematic when the nail unit provides a suitable, moist environment for colonization.
The bacterium produces two pigments: pyocyanin (blue-green) and pyoverdin (yellowish-green). These pigments diffuse into the soft tissue beneath the nail plate, resulting in discoloration that ranges from light green to dark green. Since the pigment is produced by multiplying bacteria, it cannot be washed away or scrubbed off.
The primary predisposing factor is onycholysis, the separation of the nail plate from the nail bed. This separation creates a damp pocket where Pseudomonas aeruginosa can flourish. This is common in individuals frequently exposed to water, soaps, or detergents, such as healthcare workers. Artificial nails are another frequent contributor due to moisture trapped beneath the extension.
Differentiating Infection from External Stains
Identifying the source of the green color is crucial, as not all discolorations are infectious. Green Nail Syndrome discoloration is located under the nail plate, infused into the nail bed. This location ensures the color remains fixed even after cleaning.
External stains from sources like dyes or cleaning products are usually superficial and located on the surface of the nail plate. These stains might be faded or removed by scrubbing. Other conditions, such as a subungual hematoma or melanoma, cause dark discoloration, but these are typically black, brown, or blue, not green.
A bacterial infection is often accompanied by onycholysis, where the nail appears lifted from the skin underneath. If the green area is confined to a small spot and is not associated with nail separation, an external stain is more likely. Any persistent discoloration warrants closer attention.
Treatment Options and Medical Consultation
Treatment focuses on eliminating the bacteria and creating a dry environment to prevent reinfection. For mild cases, home care involves keeping the affected nail dry and minimizing water exposure using protective gloves for wet tasks. Applying a diluted acetic acid solution (white vinegar mixed with water in a 1:4 ratio) as a soak for 10 minutes two to three times daily can help create an unfavorable environment.
If the discoloration is extensive, spreading, or if home treatments fail within a few weeks, consult a medical professional. A dermatologist may prescribe topical antibiotic solutions, such as ciprofloxacin drops, applied directly to the affected nail bed. These treatments target the bacterial colonies beneath the nail plate.
In severe or chronic instances, oral antibiotics may be necessary. If onycholysis is extensive, the detached portion of the nail may need to be trimmed or partially removed. This allows topical medication to reach the infection source and ensures complete drying. Treatment of concurrent conditions, such as nail psoriasis or a fungal infection, is also necessary to resolve the environment that permits Pseudomonas colonization.