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Published on: 8/20/2026
Why is there a green spot under my nail and should I be concerned?
A green spot under your nail is most often a sign of green nail syndrome (chloronychia), a bacterial infection typically caused by Pseudomonas aeruginosa. The bacteria thrive in moist environments, producing a pigment that stains the nail green, blue-green, or black. Common causes include prolonged water exposure, nail trauma, or lifting of the nail plate (onycholysis).
While green nail syndrome is usually not serious, it won't resolve on its own and can worsen without proper care. Treatment may involve topical or oral antibiotics, keeping the nail dry, and trimming the affected area.
Because nail discoloration can also signal other conditions—such as fungal infections, melanoma, or trauma—it's important to identify the cause quickly. Taking a free, instant, online symptom check can help you understand what's likely behind the green spot, how urgent it is, and what next steps to take before seeing a doctor.
Reviewed for medical accuracy: 07/15/2026
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Explanation
A green spot under your nail might be caused by a condition known as green nail syndrome. This condition is often due to bacteria that can get under the nail, especially if it has been damaged or exposed to water a lot.
Here are some important points to consider:
- Cause: The green color is usually because of bacteria, which can happen if your nail or the skin around it is damaged.
- Risk Factors: People who have their hands in water a lot or have nails that are often injured are more likely to get this.
- Recommendation: It is a good idea to see a doctor. They can help figure out what is causing the green spot and how best to treat it. You can start by taking a free symptom checker assessment to better understand your condition before your appointment.
Taking care of your nails and keeping them dry and clean can help prevent this condition. If you notice any changes in your nails, it's always a good idea to talk to a healthcare provider.
(References)
Ghosh SK, & Bandyopadhyay D. (2019). green diseases of the skin, nails, and mucosa. Clinics in dermatology, 31896406.
Sánchez AR, Rogers RS 3rd, & Sheridan PJ. (2004). Tetracycline and other tetracycline-derivative staining .... International journal of dermatology, 15485524.
(2014). Drug-induced nail disorders. Prescrire international, 25162091.
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