From the Guidelines
Darkening of the nails can be caused by various conditions, including fungal infections, trauma, and bacterial infections, with Pseudomonas aeruginosa potentially resulting in green or black discoloration of the nails.
Causes of Nail Darkening
Some of the key causes of nail darkening include:
- Fungal infections, such as onychomycosis, which can cause yellow or brown discoloration as fungi grow beneath the nail 1
- Bacterial infections, particularly those caused by Pseudomonas aeruginosa, which can lead to green or black discoloration of the nails 1
- Trauma to the nail plate, which can result in subungual hematomas, appearing as dark purple or black spots
- Systemic conditions, such as melanoma, psoriasis, and endocrine disorders, which can also cause nail darkening
- Certain medications and smoking, which can stain nails yellow-brown due to nicotine exposure
Diagnosis and Treatment
It is essential to evaluate the underlying cause of nail darkening to provide appropriate treatment, ranging from antifungal medications for infections to discontinuing causative medications when possible 1. If nail darkening occurs suddenly, spreads to multiple nails, or is accompanied by pain or nail deformity, medical evaluation is recommended to rule out serious conditions like melanoma. In some cases, nail darkening can be a symptom of an underlying condition, such as Candida nail infection, which can cause white, green, or black marks to appear on the nail plate 1.
Key Considerations
When diagnosing and treating nail darkening, it is crucial to consider the potential causes and underlying conditions, as well as the patient's medical history and symptoms. By evaluating the underlying cause of nail darkening, healthcare providers can provide effective treatment and prevent potential complications. In cases where the cause of nail darkening is unclear, further evaluation and testing may be necessary to determine the underlying condition and provide appropriate treatment.
From the Research
Causes of Darkening of Nails
- Fungal infections, such as onychomycosis, can cause darkening of the nails 2, 3
- Onychomycosis is a common fungal infection of the nail unit, and approximately 90% of toenail and 75% of fingernail onychomycosis are caused by dermatophytes 2
- Clinical manifestations of onychomycosis include discoloration of the nail, subungual hyperkeratosis, onycholysis, and onychauxis 2
Risk Factors for Darkening of Nails
- Certain high-risk populations, such as the immunocompromised, diabetics, and human immunodeficiency virus (HIV)-positive patients, are more prone to developing onychomycosis and subsequent darkening of the nails 4
- Nondermatophyte fungi can also cause onychomycosis and darkening of the nails, and can be difficult to treat 4
Treatment Options for Darkening of Nails
- Oral antifungal therapies, such as terbinafine, are effective in treating onychomycosis and darkening of the nails, but can have significant adverse effects 2, 3, 5, 6
- Topical antifungal therapies can be considered for mild to moderate onychomycosis and are a therapeutic option when oral antifungal agents are contraindicated or cannot be tolerated 2, 3