The mole under the nail is slightly painful.

Mild pain in a nail matrix nevus is usually caused by trauma, paronychia, or malignant transformation, and targeted treatment should be based on the specific cause. Detailed analysis is as follows:

1. Trauma

A nail matrix nevus is a pigmented nevus occurring in the nail matrix, which generally does not cause pain. However, if the area suffers compression or impact, local skin and tissue damage may occur, resulting in pain accompanied by redness and swelling. In such cases, proper care of the affected area is essential—minimizing irritation and friction can promote healing.

2. Paronychia

This condition is commonly associated with bacterial infection or trauma, leading to redness, swelling, and pain around the nail, which may also affect the area surrounding the nail matrix nevus and cause discomfort. Patients should follow medical advice and apply topical medications such as fusidic acid cream or mupirocin ointment for treatment.

3. Malignant Transformation

If a nail matrix nevus undergoes malignant transformation, localized pain often occurs, along with enlargement or widening of the nevus. In such cases, prompt medical attention and surgical intervention are necessary. In severe cases, chemotherapy or radiotherapy may be required under a doctor's guidance.

Patients with nail matrix nevi are advised to monitor symptoms regularly. Any abnormalities should be evaluated by a healthcare professional promptly to avoid delays in treatment. Maintaining emotional stability and avoiding excessive anxiety during treatment are also important.