What could be causing black staining from urethra?

There are a few potential causes of black or brown-ish staining from the urethra. These can include:

* Medications: Certain medications, such as minocycline (used to treat acne) and rifampin (used to treat tuberculosis), can cause brown staining of urine, or even black urine in some cases.

* Kidney disease: In some people with advanced kidney disease, creatinine can start to build up in the body, which can result in black urine. This is known as azotemia.

* Trauma: An injury to the urethra can sometimes lead to bleeding, which can cause brown or black staining.

* Tumors or growths: Rarely, a tumor or other growth in the urethra can cause bleeding and black staining.

If you are experiencing black staining from the urethra, it's important to see your doctor to determine the cause and receive appropriate treatment. Your doctor can perform tests to check for any underlying medical conditions and recommend the best course of action based on your specific situation.