Thanks for your question. Some common reasons for having blood on your penis include:

• The skin on the penis has become irritated. This can be due to lots of things, including not having enough lubrication during masturbation.
  
• The urethra (tube that carries urine from your bladder to the tip of your penis) has become irritated. This can be due to irritating chemicals from certain lubricants or moisturizers getting into the urethra. If any objects are placed into the urethra this can cause damage to the urethra, and cause bleeding.
  
• Sexually transmitted infections. If you are having sex (vaginal, oral, or anal) with anyone else this can put you at risk for a sexually transmitted infections (STIs). Most people with STI’s have no symptoms. For people with male reproductive organs, symptoms can include blood in their urine, pus from their penis, and pain when they pee.
• Urinary tract infections. This is an infection of your urethra, bladder, or kidneys. This is more common in people who have female reproductive organs.

Ultimately, if you noticed blood once, the bleeding stopped, and you don’t have any other symptoms you can try taking a break from masturbating for a few days to let any irritation heal. Also check out our health guide on masturbation for other tips.If you keep noticing blood or have any other symptoms, it’s a good idea to see your health care provider. They can make sure there’s nothing more serious going on, such as an STI or urinary tract infection.