A purple discoloration or bruising of your penis can happen for a number of reasons, here are some of the most common.
Arousal
When you’re sexually aroused blood flow to your penis increases, which can cause it to appear reddish or purplish. This is normal and nothing to worry about.
Trauma or injury
Rough sex, masturbation or injuries (like getting caught in a zipper or hit in the genitals) can rupture the blood vessels in your penis and cause bruising and a purple appearance. Severe trauma can cause a hematoma, which is when blood collects within the tissue and results in significant discolouration and swelling. A penis bruise caused by trauma will go away on its own.
Priapism
Bruising or change in colour of the penis can occur with priapism, a prolonged, often painful erection lasting more than four hours without sexual arousal. This can happen due to certain medications or drugs, an injury to the penis or groin, or medical conditions that affect blood flow, like sickle cell disease. If not treated quickly, priapism can cause permanent damage, leading to erectile dysfunction. Treatment usually involves draining the blood or, in some cases, surgery. If you notice these symptoms, don’t wait see a doctor immediately to prevent long-term problems.
Learn more about priapism and painful erections here.
Skin conditions
Some skin conditions that occur all over your body can also affect the penis. Lichen sclerosus can cause white patches and purple spots, and lichen planus can cause purple spots or sores with itching or pain. If you notice these symptoms see a doctor about it.
Allergic reaction
If you notice a rash, itching, or purple discolouration on your penis, it could be a sign of an allergic reaction or contact dermatitis — a skin irritation caused by soaps, detergents, or certain medications. Some chemicals or allergens can trigger inflammation, leading to redness, swelling and bruising-like discolouration. In some cases, scratching or continued irritation can make the skin more fragile, increasing the risk of small tears or bruising. If the symptoms don’t improve after stopping contact with the suspected irritant or if the reaction gets worse, see a doctor for advice — treatment may include antihistamines or steroid creams to reduce irritation and prevent further damage.
Sexually transmitted infections
If you notice purple sores, spots, or unusual discolouration on your penis, it could be a sign of a sexually transmitted infection (STI) like herpes or syphilis. Herpes can cause painful blisters that may scab over, while syphilis often starts with a painless sore that can later lead to a rash or skin changes. If left untreated, some STIs can lead to serious health issues, so it’s important to see a doctor for testing and treatment. Most STIs are manageable with medication, and early treatment helps prevent complications and reduces the risk of spreading the infection to a partner.
Purpura
If you notice small purple bumps or bruising on your penis that doesn’t seem to be from an injury, it could be a sign of purpura— a condition where tiny blood vessels leak under the skin due to an autoimmune reaction. Purpura can also cause symptoms like joint pain, swelling, or easy bruising in other parts of the body. While it’s not always serious, it can be linked to underlying health conditions that affect blood clotting or the immune system. If the discolouration doesn’t go away or you have other unusual symptoms, see a doctor to find out what’s causing it and get the right treatment.
Penile cancer
If you notice a persistent sore, lump, or unusual purple or red discolouration on your penis that doesn’t heal, it could be a sign of penile cancer. Other symptoms may include thickened skin, bleeding, or a smelly discharge under the foreskin. While penile cancer is rare, it’s more common in older men and those with long-term irritation, human papillomavirus (HPV) infection or poor genital hygiene. Early detection is key, as treatment is most effective in the early stages and may involve creams, surgery, or other medical procedures. If you have any unusual changes in the skin of your penis, see a doctor as soon as possible — most issues aren’t cancer, but it’s always best to get checked.
Learn more about penile cancer here.
Steven-Johnson syndrome
If you develop painful purplish blisters on your penis, along with sores on other parts of your body, it could be a sign of Stevens-Johnson Syndrome (SJS) — a rare but serious allergic reaction. SJS often starts with flu-like symptoms before causing severe skin reactions, including blistering, peeling, and open sores, which can be extremely painful and lead to infections. It’s usually triggered by certain medications, infections, or immune system reactions. SJS is a medical emergency and requires immediate treatment in a hospital to prevent serious complications. If you notice these symptoms, especially if they’re spreading or accompanied by fever, seek urgent medical help.
Penile melanosis
If you notice dark brown or black spots on your penis that aren’t raised or painful, it could be penile melanosis — a harmless skin condition caused by excess pigment in the skin. These spots are usually flat, irregular in shape, and may develop over time without any other symptoms. Unlike more serious conditions, penile melanosis doesn’t cause pain, itching, or bleeding, and it doesn’t increase the risk of cancer. However, if you notice changes in size, colour or texture, or if the spots start to bleed, it’s best to see a doctor to rule out other skin conditions.
If you notice any changes to your penis — purple colour or otherwise — that stick around for more than a few days, see your doctor.
