Penis Lumps, Spots or Sores: Causes & Advice, Wimbledon GP

Noticing a lump, white spot, blister or sore on your penis can be worrying, particularly if your first thought is a sexually transmitted infection. I'm Dr Umer Malik, a GP at Mayfield Clinic Wimbledon, and this is one of the questions I'm asked most often in clinic. The honest answer is that not every change to the skin of the penis is a sign of infection. Some are harmless variations in normal skin. Others are caused by inflammation, skin conditions, or infections such as genital herpes, genital warts and syphilis. Occasionally, a change needs further investigation. Here, I explain what can cause these symptoms, how we investigate them, and when it's time to seek medical advice.

What causes lumps, spots or sores on the penis?

There are several possible causes, and their appearance can give clues, although it isn't always possible to identify the cause by looking alone. In my experience, this is where a lot of unnecessary worry comes from. People search online, compare photographs, and often reach the wrong conclusion.

Common possibilities I see include:

Pearly penile papules, which are small, smooth, skin-coloured or whitish bumps, usually arranged in one or more rows around the rim of the head of the penis. They are harmless, are not sexually transmitted, and are often mistaken for genital warts.

Fordyce spots, small, pale or yellowish spots caused by visible oil glands. These are harmless and do not need treatment.

Balanitis, which is inflammation of the head of the penis. It can cause redness, swelling, itching, soreness or discharge. Causes include irritation, skin conditions and infections, including thrush. Repeated thrush on the penis can be a sign of diabetes, so a urine or blood sugar test may be worthwhile.

Genital herpes, an STI caused by herpes simplex virus. It can cause small blisters that break down into painful sores, sometimes with tingling, itching or pain when passing urine.

Genital warts, growths caused by certain types of human papillomavirus (HPV), which may appear as small, fleshy bumps or clusters of growths.

Syphilis, an STI that can cause an ulcer, often painless, although its appearance can vary.

Molluscum contagiosum, small, firm, pearly bumps with a dimple in the centre, caused by a common skin virus.

Lichen sclerosus, white, shiny or tight patches of skin, sometimes making the foreskin hard to pull back. This needs treatment and follow-up, as it slightly increases the risk of penile cancer.

Other skin conditions, including irritation, friction, eczema, psoriasis and lichen planus, can also cause changes to the skin of the penis.

Occasionally, a persistent lump, ulcer or other skin change can be a sign of a more serious condition, including penile cancer, which is rare. Because so many of these conditions can look similar, I'd always caution against assuming a sore is herpes or another STI based on appearance alone. A clinical assessment can establish what's actually going on.

Can HSV-1 cause genital herpes, and what does it look like?

Yes. Herpes simplex virus type 1 (HSV-1) can cause genital herpes, as can herpes simplex virus type 2 (HSV-2). HSV-1 is best known for causing cold sores around the mouth, but it can also infect the genital area. Genital HSV-1 is often passed on through oral sex, including from a partner who has oral herpes.

Symptoms can include small blisters that break open and leave shallow sores or ulcers, pain, tenderness or burning around the affected area, tingling or itching before blisters appear, pain when passing urine, particularly if urine touches the sores, and swollen glands or flu-like symptoms during a first episode.

Not everyone develops the typical clusters of blisters. Herpes can appear as a single ulcer, a small split in the skin, or an area of irritation, which can make it hard to tell apart from other conditions. The first noticeable outbreak can occur days, weeks, months or even years after the infection was caught. Some people have very mild symptoms or never realise they have it.

If you have a new genital blister or ulcer, I'd recommend getting it assessed promptly while it is still present. Swabs are most reliable in the first few days, before sores crust over or heal. For a first episode, antiviral treatment works best when started early, ideally within five days, so don't wait to see if it settles.

How does a GP tell whether a sore is herpes or something else?

The first step is always a clinical assessment. I'll ask about your symptoms, when the lesion appeared, whether it's painful or itchy, whether you've had similar episodes before, and whether there has been any recent sexual contact that could be relevant. With your consent, I may examine the area, which can help identify features that point to a particular diagnosis, although appearance alone may not give a definite answer.

Depending on the findings, investigations may include a swab from the sore. A sample from a blister or ulcer can be tested for herpes simplex virus using a molecular test such as PCR. A single swab can usually be tested for both herpes and syphilis, with results typically within a week. Sampling a fresh, active sore gives the most reliable result.

Blood tests for syphilis and other infections may also be recommended, depending on the appearance of the sore and your sexual history. Other STI tests, including for HIV, might be appropriate depending on your circumstances. If the diagnosis remains uncertain, the sore doesn't heal, or there are features of a non-infectious skin condition, further assessment or referral may be needed.

It's worth knowing that a herpes blood test isn't usually the best way to find the cause of a new, visible genital sore when a swab can be taken. Blood tests and swabs answer different questions. A home STI test can be useful in some situations, but it cannot replace an examination when you have an unexplained lump, blister or ulcer. Different conditions need different tests, and some can only be identified by looking at them. If you'd like to discuss testing options, our sexual health service at Wimbledon can help.

Does a herpes or genital wart diagnosis mean a partner has been unfaithful?

This is a question I hear often, and the answer is no. A diagnosis of genital herpes does not, by itself, show when the infection was caught or who it came from. Herpes simplex virus can stay in the body without causing noticeable symptoms, so someone may have caught it long before their first recognised outbreak. HSV-1 can also cause genital herpes after oral sex with a partner who has oral herpes, and oral herpes can be passed on even when there's no visible cold sore.

The same applies to genital warts. HPV, the virus that causes them, can stay in the skin for months or years before a wart appears, and most sexually active people are exposed to it at some point. If you or your partner has been diagnosed with genital herpes or warts, a healthcare professional can explain how it's passed on, how to reduce the risk of passing it on, and whether any testing is needed. It's understandable to feel anxious or embarrassed about a possible STI, but these symptoms are a reason to seek medical advice, not to make assumptions about how or when an infection was caught.

When should you see a GP?

Arrange a medical assessment if you notice a new or unexplained lump, spot, blister, ulcer, rash or other change to the skin of your penis. You should also seek advice if the head of your penis becomes swollen, red, itchy or sore, or if you have unusual discharge or pain when passing urine.

Seek prompt assessment for a new genital ulcer or blister. Testing for herpes works best while the sore is still present, and early treatment works best. Don't wait for a sore to become painful before seeking advice. Some conditions, including syphilis, can cause painless ulcers.

A growth or sore that hasn't healed within four weeks needs medical assessment, as do persistent skin changes, unexplained bleeding or a change in the foreskin. These symptoms don't necessarily mean cancer, but they shouldn't be ignored.

While you wait to be seen, avoid squeezing, picking or applying creams that haven't been prescribed. Avoid sexual contact if you have a new blister, ulcer or suspected herpes until you've been assessed. And try not to diagnose the lesion yourself from online photographs, as this can cause unnecessary worry or false reassurance.

At Mayfield Clinic Wimbledon, you can book a GP appointment to discuss an unexplained lump, spot, blister or sore on your penis. We can assess your symptoms and arrange appropriate tests, treatment or referral through our general practice service. Depending on the findings, an NHS sexual health clinic may sometimes be the most appropriate service, and we'll tell you if that's the case.

This article provides general information and is not a substitute for individual medical advice. Lumps, spots and sores on the penis can have several causes, and diagnosis may need an examination and appropriate tests.

Dr Umer Malik MBBS, BSc, MRCGP, MPH has 17 years of postgraduate clinical experience as a doctor, including nine years as a fully qualified GP. He sees patients at Mayfield Clinic Wimbledon.

If you're concerned about a change to the skin of your penis, book a GP appointment at Mayfield Clinic Wimbledon.