Several sexually transmitted infections can cause bumps in the genital area, but the most common culprits are HPV (genital warts), herpes, syphilis, and molluscum contagiosum. Each one produces a distinctly different type of bump, which can help you figure out what you might be dealing with before you get tested.
Genital Warts (HPV)
Human papillomavirus is the single most common STI associated with genital bumps. The warts it produces are small, skin-colored swellings that can appear alone or cluster together into a cauliflower-like shape. They’re usually painless and feel soft or slightly rough to the touch. Some genital warts are so small and flat they’re nearly invisible to the naked eye.
HPV warts have one of the longest and most unpredictable incubation periods of any STI. They can show up anywhere from three weeks to many months after exposure, which makes it difficult to pinpoint exactly when or from whom you contracted the virus. The warts themselves aren’t dangerous in most cases, but certain HPV strains (different from the ones causing visible warts) are linked to cancer risk over time.
Herpes (HSV)
Genital herpes causes fluid-filled blisters rather than solid bumps. Before the blisters appear, you’ll typically feel tingling, itching, or burning in the area for up to 48 hours. The first outbreak is usually the worst and can come with fever, headache, and swollen lymph nodes. After the blisters break open, they leave shallow sores that eventually crust over and heal.
Herpes blisters tend to appear quickly, with an average incubation period of about four days after exposure (ranging from 2 to 12 days). The key distinction from other STI bumps is the fluid inside and the painful, raw quality of the sores once they rupture. Herpes is a recurring infection, so outbreaks can return periodically, though they typically become milder over time.
Syphilis
Primary syphilis produces a single, firm, round sore called a chancre at the site where the bacteria entered your body. The chancre is typically 1 to 2 centimeters across with a raised, hardened edge. What makes it tricky is that it’s often completely painless, so people sometimes miss it entirely, especially if it forms inside the vagina or rectum.
The chancre usually shows up about three weeks after exposure, though the window ranges from 10 to 90 days. It heals on its own within 3 to 6 weeks, which can create a false sense of relief. Without treatment, the infection progresses to secondary syphilis, which can produce a different kind of bump: large, raised, grey-to-white lesions in warm, moist areas like the groin and mouth. These look nothing like the original sore and are highly contagious.
Molluscum Contagiosum
Molluscum produces some of the most recognizable bumps of any STI. The lesions are small (2 to 5 millimeters), flesh-colored, dome-shaped, and have a telltale dimple or pit in the center. They often look shiny or pearly. Unlike herpes or syphilis sores, molluscum bumps are painless and don’t ulcerate or crust over on their own.
Molluscum spreads through skin-to-skin contact, and its incubation period ranges from 2 weeks to 6 months. The bumps can persist for months if untreated but are generally considered a nuisance rather than a serious health threat. In people with weakened immune systems, particularly those with untreated HIV, the bumps can grow unusually large and widespread.
Less Common STI-Related Bumps
Gonorrhea can occasionally cause skin lesions that range from small raised spots to pustules, though this typically happens during disseminated infection when the bacteria has spread through the bloodstream. It’s far more common for gonorrhea to cause discharge and burning rather than visible bumps. Mpox produces painful lesions that progress through distinct stages: flat spots, raised bumps, fluid-filled blisters, pus-filled blisters, and finally crusted scabs. These lesions can appear on the genitals, around the anus, and on other parts of the body.
How to Tell STI Bumps From Normal Skin
Not every bump in the genital area is an STI. Several completely harmless conditions look similar enough to cause alarm.
Pearly penile papules are tiny, rounded or finger-like growths that line the ridge around the head of the penis, often in neat rows. They’re about 1 to 2 millimeters wide and can look white, yellow, or pink. They’re not contagious and aren’t caused by any infection. A healthcare provider can distinguish them from genital warts or molluscum using a magnifying instrument called a dermatoscope.
Ingrown hairs are another common mimic, especially after shaving. They tend to look like red, raised pimples and feel warm to the touch. The giveaway is usually a visible hair at the center of the bump. Herpes sores, by contrast, look more like an open scratch or raw area and don’t have a hair follicle at their core.
Fordyce spots are small, pale, raised dots that appear on the shaft of the penis or the labia. They’re simply visible oil glands and are completely normal.
Comparing STI Bumps at a Glance
- HPV warts: Soft, skin-colored, painless, sometimes cauliflower-shaped. Appear weeks to months after exposure.
- Herpes blisters: Fluid-filled, painful, preceded by tingling. Appear 2 to 12 days after exposure. Break open and crust over.
- Syphilis chancre: Single firm sore with raised edges, painless, heals on its own in weeks. Appears around 3 weeks after exposure.
- Molluscum: Small, dome-shaped, shiny, with a central dimple. Painless. Appear 2 weeks to 6 months after exposure.
The type of bump, whether it hurts, how many there are, and how quickly they appeared after potential exposure all point toward different infections. But visual identification alone isn’t reliable, even for experienced clinicians. Many of these conditions overlap in appearance, and some people carry infections with minimal or atypical symptoms. Testing is the only way to confirm what’s causing genital bumps, especially if you notice pain or burning when urinating, unusual discharge, itching, or bleeding from the bumps.