Most sexually transmitted infections fall into a few visual categories: blisters, sores, warts, rashes, unusual discharge, or tiny bumps. But here’s the critical thing to know upfront: roughly two-thirds of STI cases produce no visible symptoms at all. In one clinical study, 72.5% of chlamydia infections and 70% of gonorrhea infections were completely asymptomatic. So while knowing what STDs can look like is useful, the absence of symptoms never means the absence of infection.
With more than 2.2 million reported cases of chlamydia, gonorrhea, and syphilis in the U.S. in 2024 alone, these infections are common. Here’s what each one actually looks like when it does show up on your body.
Herpes: Fluid-Filled Blisters That Crust Over
Herpes (HSV-1 or HSV-2) is the STD most people picture when they think of visible symptoms. It causes small, fluid-filled blisters that eventually break open and crust over. Before blisters appear, the skin typically tingles, itches, or burns for up to 48 hours. You might also develop a fever, headache, or swollen lymph nodes during that window.
The blisters can show up on the genitals, buttocks, thighs, or around the mouth. Once they break, they leave shallow, reddish open sores that look more like a scrape or raw patch than a pimple. The first outbreak is usually the worst and can take two to four weeks to heal. Later outbreaks tend to be milder and shorter. Symptoms first appear an average of four days after exposure, though the range is 2 to 12 days. Some people never notice their symptoms because they’re too mild to register.
Syphilis: A Painless Sore, Then a Body Rash
Syphilis moves through distinct stages, each with a different look. In the primary stage, a single painless sore called a chancre appears at the spot where the infection entered your body, usually the genitals or mouth. It shows up anywhere from 10 to 90 days after exposure, with 21 days being the average. The chancre is firm and round, and because it doesn’t hurt, it’s easy to miss entirely. It heals on its own within a few weeks, which tricks many people into thinking the problem is gone.
It’s not. In the secondary stage, a rash develops that’s pink or dusky red, often with a slightly scaly texture and firm, raised skin. The hallmark of secondary syphilis is that the rash appears on the palms of the hands and soles of the feet, locations where most other rashes don’t show up. It can also spread across the torso, arms, and legs. Without treatment, syphilis continues to progress internally even after visible symptoms disappear again.
Genital Warts: Fleshy Growths in Various Shapes
Genital warts, caused by certain strains of HPV, are among the most visually variable STDs. They can be flat, dome-shaped, or have a bumpy, cauliflower-like texture. Colors range from white to pink, purple, red, or brown. Some are so small and flat they’re nearly invisible, while others grow into larger clusters. They can appear on the vulva, penis, scrotum, anus, or upper thighs.
Warts typically show up weeks to months after exposure, sometimes longer. There’s no screening test for genital warts. They’re diagnosed by visual inspection. HPV itself is extremely common and often clears on its own, but the wart-causing strains can persist and recur.
Molluscum Contagiosum: Small Bumps With a Dimple
Molluscum contagiosum causes small, firm, raised bumps that are usually white, pink, or skin-colored. They range from the size of a pinhead to the size of a pencil eraser. The defining feature is a small dip or dimple in the center of each bump, which gives them a distinctive look compared to pimples or other skin bumps. They can appear almost anywhere on the body, though they rarely show up on palms or soles.
The incubation period ranges from two weeks to six months. There’s no screening blood test for molluscum. Like genital warts, it’s diagnosed visually.
Discharge Changes From Chlamydia, Gonorrhea, and Trichomoniasis
Some of the most common STDs don’t produce sores or bumps at all. Instead, they change the color, consistency, or smell of genital discharge.
- Chlamydia and gonorrhea can cause cloudy, yellow, or green discharge. Gonorrhea symptoms, when they appear, usually show up within 2 to 8 days. Chlamydia typically takes 1 to 3 weeks. But the majority of infections with either one produce no noticeable symptoms, especially vaginal infections.
- Trichomoniasis causes discharge that’s green, yellow, or gray and often bubbly or frothy. Symptoms develop within 5 to 28 days of exposure.
In people with a penis, these infections more commonly cause burning during urination or a discharge from the urethra. In people with a vagina, the infections are more likely to be silent, which is why routine screening matters even without symptoms.
Scabies and Pubic Lice: Itching With Visible Tracks or Nits
Scabies causes intense itching and tiny raised lines on the skin called burrows. These are grayish-white or skin-colored, crooked, and just beneath the skin surface. They can be hard to spot because an infected person typically has only 10 to 15 mites on their entire body. The itching tends to be worse at night and affects the folds of skin between fingers, wrists, elbows, and the genital area.
Pubic lice (crabs) cause itching in the groin area. You may see tiny lice or their eggs (nits) attached to pubic hair. Symptoms begin 2 days to 2 weeks after exposure. Neither scabies nor pubic lice has a screening test; both are diagnosed by looking at the skin.
How to Tell an STD From a Pimple or Ingrown Hair
Genital bumps cause a lot of anxiety, and many turn out to be completely harmless. An ingrown hair is usually a single reddened, raised bump that’s warm to the touch and looks like a pimple. You can often see a hair trapped at the center. It stays in one spot and resolves within a few days.
Herpes blisters, by contrast, tend to appear in clusters rather than as a single bump. They look more like raw, open areas than pimples, and they can show up anywhere on your body rather than staying localized to one hair follicle. Herpes outbreaks also come with systemic symptoms like fatigue, fever, and swollen lymph nodes, which ingrown hairs never cause.
Fordyce spots are another common source of worry. These are tiny, pale, slightly raised dots on the shaft of the penis or the labia. They’re completely normal oil glands visible through thin skin, not an infection.
When Symptoms Don’t Show Up at All
The most important visual sign of an STD is often no sign at all. Chlamydia, gonorrhea, HIV, hepatitis B, hepatitis C, and even syphilis can all be present without producing anything you can see or feel. HIV, for instance, sometimes causes mild body aches and fever within one to two weeks of exposure, then can go months to years without symptoms. Hepatitis B and C often produce no symptoms for weeks or months, sometimes much longer.
Testing windows vary by infection. Chlamydia and gonorrhea tests are reliable about one to two weeks after exposure. Syphilis blood tests catch most infections at one month, nearly all by three months. HIV blood tests using modern methods detect most cases by two weeks, with six weeks catching almost all. Herpes antibody tests need about four months to be fully reliable. If you’re concerned about a possible exposure, the timing of your test matters as much as getting one.