Most STDs fall into a few visual categories: sores or ulcers, bumps or warts, unusual discharge, or rashes. Some cause no visible signs at all. Knowing what each one looks like helps you recognize something early, but it also helps you understand why you can’t always tell by looking. Roughly 70% of chlamydia cases in women and 70% of herpes cases produce zero symptoms.
Herpes: Blisters That Break Open
Genital herpes typically starts with tingling, itching, or burning in one spot, lasting up to 24 hours before anything visible appears. Then a patch of red, swollen skin develops on the genitals, anus, thighs, or buttocks. Small fluid-filled blisters form on that patch, break open into shallow, painful sores, then scab over and heal within two to six weeks. The first outbreak is usually the worst. Later outbreaks tend to be milder and shorter, and many people learn to recognize the warning tingling before sores appear.
Herpes sores can also show up around or inside the mouth (cold sores from oral sex transmission). They look like small red bumps that turn into open ulcers. One common source of confusion: herpes blisters can resemble ingrown hairs or pimples. The difference is that ingrown hairs usually have a visible hair at the center and look like a raised pimple, while herpes sores tend to look more like a scratch or raw, open area. Herpes sores also cluster together, while ingrown hairs are usually solitary.
Symptoms can appear as early as two days after exposure, with an average of about four days.
Syphilis: A Painless Sore, Then a Rash
Syphilis has distinct stages, and each one looks different. The first stage produces a single small sore called a chancre, usually on the genitals, rectum, tongue, or lips. The defining feature of this sore is that it’s painless, firm, and round. Many people never notice it at all because it doesn’t hurt. It appears anywhere from 10 to 90 days after exposure (average around three weeks) and heals on its own, which can create a false sense that nothing is wrong.
If untreated, syphilis moves to its secondary stage. This is when a rash appears, and it has a signature pattern: rough, reddish-brown spots on the palms of the hands and soles of the feet. Most rashes from other conditions don’t show up in these locations, so palm and sole involvement is a strong clue. The rash can also spread across the trunk and other parts of the body, sometimes accompanied by a sore throat or swollen glands.
Genital Warts: Flesh-Colored Growths
HPV causes genital warts that look quite different from herpes or syphilis. They’re flesh-colored or slightly darker growths that can be flat, raised, or have a bumpy, cauliflower-like texture. They appear on the genitals, around the anus, and rarely in the mouth or throat after oral sex. They’re usually painless and may show up as a single bump or in clusters.
Warts can take weeks to many months to appear after exposure, which makes it hard to trace them back to a specific contact. They grow outward from the skin’s surface rather than forming open sores, which visually sets them apart from herpes or syphilis.
Molluscum Contagiosum: Dimpled Bumps
Molluscum produces raised, round, skin-colored bumps with a telltale small dent or dimple at the top center. That central dimple is the key identifier. The bumps are smooth, firm, and painless. When spread through sexual contact, they typically appear on the genitals, inner thighs, or lower abdomen. They can show up anywhere from two weeks to six months after exposure and may persist for months if untreated.
Discharge-Based STDs: Chlamydia, Gonorrhea, Trichomoniasis
Some STDs don’t produce visible sores or bumps. Instead, they cause abnormal discharge. Chlamydia, gonorrhea, and trichomoniasis can all produce yellow-green discharge, making them hard to distinguish from each other on appearance alone. In men, gonorrhea often causes a noticeable discharge from the penis and burning during urination, sometimes within two to eight days of exposure. Chlamydia can cause similar discharge but is more likely to be silent: about 50% of men and 70% of women with chlamydia have no symptoms at all.
Trichomoniasis may cause frothy or foul-smelling discharge in women along with genital itching and irritation. Symptoms typically develop within five to 28 days. In men, trichomoniasis rarely causes visible symptoms. Gonorrhea is also frequently silent in women, with at least 50% of cases producing no noticeable signs.
Oral STD Symptoms
STDs don’t only affect the genitals. Syphilis chancres can form on the tongue or lips, looking the same as they do elsewhere: painless, firm, round sores. Gonorrhea in the throat causes soreness and swollen neck glands but usually no visible sores. Herpes around the mouth produces the same blister-to-ulcer pattern seen on the genitals. HPV can, in rare cases, cause warts inside the mouth or throat.
Early HIV infection sometimes causes mouth ulcers and a sore throat alongside flu-like symptoms such as body aches and fever, typically one to two weeks after exposure. In its advanced stage, HIV can produce sores in the mouth and discolored blotches on or under the skin.
How Quickly Symptoms Appear
The gap between exposure and visible signs varies widely by infection:
- Herpes: 2 to 12 days, average 4 days
- Gonorrhea: usually 2 to 8 days, up to 2 weeks
- Chlamydia: 1 to 3 weeks
- Syphilis: 10 to 90 days, average 21 days
- Trichomoniasis: 5 to 28 days
- Genital warts (HPV): 3 weeks to many months
- Molluscum contagiosum: 2 weeks to 6 months
- Hepatitis B: usually 6 weeks, up to 6 months
- HIV: mild flu-like symptoms in 1 to 2 weeks, then potentially months to years before further signs
Why You Can’t Always See an STD
The most important thing about what STDs look like is that many of them look like nothing. About 70% of people with herpes never develop recognizable symptoms. Up to 40% of men and at least 50% of women with gonorrhea show no signs. Half of men and 70% of women with chlamydia have no symptoms whatsoever. A syphilis chancre can appear inside the rectum or on the cervix where it’s impossible to spot visually.
This is why visual checks, whether of yourself or a partner, are not a reliable way to screen for infections. Many STDs are diagnosed only through testing, and some of the most common ones are the most likely to be invisible.