The Most Common Sexually Transmitted Diseases and How They Spread
Sexually transmitted diseases are usual suspects in sexual health, but not everyone knows how they move from person to person. Some, like HIV, need fluid exchange. Others, like herpes and HPV, spread through bare skin. A leaving-behind stigma only clouds the facts. This guide explores the most prevalent STDs, how each one transmits, what makes them so common, and what you can actually do about it.
30 July 2025
12 min read
6452
Quick Answer: The most common STDs globally are HPV, chlamydia, gonorrhea, syphilis, trichomoniasis, herpes, HIV, and hepatitis B. Four are bacterial or parasitic and curable; four are viral and manageable. Transmission happens mostly during vaginal, anal, oral, or genital touching, through fluids or skin-to-skin contact. Each infection has its own timeline, risk level, and stealth factor.
HPV: The Silent Virus Most of Us Get
Human papillomavirus (HPV) is the most commonly transmitted infection in the U.S., estimated at 75–80% of sexually active people by age 50. HPV spreads through direct skin-to-skin contact during vaginal, anal, or oral sex, no fluid required. It often shows no symptoms; some types cause genital warts, others lead to cancers of cervix, anus, throat, or penis over time. Vaccines protect against the highest-risk strains, but once you’re exposed, your body must fight the virus on its own.
These bacterial infections are the most commonly reported STDs in the U.S., chlamydia had over 1.6 million cases in 2023, with gonorrhea ranking second at over 600k cases. Both can be passed during oral, anal, vaginal, or even manual sex, via semen, vaginal fluid, or infected tissue. Often symptom-free, they can lead to pelvic inflammatory disease, infertility, chronic pain, or higher HIV risk if left untreated. Fortunately, a short course of antibiotics cures most cases, but reinfection is common unless all partners are treated.
Syphilis: The Old Disease That Never Left
Syphilis is making a terrifying comeback, especially among young adults, gay and bisexual men, and people experiencing homelessness. Once thought of as a “disease of the past,” it’s now one of the fastest-rising STDs globally, with congenital (mother-to-baby) cases increasing year after year. Syphilis spreads during vaginal, anal, or oral sex through contact with a syphilitic sore (called a chancre), which is often painless and hidden inside the mouth, vagina, or rectum. Because it can be invisible and symptom-free in early stages, many people pass it unknowingly.
The infection unfolds in stages. The primary stage starts with one or more painless sores. The secondary stage might bring a rash, flu-like symptoms, or patchy hair loss. Left untreated, syphilis can enter a latent stage for years, until it strikes again as neurosyphilis, damaging the brain, heart, and other organs. Fortunately, penicillin injections cure all stages, but early detection is crucial. The shame surrounding syphilis often delays testing, making education and access urgent.
The parasite trichomoniasis doesn't get talked about enough.
Trichomoniasis, or "trich," is a sexually transmitted disease that is not caused by bacteria or viruses, but by a parasite called Trichomonas vaginalis. It's very common, especially among people with vaginas, but tests for it are very rare. Trich spreads through contact between the penis and vagina, the vagina and vagina, or shared sex toys. It doesn't spread through fluids as much as it does through contact with infected genital tissues or surfaces. The fact that trich is so subtle is what makes it dangerous; about 70% of people who have it don't show any symptoms. But if you don't treat it during pregnancy, it can make you more likely to get other STDs and have a baby too soon.
If you have symptoms, they could include itching, strange discharge, painful urination, or a strong smell. But again, a lot of people don't notice anything at all. A single dose of metronidazole or tinidazole usually gets rid of the infection, but partners who aren't treated at the same time often get it again. Even though trich is very common, it is often left out of routine panels unless someone asks for it. This shows how important it is to do full testing.
Herpes (HSV-1 and HSV-2): More Than Just a Cold Sore
Herpes simplex virus comes in two types: HSV-1, typically associated with oral infections (cold sores), and HSV-2, which usually causes genital outbreaks. But the line has blurred. Thanks to oral sex, HSV-1 increasingly causes genital herpes. Transmission occurs through direct skin-to-skin contact, even when no sores are visible, during kissing, oral, vaginal, or anal sex. Herpes isn’t passed by fluids. It’s a contact virus, and it’s estimated that 1 in 6 people between 14–49 in the U.S. has genital HSV-2, while over half carry HSV-1.
Outbreaks can cause painful blisters or just tingling or itching without any sores. A lot of people don't find out they have it until years later, usually during routine STD tests or when they have a flare-up caused by stress or illness. There is no cure for herpes, but antiviral drugs like valacyclovir can help lower the number of outbreaks and the amount of virus that is shed, which lowers the chance of transmission. Using condoms or dental dams during sex is helpful, but it won't completely get rid of the risk if skin outside the barrier is affected.
The Virus That Changed Sexual Health for Good: HIV
The human immunodeficiency virus (HIV) is mostly spread through blood, breast milk, vaginal fluid, rectal fluid, and semen. You can't get it by touching, kissing, or sharing food. You can get it from having sex without protection, sharing needles, or giving birth without medical help. If you don't get treatment, HIV can attack the T-cells in your immune system and make you sick with AIDS (Acquired Immunodeficiency Syndrome). But thanks to medical advances, HIV is now a long-term illness that can be managed, and it's never been easier to avoid getting it.
PrEP (pre-exposure prophylaxis) and PEP (post-exposure prophylaxis) can stop the spread of disease before or after someone is exposed to it. ART (antiretroviral therapy) lowers the amount of virus in people with HIV, making it impossible to find or pass on (U=U). It's important to get tested often, especially after meeting someone new or having sex with a new partner. Because of the stigma around HIV, many people still can't get care. But science and community advocacy are changing that.
Hepatitis B: The STI That Gets Ignored
The hepatitis B virus (HBV) spreads through blood, semen, and vaginal fluids and causes liver inflammation. People often think of HBV as a virus that people get from IV drug use or in hospitals, but it can also be spread through sexual contact, especially when anal, vaginal, or oral sex is not protected. It can live outside the body for up to a week and still be contagious, so sharing razors, toothbrushes, and body fluids is dangerous.
Symptoms may include fatigue, nausea, yellowing skin (jaundice), or dark urine, but many people never notice anything until liver damage is advanced. The good news? There’s an effective vaccine. Routine immunization of infants has reduced rates dramatically, but adults, especially sexually active people who weren’t vaccinated as kids, should check their immunity status. Chronic HBV can be managed with antivirals, but prevention through vaccination remains the most powerful tool we have.
Asymptomatic Spread: The Quiet Reason STDs Go Unnoticed
One of the most dangerous realities of STDs is that most people who have one don’t know it. That’s not because they’re careless, it’s because many STDs, especially chlamydia, gonorrhea, herpes, and trichomoniasis, cause little to no symptoms. In fact, the CDC estimates that up to 90% of people with herpes don’t realize they have it. Likewise, chlamydia often hides in the body for months without signs, yet silently damages the reproductive system in the background.
This stealth factor makes it easy for STDs to spread within relationships, even monogamous ones. A partner may believe they’re healthy because they “feel fine,” but may be unknowingly passing an infection. Asymptomatic spread is also why routine screening is so critical. Waiting for symptoms isn’t a reliable strategy. For sexually active people under 25, or anyone with new or multiple partners, testing every 3–6 months can make all the difference between early treatment and long-term complications.
What Doesn't Transmit STDs (but people think it does)
Let’s bust a few myths. You can’t catch STDs from toilet seats, hugging, sharing drinks, or using the same gym equipment. Most STDs require intimate contact, either fluid exchange or direct skin-to-skin interaction in the genital, anal, or oral regions. Herpes doesn’t travel on clothing. Gonorrhea won’t survive on a towel. HIV isn’t hiding on a shared spoon.
That said, some borderline scenarios exist. Hepatitis B and HIV, for example, can be passed through shared needles or in rare cases via contaminated instruments. Trichomoniasis could theoretically live briefly on wet surfaces like shared sex toys if not cleaned. But most STDs are fragile outside the human body. What’s more dangerous than surfaces is assumptions, assuming your partner is clean because they look healthy or because they’re “not the type.” That’s why mutual testing and honest conversation matter more than guessing.
The STDs that spread through skin-to-skin contact: why condoms don't protect you from everything
Using condoms and dental dams is a great way to lower your risk of STDs, especially for infections that spread through fluids, like HIV, chlamydia, gonorrhea, and hepatitis B. But things get more complicated when it comes to skin-to-skin infections like herpes, HPV, and syphilis. You can get these STDs by touching your thighs, testicles, pubic area, or labia, which are not covered by condoms. Even if you wear protection, there is still a risk if there is a sore or lesion on your skin that isn't covered.
That doesn’t mean protection is pointless, just that it’s not perfect. Herpes, for instance, sheds virus even when no blisters are present. HPV can transmit through micro-abrasions in the skin. And syphilis sores are often missed entirely. This is why risk reduction includes more than just barriers. It involves open partner discussions, symptom checks, and routine testing, even when things look and feel “normal.”
Oral sex is often considered a “safer” alternative, but it’s not risk-free. In fact, many STDs can be transmitted via oral-genital contact, including herpes, gonorrhea, chlamydia, syphilis, HPV, and HIV (though less commonly). Throat gonorrhea (pharyngeal gonorrhea) is rising fast, particularly among men who have sex with men, and is often completely asymptomatic, making it hard to detect and easy to spread.
Dental dams or condoms used during oral can reduce risk, but most people don’t use them. That’s partly cultural, and partly because oral sex is wrongly assumed to be “cleaner.” The truth? STDs don’t care whether a penis or a tongue made contact. If there’s viral shedding or infected fluid present, it’s enough to cause transmission. If oral is on the menu, it should also be in your testing routine.
FAQs
1. Is it possible to get an STD the first time you have sex?
Yes. You can get an STD from having sex with someone who is already infected, whether it's oral, vaginal, or anal.
2. Do condoms keep you safe from all STDs?
They do a good job of keeping you safe from STDs that spread through fluids, like HIV and chlamydia. However, they don't work as well for skin-to-skin infections like herpes or HPV.
3. Which STD is the most common?
The most common sexually transmitted disease (STD) in the world is HPV (human papillomavirus), followed by herpes and chlamydia.
4. Is it possible to get an STD from oral sex?
Yes. Oral sex can spread herpes, gonorrhea, syphilis, and HPV.
5. How long after sex should I get tested?
Most STDs show up in 1 to 3 weeks, but for HIV, hepatitis, or syphilis, it's best to wait 4 to 6 weeks for the most accurate results.
6. What are the signs of common STDs?
They can be different, but they might include discharge, burning when you urinate, sores, itching, or no symptoms at all.
7. Is it possible to get rid of an STD?
You can get rid of some STDs, like chlamydia, gonorrhea, and trich. Some diseases, like herpes or HIV, can be controlled with medicine.
8. How often should I get tested?
If you're under 25 or have new or multiple partners, get tested every 3 to 6 months. If a condom slips or you have any symptoms, get tested right away.
9. Can you test at home?
Yes. The FDA has given the green light to STD test kits that people can use at home. They are very accurate for most common STDs.
10. What should I say to my partner about STDs?
Be truthful and give facts first. Testing should show that you care and trust someone, not that you don't.
Be truthful and give facts first. Testing should show that you care and trust someone, not that you don't.
You deserve the truth, not fear. One thing we've learned from looking at all these infections is that STDs don't care who you are. They don't care if you're a man or a woman, gay or straight, single or in a relationship, or how many partners you have. You can still get one even if you're monogamous. You can still get something even if you use condoms. The disease isn't the problem; the problem is that we haven't taught people enough about their bodies, the risks they face, and the options they have.
Knowing how STDs spread isn’t about fear. It’s about freedom. The freedom to get tested without shame. The freedom to protect yourself without panic. And the freedom to love, explore, and have sex without gambling with your health.
STD Rapid Test Kits offers discreet, accurate, lab-verified testing delivered straight to your door. No appointments. No judgment. Just answers.
For Women
Results in Minutes
No Lab Needed
Private & Discreet
For Men & Women
