What are the Most Common Sexually Transmitted Infections?

What are the Most Common Sexually Transmitted Infections?

Created On
Sep 26 2023
Last Updated
Jun 07 2024

Sexually transmitted infections are becoming very common. Here we review a list of STIs (also called STDs), the types of bacteria and viruses causing them, most common symptoms, and STD testing and treatment options.


An infection that spreads through sexual contact is called STI (sexually transmitted infection) or STD (sexually transmitted disease).

When one of the partners is already infected, an STI spreads to the other. And if they have multiple partners, STIs can spread to many people.

Over time, as the newly infected people have sexual relationships with others, the cycle of infection grows to more and more people.

That's why STDs are serious public health problem and affect millions of people.

If not tested in time and treated appropriately, they can cause lot of pain, trauma and even infertility and loss of pregnancy.

The causes of sexually transmitted infections are often bacteria or viruses.

Below we discuss a few common types of STIs, how they spread, the pathogens causing the infection, and recommendations to avoid them.

The graph above lists new and ongoing infections for most common sexually transmitted infections (2018). As you can see, HPV is by far the most common STI in US.

Types of Sexually Transmitted Infections

There are over twenty different STDs or STIs. Here we review a few of them from a long list of STDs.

  • Chlamydia

  • Gonorrhea

  • Syphilis

  • HPV (human papillomavirus)

  • Genital herpes

  • Trichomoniasis

  • Hepatitis B and C (Hep B, Hep C)

  • HIV / AIDS

  • Bacterial Vaginosis

  • Pelvic Inflammatory Disease (PID)

  • Monkeypox

  • Chancroid

  • Lymphogranuloma venereum

  • Mycoplasma genitalium

The risk of each STI varies but Chlamydia, Gonorrhea, and Syphilis are some of the most commonly tracked by the public health authorities including CDC.


Chlamydia is one of the most common STI in teens and young adults that might not show any symptoms.

Chlamydia is caused by a bacterium chlamydia trachomatis.

Use of protection can prevent the spread but one should test as soon as possible to avoid serious risk to health. The CDC recommend that young women should regularly test for chlamydia.

Untreated infection can cause infertility and women might get pelvic inflammatory disease (PID).

PID can cause pain around pelvis during sex or while peeing and bleeding during sex which can be heavy during menstrual cycle.

A discreet at home chlamydia test is an easy way to confirm the symptoms before starting a treatment.


Gonorrhea is very common STI caused by the bacterium Neisseria gonorrhoeae.

The symptoms might be mild or even delayed for a long time but are very similar to Chlamydia and pelvic inflammatory disease (PID).

Gonorrhea often causes pain while urinating and pus-like discharge.

Men might observe pain in testicles and women might notice pain in their lower belly. It is recommended to use protection or test regularly whenever you have or your partner are sexually active outside your relationship.


The STD syphilis is caused by the bacterium Treponema pallidum.

The graph in the image above shows a five-fold increase in syphilis over past 20 years.

Once infected, syphilis progresses through four stages.

At first, painless sores and warts appear around the groin, genitals, and mouth for 2-3 weeks as the bacteria incubate.

As these disappear, the second stage involves rashes on palms of hands and soles of the feet lasting 2-4 weeks. You may see other symptoms including mild fever, swollen glands, body ache, fatigue, sore throat, itching, loss of hair in random patches or weight loss.

The third stage is called latent stage without any symptoms for months or even years before returning as the final stage called tertiary syphilis which can lead to serious consequences including damage to heart, brain, liver, eyes, and joints. It can also transfer from mothers to babies.

Syphilis is easily treatable with antibiotics but requires testing to confirm an infection.

HPV (Human Papillomavirus)

HPV is the most common STI worldwide. Almost 1 in 6 people is infected with HPV in the world at any given time.

But there is no way to confirm an HPV infection since symptoms are rare and people might not know they are infected.

Some people may observe genital warts and women might see abnormal precancerous cells on the cervix.

HPV is not a single virus, but a group that can be tested in women with a vaginal swab before it can lead to cervical cancer.

There is no cure for HPV, but an early STD testing and regular pep-smears can help detect any infections. HPV vaccines are available today and recommended for those under the age of 26 years.


Genital herpes is a common sexually transmitted infection but it is a relatively low risk STD.

Herpes is caused by the Herpes simplex virus which causes sores and blisters on the mouth (called HSV-1) and genitals (HSV-2).

Normally, herpes sores heal in 2-4 weeks. But they may reappear four-five times in a year causing a herpes outbreak.

Flu-like symptoms of chills, fever, body pain are also common.

There is no cure, but anti-viral medicine can help in potential outbreaks. Safe sex and a herpes STD test can help prevent the infection.

Trich or Trichomoniasis

The STD Trichomoniasis or Trich is caused by a parasite trichomonas vaginalis.

After HPV and HSV, it is one of the most common STD in America.

You may have a Trich infection and may not know it. That's because Trichomoniasis symptoms are not always clearly visible. But a Trich STD test might be able to easily detect it.

Women are more commonly infected than men and are likely to show the symptoms.

Trich is easily treatable with antibiotics. But it's important to get tested first.

If you suspect a Trich STI for yourself or your partner, the CDC recommend to go to an STD testing clinic near you.

Or you can order one of the at-home STD test kits, which are as accurate and affordable.

They also offer the privacy and security one desires for such a personal matter.

Bacterial Vaginosis

The STI Bacterial Vaginosis is not fully understood yet.

However, women who will multiple partners or use a douche or have an IUD (intrauterine device) for birth control are at higher risk of BV infection.

Symptoms of BV are not clear, but you may see an unusual discharge, itching or fish-like smell from vaginal area. The symptoms of Bacterial Vaginosis often appear after having sex.


HIV is the most famous sexually transmitted virus. Human immunodeficiency Virus attacks the immune system, making it extremely difficult for our body to fight it.

If untreated, it can result into AIDS (Acquired Immunodeficiency Syndrome), which is a serious condition that has killed millions of people over past four decades.

Today, antiretroviral therapy and other medical breakthroughs have made it possible to live a normal healthy life. However, protected sex and PrEp (pre-exposure prophylaxis) can effectively avoid spread of HIV.

Hepatitis B and Hepatitis C

These are viral infections that can damage the liver. Besides sexual transmission, they can also spread via blood transfusion and sharing needles (e.g., during drug use).

They may not always show any symptoms but often appear as pain in the abdomen region, yellow eyes and skin, dark urine, and fatigue. Hepatitis B can be prevented with vaccination.


Mpox is a relatively new sexually transmitted disease that results in sores and lesions on the body.

This viral disease can spread through kissing, touching or sex, especially in men having relationships with other men.

A new vaccine is now available and it is easy to get tested for monkeypox.


A short summary of 2022 data above from CDC say risk of different types of STDs to public health is growing.

STDs are huge burden on society due to the pain and suffering they cause. They consume public health resources that can be used elsewhere.

The stigma around STDs can prevent people from getting timely diagnosis and treatment. However, it is very easy to get tested for most of them.

An easy, simple swab or urine sample collected from the privacy of your home can help one get tested for STDs.

RxHomeTest offers multiple options to get tested and seek treatment as early as possible.

Order an Advanced STD Test.


  1. Sexually Transmitted Infections: Adopting a Sexual Health Paradigm (2021) - National Academies Report.

  2. CDC: Sexually Transmitted Diseases: Prevention, Testing, Treatment.