Illustration of sexually transmitted infection (STI vs. STD)

STI vs. STD: what’s the difference?

Written on November 28, 2022 by Gillian (Gigi) Singer, MPH, Sexuality Educator & Certified Sexologist. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

Sexually transmitted infections (STIs) and sexually transmitted diseases (STDs) are both incredibly common—according to the CDC, there are millions of new infections every year in the United States [1].

You may have noticed that I referred to both “STDs” and “STIs” rather than just one of the two. The abbreviations “STI” and “STD” are frequently used interchangeably to describe sexually transmitted conditions…but what if I told you that they weren’t technically the same thing?

The key difference between STIs and STDs can be identified by the implications of one small linguistic distinction: the use of “infection” in place of “disease” (and vice versa). Infections and diseases are not the same things—infections are curable and go away, while diseases are usually chronic (ongoing or life-long).

Sexually transmitted infections (STIs)

In a topical glossary created by public health experts, infections are defined as “the entrance and development of an infectious agent in a human or animal body, whether or not it develops into an infectious disease” [2].

STIs can be caused by bacteria or by parasites and are curable and often quickly resolved.

Basically, when the diagnosed condition is going to go away, it is a temporary infection. Here are some examples of both bacterial and parasitic common STIs.

Bacterial Vaginosis (BV)

BV can also occur without sexual transmission and falls under the category of vaginitis. Symptoms can be similar to yeast infections (yeast infections can be sexually transmitted). BV is treated with antibiotics prescribed by a healthcare provider.


Chlamydia is caused by a bacterium called Chlamydia trachomatis and is most common in vulva owners between the ages of 19 and 25. Chlamydia is treated with antibiotics prescribed by a healthcare provider and should be treated promptly to prevent the development of Pelvic Inflammatory Disease (PID).

Learn more about chlamydia and how to get tested here.


Gonorrhea is a result of a bacterium called Neisseria gonorrhoeae and should be treated as soon as possible to prevent further infection and damage to reproductive organs. Gonorrhea is treated with antibiotics prescribed by a healthcare provider.

Learn more about gonorrhea and how to get tested here.


Syphilis is caused by treponema pallidum, and tests can detect past or active syphilis infections. In 2020, the CDC was notified of nearly 134,000 new cases of syphilis. Syphilis is treated with antibiotics prescribed by a healthcare provider.

Learn more about syphilis and how to get tested here.


Trichomoniasis is a parasitic infection; the parasite is called Trichomonas vaginalis. When untreated, vulva owners can be infected for weeks and even years, whereas penis owners’ infections last less than two weeks. Trichomoniasis is treated with antibiotics prescribed by a healthcare provider.

Learn more about the trichomoniasis test.

Pubic lice

This infection is parasitic and usually referred to as “crabs.” Treatment is very similar to what you would do if you got head lice—you use medicated creams and/or you can remove hair.

Pelvic inflammatory disease (PID)

While PID is curable, if untreated, it can cause permanent damage to reproductive organs (which can impact fertility, etc.) PID is treated with antibiotics prescribed by a healthcare provider.

Sexually transmitted diseases (STDs)

STDs are caused by viruses that, once they enter your body, remain in your body—because they remain (active or dormant), they are considered ongoing diseases.

Dr. Milton Taylor, a microbiologist, in layman’s terms, defines viruses as packages of genetic information that enter other cells, take over, and then either kill the host cell and/or continue to replicate themselves [3]. Viruses use the cells in your body to recreate themselves [3].

Here are some examples of viral STDs.


Hepatitis C (HCV) requires treatment since it can trigger a variety of symptoms and also can result in liver disease, liver failure, or liver cancer.

Learn more about trichomoniasis and how to get tested here.


Herpes is a result of the herpes simplex virus (HSV) and can be commonly found on the genitals and in the mouth. The CDC estimated that “572,000 new genital herpes infections in the United States among people aged 14 to 49” occurred in 2018 [4].


Human immunodeficiency virus (HIV) is chronic and is something that you will manage for the rest of your life. Luckily, HIV medicine can decrease the amount of the virus in your body, and you can live a long life (and also have a robust sex life).

Learn more about HIV and how to get tested here.


Human papillomavirus (HPV) is the most common STD in the United States [5]. The CDC says “In most cases (9 out of 10), HPV goes away on its own within two years without health problems. But when HPV does not go away, it can cause health problems like genital warts and cancer” [5].

How do you get a sexually transmitted disease or infection?

STDs and STIs are primarily spread through sexual contact, including vaginal, anal, and oral sex. According to the Centers for Disease Control and Prevention (CDC), some STDs and STIs can also be transmitted through skin-to-skin contact with infected areas or fluids, such as kissing or sharing sex toys.

What do STIs and STDs have in common?

The first thing STIs and STDs have in common is that they are both sexually transmitted, meaning they are passed from one person to another via sexual contact. Second, both require STI or STD testing for diagnosis (with few exceptions).

Luckily, Everlywell has your back and wants to ensure that you get the testing you need. Browse our options for discreet, at-home sexual health testing kits, which include options such as the HCV Test and Syphilis Test. If your lab results are abnormal, Everlywell will also connect you with its national independent physician network for consultation and appropriate treatment.

STDs vs. STIs: is there a difference?

Let’s talk about safe sex: How to talk about STIs/STDs with a new partner

How to prevent STDs: key steps you can take


  1. CDC - STD Diseases & Related Conditions. Centers for Disease Control and Prevention. URL. Published December 8, 2021. Accessed November 14, 2022.
  2. Barreto ML, Teixeira MG, Carmo EH. Infectious diseases epidemiology. J Epidemiol Community Health. 2006;60(3):192-195. doi:10.1136/jech.2003.011593. Accessed November 14, 2022.
  3. Taylor MW. What Is a Virus? Viruses and Man: A History of Interactions. 2014;23-40. Published 2014 Jul 22. doi:10.1007/978-3-319-07758-1_2. Accessed November 14, 2022.
  4. STD Facts - Genital herpes. Centers for Disease Control and Prevention. URL. Published January 3, 2022. Accessed November 14, 2022.
  5. STD Facts - Human Papillomavirus (HPV). Centers for Disease Control and Prevention. URL. Published April 12, 2022. Accessed November 14, 2022.
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