What’s The Difference Between STI vs STD?

By Jennifer Nadel, MD
Medically reviewed checkmarkMedically reviewed
February 15, 2022

Do you ever get confused about the difference between an STI and an STD? You might have heard the two terms used interchangeably, but there is an important distinction between them. 

An STI is a sexually transmitted infection, while an STD is a sexually transmitted disease. Every STI is caused by a bacteria or a virus, which can progress into an STD. Every STD begins as an STI.

If you’re still unsure whether you should use the term STI versus STD, it’s totally understandable — let’s go over the origin of the terms, how to get tested, how to find STI and STD support, and more. 

Origin of Terminology

Before the term STD became common practice, the term “venereal disease” was used in its place. However, over the years, the medical community has also begun to shift away from the term STD. 

One of the major reasons STI has become commonplace is due to the stigma associated with having an STD. This is because referring to something as a “disease” may have a negative connotation.

An infection has not yet developed into a disease, so it’s perceived as being less serious. After all, an infection can still be treated and cured. Doctors want to stop the spread of STDs, so reducing the stigma around an STI may encourage more people to get tested. 

The other reason for the shift in language is due to the literal definitions of these words. STIs do not have any symptoms, so technically, it is not yet a disease. A disease is an advanced stage of infection.

Which Term Do Doctors Use? 

Doctors have started to prefer the term STI over STD. However, this can ultimately depend on the nature of the doctor’s visit and the patient’s health. 

An STD is an advanced form of an STI. A disease has clear symptoms and disrupts the body’s natural processes.

If you start to show symptoms, like in the case of genital herpes, then your doctor will use the term STD. STIs may go away on their own before developing into a disease.

For example, some strains of the human papillomavirus (HPV) never present symptoms and are removed from the body naturally. In this particular case, the infection did not develop into a disease. 

There is also a stigma surrounding the term STD. If there is less of a stigma around the word infection, the thinking is that more people will get tested and treated.

Which Term Should You Use? 

It’s entirely up to you! However, if you’re being medically accurate, there are differences between the two terms. Unless you are presenting clear symptoms, then you probably only have an infection or an STI. 

An STD is a more advanced stage of an STI. Other than that difference, it’s okay to use either one in everyday life. Also, major medical organizations have not come to a clear consensus on which term to use.

The Centers for Disease Control and Prevention (CDC) use both terms interchangeably. In comparison, The American College of Obstetricians and Gynecologists (ACOG) prefers to stick to the term STI.

Disease Vs Infection

Disease is the manifestation of advanced infection. When a patient shows clear signs of symptoms and medical issues, there is usually a disease in their body. 

An infection is the first step on the journey to a disease. All STDs begin as STIs. The medical community is moving away from the term STD since many STIs do not present symptoms. 

Common STIs like chlamydia and gonorrhea rarely present symptoms. If left untreated, both of them can develop into pelvic inflammatory disease (PID), which is a serious pelvic infection. 

Among many possible complications it can lead to infertility. It is more medically accurate to refer to chlamydia and gonorrhea as STIs.


As previously stated, many STIs do not show symptoms. If they do, their symptoms may be misleading or take years to appear. If you don’t get tested, then you could develop an STD, which could cause serious health issues.

Keep in mind that all sexual activity is capable of spreading an STI. In addition to vaginal, anal, and oral sex, other activities like kissing, making genital contact, or genital touching can spread an STI. 

It’s important to be knowledgeable about possible symptoms, so you know what to look out for:

  • HPV: There are over 100 strains of HPV, and many do not show symptoms and simply go away on their own. However, the few that do show symptoms can develop into genital warts or cancer. Genital warts look like small, elevated bumps in your genital area. There are three vaccines (Cervarix, Gardasil, Gardasil-9) that can prevent HPV. If you are under 45 years of age, you should talk to your doctor about getting one of these vaccines.
  • Genital Herpes: Genital herpes will present itself as painful blisters around the genital or anus area. You may or may not be able to see them as they can hide inside the genitals and are difficult to spot. Keep in mind not everyone with genital herpes will have blisters, and you can still pass along the STI even without them. 
  • Chlamydia: Chlamydia rarely shows symptoms in its carriers. However, if you do have symptoms, you may feel painful burning while you pee or unusual colored discharge from your penis or vagina. Some people with vaginas might mistake chlamydia for a yeast infection
  • Gonorrhea: People with penises are more likely than people with vaginas to have symptoms with gonorrhea. This STI is very similar to chlamydia and presents similar symptoms.  You may experience painful urination or strange discharge from the penis or vagina.
  • Syphilis: Syphilis has multiple stages, some that have symptoms and some that don’t. The first stage is a painslee sore that can look like a bump or an ingrown hair. The second stage is a rash and possible mouth and genital sores. The third stage shows no symptoms before approaching the final stage. In the final stage, you may have brain or organ damage.
  • Trichomoniasis: Symptoms of trichomoniasis include sore and itchy genitals and smelly, yellowish, or greenish discharge. 

Here are some other symptoms that are non-specific to an STI but can still indicate a medical issue: 

  • Burning urination 
  • Unusual discharge 
  • Bumps, rashes, or sores in the genital area 
  • Pain during sex 
  • Bleeding around the anus 
  • Itchy genitals 
  • Pelvic pain 

How to Get Tested

Since STIs rarely show symptoms, you may have no idea if you have one. The CDC recommends sexually active people get tested at least once a year.

Some doctors even recommend getting tested each time they have a new partner. Unless you get tested, you may not know you have an STI.

If you let your STI go untreated, it could develop into serious medical problems later in your life. Ultimately, knowledge is power.

If you know your sexual history, then you can better inform your sexual partners. You can get tested by making an appointment with your general practitioner, gynecologist, or going to a health clinic.

The CDC even provides a handy search tool to find a testing site near you. 

You should get screened for STIs if: 

  • You had sex without a condom 
  • You have sex with multiple partners
  • You think you have an STI
  • You were told by a partner to get tested
  • You have a new partner 
  • You shared an injection needle 
  • You have never tested before
  • You are at your yearly testing period 
  • You are pregnant 

STI & STD Support 

If you’re looking to find support for living with your STI and STD, there are plenty of support groups that can be of assistance.

This website by the STI Support Project provides a resource of support groups in the United States and other countries. Remember that you are not alone, and millions of people are also living with an STI or STD.  There is also a list of resources provided by STD Aware to help with general support surrounding your STI or STD. 

When to See a Doctor

You should see a doctor if you suspect you have an STI or STD, or if you have any concerning symptoms. You should also see your doctor for your annual STI screening, or if you have recently had unprotected sex.

How K Health Can Help

Did you know you can access online urgent care with K Health?

Check your symptoms, explore conditions and treatments, and if needed, text with a healthcare provider in minutes. 

K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

Which is worse, STD or STI?
It’s not necessarily that one is worse than the other. All STDs start as STIs or infections. So, you will have an STI first before it advances into an STD.
Why do we say STI instead of STD?
STI is becoming a more common practice in the medical community because of the stigma surrounding STDs. Doctors want to make sure people are getting tested as often as possible, so reducing the stigma may help more people get tested. Additionally, many STDs do not show symptoms or go unnoticed, so it’s more medically accurate to call them STIs. An infection is the first stop on the road to disease.
Is Chlamydia an STD or STI?
Chlamydia is an infection, so it is an STI. It is a bacteria infection and can be treated and cured with antibiotics like azithromycin (Zithromax). However, if chlamydia goes untreated, it can develop into pelvic inflammatory disease (PID).
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Jennifer Nadel, MD

Dr. Jennifer Nadel is a board certified emergency medicine physician and received her medical degree from the George Washington University School of Medicine. She has worked in varied practice environments, including academic urban level-one trauma centers, community hospital emergency departments, skilled nursing facilities, telemedicine, EMS medical control, and flight medicine.