What’s the difference between STIs and STDs?

The question  “What is the difference between STIs and STDs?” comes up all the time, especially since, when talking or reading about sexual health, the term STI is becoming more and more common. STD vs STI: They are not exactly the same.

What’s an STI?

An STI is a sexually transmitted infection, and an STD is a sexually transmitted disease.

STDs and STIs are often used interchangeably and as synonyms, but they technically mean different things. We’ll dive into greater details about their exact differences below.


Technically, STIs and STDs differ– Having an STI means that an individual has an infection, but that it has not yet developed into a disease. Take HPV (human papillomavirus) for instance: Typically a woman with HPV does not have any symptoms, but she carries the virus. She has an STI; but if she develops cervical cancer from HPV, she now has an STD since cancer is a disease. The same is true for individuals who have chlamydia or gonorrhea infections that develop into pelvic inflammatory disease (PID).

STD (Sexually Transmitted Disease): refers to the infection itself.

STD (Sexually Transmitted Disease) is a general term that refers to a variety of diseases that are spread by sexual contact, including HIV, herpes and HPV. Some STDs can be passed from one person to another during vaginal, anal or oral sex. Others can be passed from one person to another through blood (for example hepatitis B virus).

STI (Sexually Transmitted Infection): refers to the infection and inflammation caused by the infection.

The term STI (Sexually Transmitted Infection) refers to infections that are passed through sexual contact. STIs are divided into two groups: bacterial infections and viral infections. Bacterial STIs include gonorrhea, chlamydia, syphilis, and trichomoniasis. 

Symptoms may be present with an STI but not an STD, or vice versa.

Sometimes the symptoms of a STD are present without an STI, or vice versa. For example, many men and women experience frequent urination when they have an STI in the urinary tract. This symptom is also common among women who have UTIs (urinary tract infections) that are not caused by an STI. If you experience frequent urination, it’s important to see your doctor so they can diagnose what’s causing it and treat it appropriately.

The terms are often used interchangeably, but they are not completely synonymous.

The real question here is: What’s the difference between infection and disease? An infection or STI disease is often the first step of a disease and occurs when either bacteria or viruses enter the body and start multiplying. The disruption of normal body function or structure, especially when signs and symptoms appear, is considered STI disease (as long as the cause is not the result of a physical injury).

It’s important to note that the terms STD and STI are not completely synonymous. 

When you’re seeking medical advice or treatment for an STI, your health care provider will likely ask if you have symptoms of an infection like discharge or pain. If they do, they’ll recommend getting tested for one of more than a dozen different types of sexually transmitted infections (STIs). 

This means, medically speaking, that all STDs start out as STIs. STIs that progress into disease are STDs.

The usage of STI is becoming seemingly more preferred by the health world thanks in part to a less negative stigma. STDs have been around forever– think back to junior high health classes. But the phrase “sexually transmitted infection” doesn’t yet have the same negative connotation attached to it, so doctors and health advisors are more than happy to use the term infection rather than disease.

When you think of STDs, you might picture the familiar sores or blisters that come with some infections. But not every STD causes inflammation like this. In fact, most STDs are asymptomatic—meaning they don’t cause symptoms at all! The main difference between STIs and STDs is that while STIs include infections that may not have symptoms, like HIV and HPV (human papillomavirus), they aren’t accompanied by any inflammation.

In contrast to an infection alone, an STD can be caused by more than one organism; for example HIV can be passed on through both blood-to-blood contact (for example sharing needles) and sexual intercourse. It’s important to think about when you’re exposed to these microbes: if it’s through sexual contact, then it’s considered an STD; if not then it’s more likely just an ordinary infection caused by a single microbe.


In the end, it really doesn’t matter what you call them. The important thing is that you know which infections are sexually transmitted and which ones aren’t so that you can protect yourself accordingly. Read more of our articles to educate yourself and get std tested at one of our private labs if you have questions about your STD/STI status.

Medically Reviewed by on August 1, 2022

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Author: Nick Corlis

Nick Corlis is a writer, marketer, and designer. He graduated from Texas State University in San Marcos, Texas, with a degree in Digital Communications. Nick is proud to be able to help eliminate the stigma of STD testing through his writing and is always trying to advocate the importance of your sexual health. Before STDcheck, his favorite way to develop his writing skills was by accepting various writing jobs in college and maintaining multiple blogs. Nick wears many hats here at STDcheck, but specifically enjoys writing accurate, well-researched content that is not only informative and relatable but sometimes also contains memes. When not writing, Nick likes to race cars and go-karts, eat Japanese food, and play games on his computer.