What's the Difference Between an STI and STD?


Unsplash / @billiebodybrand 

The sexual health language landscape is evolving, becoming both more inclusive and more accurate as it does. Gone are the days when internal condoms were referred to as "female condoms," suction toys as "clit suckers," and pronouns as "preferred pronouns."

And, as of recently, there's another term that likely made frequent appearances in your sex ed classes (if you even had those) that the Centers for Disease Control and Prevention has since suggested that doctors and sex-havers move away from: STD. In its place, they've suggested the term STI.

Why? Below, Felice Gersh, M.D., author of PCOS SOS: A Gynecologist's Lifeline To Naturally Restore Your Rhythms, Hormones and Happiness (Buy It, $17, bookshop.org) answers that as well as some of your other STI and STD questions.

STI and STD, Defined

Both acronyms, STI stands for sexually transmitted infection and STD stands for sexually transmitted disease.

You may have heard STI and STD used interchangeably in the past, but there is a slight difference between infections and diseases, and therefore a slight difference between STIs and STDs, which is why the CDC is making this shift (more on this below).

Still, colloquially both terms are used to categorize the same viral, parasitic, and bacterial conditions that can potentially be transmitted during sex acts: gonorrhea, chlamydia, syphilis, trichomoniasis, HIV, HSV, HPV, etc.


Really, there's just one difference between STIs and STDs: Technically, something is only considered a disease when symptoms are present, explains Dr. Gersh. For example: discoloration, discharge, sores, or soreness. (Related: The Most Common Signs and Symptoms of STDs)

Here's why this differentiation matters: STIs often come with no symptoms. There is a common misconception that an STI will always make itself known via symptoms or alterations in look, feel, taste, texture, or smell — but in reality, nothing could be further from the truth. The majority of sexually transmitted ailments — 66 percent, to be exact — are totally asymptomatic, according to research.

So, a case of gonorrhea that presents with funky discharge and peeing pain (as it might!) could be accurately classified as an STD, while a case of the same infection that is asymptomatic is best classified as an STI. However, the case of symptomatic gonorrhea could also be described as an STI, because the term has been transformed into an umbrella term that encompasses both symptomatic and asymptomatic afflictions.

The CDCs decision to use STI instead of STD is a move towards increased accuracy, says Gersh, because it encompasses all infections, regardless of whether or not there are symptoms.

Because the word "disease" sounds daunting, there's also hope that the switch will help remove the stigma associated with these common infections, as well as increase STI testing frequency. This stigma comes in part from the fact that STIs used to be called "venereal diseases," (which historically have been associated with prostitution, brothels, foreigners, and rule-breaking) and in part by the fact that sex itself has a long history of being considered culturally dirty, taboo, and immoral. (See More: How One Sex Educator Helps People Re-shape Their Understanding of Sex As Dirty)

The Most Common STI Symptom Is No Symptom At All

To be very clear: The presence or absence of symptoms cannot be used to judge the severity of the infection, nor how much damage the infection is causing. "An infection can be totally silent and asymptomatic, but can still be transmitted to others as well as causing harm to your body," says Dr. Gersh.

Most strains of human papillomavirus (HPV), for example, do not cause any symptoms at all. And still, HPV can cause a number of different types of cancers, including cervical cancer, penile cancer, esophageal cancer, and oropharyngeal cancer. If you have a strain of the HPV virus that can cause cervical cancer, for example, you're not going to be able to feel the virus transforming normal cervical cells into cancerous cells, says Dr. Gersh. But still, cancer is developing. "The only way for a person to know if they have HPV is to get tested through a pap smear," she says. (Related: How Often Do You Really Need to Get a Pap Smear?)

Another commonly asymptomatic STI is herpes (HSV). "The vast majority of people with herpes do not have symptoms, but they can still transmit the virus to others during sex," says Dr. Gersh. (For the record: Most doctors and STI testing centers won't test for herpes unless you specifically ask to get tested for herpes. Here's why and how to get tested.)

Syphilis is also often asymptomatic, at least during certain stages of the infection. Sometimes people with syphilis will have no symptoms at the onset or will have symptoms that can easily be explained away. But then, a great many years later, the infection could have progressed to the tertiary stage, which can result in life-altering and life-threatening symptoms such as blindness, organ damage, nerve degeneration, and more, says Dr. Gersh.

Really, the list of STIs that can be both asymptotic *and* causing damage could go on and on...

The Takeaway: Know Your STI Status

Truth be told, whether you call them STIs vs STDs is far less important than knowing your current STI status.

The CDC recommends that (most) sexually active people get tested once per year. But Dr. Gersh actually recommends people get tested more often than that: "Ideally, you'd get tested before every new sexual partner so that you can make an informed decision about out what safer sex practices you're going to use, if any," she says. After all, knowing each other's current STI status is a key element in informed consent, y'all!

She also recommends getting tested two weeks after having unprotected sex with a partner who was STI positive or whose STI status you didn't know. If you get tested too soon after the encounter, you could get a false negative, she says. That's because it takes a bit of time between when you contract an STI and when the body makes antibodies in response to the infection (called the latency period), which is what STI tests pick up on. (More here: How Often Should You Get Tested for STDs?)

If you don't have access to a local STI testing center or feel nervous about the whole thing, another option is to take an at-home STI test, which, yes, are just as accurate as the tests done in doctors' offices (so long as you follow instructions).

But regardless of the testing route you use, "if you receive a positive STI diagnosis it's important to work with your doctor to come up with a treatment or management plan," says Dr. Gersh. In the case that the STI is curable (all bacterial and parasitic STIs are!), it's essential that you take the medicine associated with the treatment plan, she says. Otherwise, you risk spreading the infection out to other partners as well as the infection intensifying.