STI vs STD: Do They Mean the Same Thing?

STI or STD? It can be confusing to know which to say. You probably heard both terms in health class and have seen them both used online. "STI" stands for sexually transmitted infection, and "STD" stands for sexually transmitted disease. But which is the correct term for all the different sexually transmitted conditions?

Read on to find out.

STI vs STD: Which Term Should You Use?

It's OK to use the terms interchangeably, H. Hunter Handsfield, MD, professor emeritus of medicine at the Center for AIDS and STD at the University of Washington, told Health. "In day-to-day uses of the term, there is no real difference," Handsfield said.

There's no distinct consensus among the major organizations, either. For instance, the American College of Obstetricians and Gynecologists (ACOG) appears to be more likely to use STI. The Centers for Disease Control and Prevention (CDC) uses STD and STI interchangeably, noting that STDs are also known as STIs.

No matter which term you use, the diseases/infections, such as chlamydia, gonorrhea, and syphilis, are passed through vaginal, anal, and oral sexual activity—and they are conditions one in five people in the United States have, according to the CDC.

'Disease' vs 'Infection'

While people might be able to use the terms interchangeably in day-to-day convos, there are differences between the terms "disease" and "infection."

Technically, a disease is considered an advanced form of an infection, Damian "Pat" Alagia, MD, ob-gyn and the senior medical director for advanced diagnostics and women's health at Quest Diagnostics, told Health.

For example, "If a chlamydia or gonorrhea infection takes off and is untreated or improperly treated, it can progress into pelvic inflammatory disease (PID), which is a complication of the STI that can threaten fertility," Dr. Alagia said. "A disease is a full-blown expression of the underlying infection."

By contrast, the term STI is a term that "largely evolved from the realization of asymptomatic infections," Dr. Handsfield explained. In other words, bacteria or viruses can cause an infection, but that infection might not have any outward signs or symptoms. Sometimes, the condition—like the human papillomavirus (HPV)—is cleared by the body and goes away. In these cases, the virus did not cause disease.

But that doesn't mean the infection is any less important—or that it should be ignored.

There are many instances when you want to respond to an infection even if there are no symptoms because it can still cause disease, Dr. Handsfield said. That's why chlamydia and gonorrhea—largely infections without noticeable symptoms—are treated with antibiotics if diagnosed.

It's also why experts encourage people to get HPV screening and pap tests. The idea is that certain HPV infections, which are usually asymptomatic, can cause cervical cancer. Knowing if you are infected with high-risk HPV will help a healthcare provider determine any necessary follow-up testing or treat any precancerous lesions to prevent them from progressing into cancer.

Though there is technically a difference between "disease" and "infection," whether you use STD or STI doesn't matter; it shouldn't change testing, treatment, or other steps you take to safeguard yourself and your sexual partners, Dr. Alagia said.

And, STI or STD, you'll still want to use the same measures to protect yourself and your partners, such as having an open discussion about sexual history, using condoms, and getting tested for STIs regularly.

Which Term Do Health Care Experts Use?

Your doctor may use one or the other depending on their age, training, or preference, Dr. Handsfield said. It may also have to do with the patient population they see most. If they're doing a lot of screening in their practice, they may use STIs. But, if they're treating symptomatic infections or diseases, they may use STDs.

While it's not wrong to use STD, the needle is moving slightly toward using STI, Dr. Handsfield noted. That change might destigmatize these sexually transmitted conditions. As Dr. Handsfield wrote in a 2017 editorial, some limited research suggests there may be less stigma surrounding STIs.

The switch from STD to STI gets away from the word "disease," according to the American Sexual Health Association (ASHA).

"The concept of 'disease,' as in STD, suggests an obvious medical problem, usually some obvious signs or symptoms. But many common STDs have no signs or symptoms in most of the people who have them. Or they have mild signs and symptoms that can be easily overlooked," ASHA notes.

A Quick Review

Whether you use the term STD or STI is up to you. "The important take-home message is that you can use either STI or STD, depending on your preference. But don't pay any less attention to the health impacts of either one," Dr. Handsfiled said.

Prevention, diagnosis, and treatment are all critical. Talk to a provider about the screening tests you need based on your age and sexual history.

You should also feel secure enough to ask for a test if you think you need one, added Dr. Alagia. "When you catch infections early, it will make a big difference in your overall health and well-being,"