STI vs STD: Is There A Difference?

If you’re researching sexually transmitted diseases, you may be confused by the use of different terminology.

For decades, STD was the go-to term for sexually transmitted diseases and infections. Now, some doctors are calling them STIs.

Technically, there is a difference between the two.

What is the Difference between an STI and an STD?


The terms STD and STI are often used interchangeably, but there is a key difference between the two that you should understand. After all, infections and diseases are two different things.

What is an STD?

STD stands for sexually transmitted disease, and it’s the most common blanket term used for medical infections transmitted through and associated with sexual contact.

Most STDs can be transmitted through vaginal, oral or anal sex.

Not everyone who becomes infected will show signs or symptoms of a disease. Infections don’t always progress into a disease. That’s why doctors developed the STI term.

What is an STI?

STI stands for sexually transmitted infection. Many doctors will now use the term STI instead of STD because infections don’t always develop into disease.

The term is meant to clarify the difference between illnesses that develop into diseases and those that remain infections or are in the infection stage.

A Real World Example

Here’s an example to illustrate the difference between STDs and STIs:

A woman contracts HPV (human papillomavirus). She has no symptoms, but she carries the virus. At this point, she has an STI. But if her HPV develops into cervical cancer, she then has an STD. Cancer is classified as a disease.


What’s the Difference between an Infection and a Disease?

How can you tell whether it’s an infection or a disease?

Infection is typically the first stage in a disease. Bacteria, microbes or viruses enter the body and they begin multiplying. At this point, the person typically doesn’t experience any symptoms.

Once signs and symptoms start appearing, the infection progresses into a disease. At this stage, the disease is disrupting normal body function.

Medically speaking, all STIs that progress into a disease are considered STDs, and all STDs start out as STIs.

There are two main types of infections that are transmitted through sexual contact: viral and bacterial.

Viral STIs might include:

  • Herpes
  • HIV
  • Hepatitis

Bacterial STIs might include:

  • Chlamydia
  • Syphilis
  • Gonorrhea

Doctors prefer the term STI over STD because it doesn’t have the same negative stigma attached to it.

Because STIs typically don’t present any symptoms, it’s important to get tested. In most cases, STIs can be cured with antibiotics. If you have an STI and you don’t get treatment, you can spread the infection to others – even if you don’t have any symptoms.

Preventing STDs and STIs

STDs and STIs may technically be different – although the terms are still used interchangeably – but they can be prevented the same way: safe sex.

Condoms can help prevent most STIs and pregnancy. Birth control can only help prevent pregnancy – offering no protection against infections.