What’s the Difference Between an STD and an STI?

You’ve probably heard both terms, STD (sexually transmitted disease) and STI (sexually transmitted infection). They are often used interchangeably, but there is an important distinction. Understanding the difference can help you make sense of your health, testing options, and treatment.

STI vs. STD: Breaking It Down

An STI refers to the presence of a virus, bacteria, or parasite in the body that was transmitted through sexual contact. You can have an infection without showing any symptoms. An STD, on the other hand, describes what happens when that infection progresses and causes symptoms or complications. In short, all STDs start as STIs, but not all STIs will develop into an STD.

Why Language Matters

Medical professionals now lean toward the term STI because it is more accurate. Many sexually transmitted infections are completely asymptomatic, meaning you can carry and transmit them without ever feeling sick. Calling them “diseases” can be misleading and sometimes discourages people from getting tested, since “disease” suggests something obvious and visible. Using “STI” also helps reduce stigma, which makes it easier to have honest conversations about sexual health.

Common Examples

Chlamydia and gonorrhea are prime examples of infections that often do not cause symptoms. Without testing, you may never know you have them, but if left untreated, they can lead to complications such as infertility. HIV begins as an infection. If it is not treated, it can progress into AIDS, which is the disease stage. Human papillomavirus (HPV) works similarly: some strains clear up on their own with no symptoms, while others can lead to genital warts or even cancer.

Why This Matters for You

Knowing the difference between an STI and an STD highlights one simple truth: you cannot rely on symptoms alone to know your status. The only way to be sure is through regular testing. Early detection means infections can be treated before they cause long-term problems, protecting both your health and your partners.

Takeaway

Think of “STI” as the infection itself and “STD” as the condition that can result if the infection causes symptoms or complications. By normalizing the use of STI and encouraging routine screening, we make it easier to catch infections early, treat them effectively, and stop them from becoming more serious.

Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. If you have questions about your health, symptoms, or risk factors, you should consult with a licensed healthcare provider.