If you’ve ever wondered why some sources use the term STD and others use STI, you’re not alone. These two acronyms are often used interchangeably, but they don’t actually mean the same thing. In fact, there’s an important distinction — one that’s shaped how doctors, public health organizations, and sexual health educators talk about testing and prevention.
Understanding the difference between STIs (sexually transmitted infections) and STDs (sexually transmitted diseases) can help you make more informed choices about your health. It also highlights why the shift toward using “STI” is more than just a language update — it reflects real changes in how we think about risk, diagnosis, and care.
STI vs STD: What’s the Difference?
The term STD has been used for decades and refers to a disease — meaning an infection that has developed clear symptoms or complications. Think of it as the later stage of an issue that’s already taken hold. On the other hand, STI refers to the presence of a virus, bacteria, or parasite that may or may not cause any noticeable symptoms.
Here’s a simple way to break it down:
- STI (Infection): A virus, bacteria, or other organism is present, but symptoms may not exist.
- STD (Disease): The infection has progressed and is now causing physical symptoms or complications.
In other words, all STDs start as STIs — but not all STIs turn into STDs.
Why the Shift Toward Using “STI”?
Medical professionals and sexual health organizations increasingly use “STI” because it more accurately describes what’s happening in most cases. The majority of people with an STI show no symptoms at all. For example, chlamydia, gonorrhea, and HPV often cause no immediate signs but can still be passed to others and cause serious long-term effects if left untreated.
Using the word “disease” implies that something is actively wrong or symptomatic, which isn’t always the case. “Infection” is a more precise term, especially when it comes to public health messaging and early detection efforts. It’s also less stigmatizing, which can encourage more people to get tested without feeling shame or fear.
How the Terms Impact Testing and Treatment
The difference between STI and STD isn’t just academic — it affects how people think about testing. Because many people associate the term “STD” with having visible symptoms or something seriously wrong, they may delay getting tested if they feel fine. The truth is, infections like herpes or HIV can be present for months or even years without any symptoms at all.
By using the term “STI,” healthcare providers can emphasize the importance of testing as a preventative measure, not just a reaction to symptoms. This helps catch more infections early, lowers transmission rates, and reduces the risk of complications down the line.
What About Public Perception?
Despite the medical shift toward “STI,” many people still search for and use the term “STD” online — and in everyday conversations. That’s why you’ll often see both terms used on websites, search engines, and even clinic brochures. It’s a bridge between common usage and updated medical terminology.
In some cases, providers may include both terms for clarity — for example, “STD testing (also known as STI testing).” This helps reduce confusion while still supporting education and awareness.
So Which Term Should You Use?
If you’re talking with a medical provider, educator, or reading reliable health resources, you’ll likely see “STI” used more often. It’s more accurate and reflects the reality that many infections go unnoticed. That said, don’t worry too much about the vocabulary. The most important thing is that you’re seeking out information, understanding your risk, and getting tested when needed.
Whether you say STD or STI, the core message stays the same — routine screening is the best way to protect yourself and your partners.
Common STIs You Should Know About
The list of STIs continues to grow, but here are some of the most common ones tested for today:
- Chlamydia
- Gonorrhea
- Syphilis
- Genital herpes (HSV-1 and HSV-2)
- HIV
- HPV (Human papillomavirus)
- Trichomoniasis
- Hepatitis B and C
- Mycoplasma genitalium
Some of these can be cured with antibiotics, while others are managed with medication and monitoring. The key to treating all of them is catching them early — and that starts with testing.
Where to Learn More
STItest.com is designed to help you make sense of sexual health, testing options, and what comes next if you test positive. If you’re not sure where to begin, visit our Compare Tests page or explore the Conditions section to learn more about specific infections.