Are STDs and STIs the same thing?

Infections that are usually spread from person to person during vaginal, anal, and oral sex can be referred to as sexually transmitted diseases (STDs) or sexually transmitted infections (STIs). Although the two terms are often used interchangeably, they do actually have slightly different meanings.

STDs is the term that many people are more familiar with, as it has been used for a lot longer to describe diseases spread through sexual contact. However, more recently there has been increased use of the term STI. This is for two reasons – to improve accuracy and to reduce stigma.

Why is the term STI more accurate?
According to the American Sexual Health Association, the term “disease” refers to a medical problem with obvious signs and symptoms (1). However, many people can be infected with an STI, but not show any symptoms whatsoever (although can still transmit the infection). So, are they really suffering from a “disease”?

As soon as a sexually transmitted bacteria or virus first enters the body and begins multiplying, it is correct to say an “infection” has occurred. But there is usually no initial impact on the normal functioning of the body so no signs of a “disease”.

In many cases, the infection can then progress to a disease, but this doesn’t occur for all STIs. For example, for chlamydia, only an estimated 10% of infected males show symptoms and 5-30% of infected females (2).

For other STIs, it may take months before any symptoms develop. For example, the average time of onset for hepatitis B symptoms is three months after exposure to the virus (3).

The stigma associated with “disease”
STIs were originally referred to as venereal diseases until this term was replaced with the more commonly used STD. Both terms include the word “disease” and both terms can make people shudder! However, using the term “infection” tends to sound less serious to many people; hence STI is not associated with as much negativity.

Reducing the stigma associated with STIs is essential, as it is important that people feel comfortable getting tested and treated for STIs. STIs are very common with an estimated 26 million new STIs in 2018 in the United States, with almost half of new STIs among youth aged 15 – 24 years (4). A lot of infected people do not show any symptoms and are unaware that they have an STI, but can still pass the infection to others. Without treatment, STIs can lead to serious health complications. However, most STIs are easy to test for and can be effectively treated.

1. STDs A to Z. American Sexual Health Association.

2. Farley TA, Cohen DA, & Elkins W (2003). Asymptomatic sexually transmitted diseases: the case for screening. Prev Med, 36 (4), 502-509.
3. Hepatitis B Questions and Answers for the Public. CDC. July 28 2020. 
4. Sexually Transmitted Infections Prevalence, Incidence, and Cost Estimates in the United States. CDC. Jan 25 2021.