Your Go-To Guide for Understanding Sexually Transmitted Infections (STIs)

Your Go-To Guide for Understanding Sexually Transmitted Infections (STIs)

When it comes to protecting yourself from Sexually Transmitted Infections (STIs), it is important to understand how they are transmitted. But just as important as preventing the spread of STIs, understanding signs and symptoms, knowing the long-term health implications, how to get tested, and how to treat them if the need should arise are also good things to know. Luckily, I’m going to be going over all of this for you. 

First of all, STIs are caused by either a bacteria, a parasite, or a virus. Bacterial and parasitic infections, like Chlamydia, can be cured if caught and treated early. However, a viral infection, like HIV, cannot be cured, but can be managed with the right medications. This is an important distinction to make. Second, STIs are mainly transmitted via unprotected sexual contact with a person who is carrying the bacteria, parasite, or virus. This includes vaginal, oral, and anal sex but, depending on the STI, can also include skin-to-skin contact. Viruses, like HIV, can also be transmitted though the sharing of dirty needles via body piercings, tattoos, or intravenous drug use. 

Now, before I get into the details, I understand there is a lot of information in this article and it can seem overwhelming. This is why I want you to use it as your go-to guide. Print it out, cut up the sections, hang it on your wall, and refer to it often. For your convenience, I have added a short-cut at the bottom of each section called The Three T’s of STIs. This short-cut includes quick info on how the STI is 1) transmitted, 2) tested for, and 3) treated. And as a general rule, when it comes to STIs, use a condom (or dental dam) each time you engage in sexual activity, and get tested every time you have sexual contact with a new partner. 

Finally, if you have an STI or contract one in the future, I want you to know that you are not "dirty," "unclean," or even "unlovable." There are millions of people living healthy lives who are involved in fulfilling relationships even though they have or have had an STI. I know there is a lot of stigma surrounding this topic and one of my goals is to help break those down. 

Alright, let’s get started:



Chlamydia, medically known as Chlamydia trachomatis, is the most common STI in the United States. So common, in fact, that in 2015, there were 1,526,658 new infections in the US, with most new infections occurring in people ages 15-24. In female-bodied people, Chlamydia can present as unusual discharge, burning/tingling during urination, lower abdominal pain, pain during sex, or bleeding between periods. In male-bodied people, Chlamydia can present as penile discharge, burning/tingling during urination, or pain and swelling of the testicles. 

It is very important to note that Chlamydia often goes undetected, particularly in female-bodied people because it can be asymptomatic (shows no symptoms). If left untreated, Chlamydia can turn into Pelvic Inflammatory Disease (PID). PID can cause the inflammation of the reproductive organs or can even block the fallopian tubes in female-bodied people. This can lead to chronic pelvic pain, ectopic pregnancy, or even infertility - all of which come with their own set of complications. 

The Three T’s of Chlamydia:

Transmission: Chlamydia is a bacteria that is transmitted via vaginal, oral, or anal sex

Testing: Give a urine sample 

Treatment: Curable through the use of antibiotics




Gonorrhea, medically known as Neisseria gonorrhoeae, is the second most common STI. In 2015, there were 395,216 new infections in the US, with most infections occurring in people ages 15-24 years of age. In female-bodied people, Gonorrhea can present as unusual discharge, burning/tingling during urination, or bleeding between periods. In male-bodied people, Gonorrhea can present as penile discharge or burning/tingling during urination. 

As with Chlamydia, it is important to note that Gonorrhea can also go undetected in female-bodied people because it can also be asymptomatic. And if left untreated, Gonorrhea can also turn into Pelvic Inflammatory Disease (PID) - see above.

The Three T’s of Gonorrhea:

Transmission: Gonorrhea is a bacteria that is transmitted via vaginal, oral, or anal sex

Testing: Give a urine sample 

Treatment: Curable through the use of antibiotics



Herpes Simplex Virus

Herpes Simplex Virus (HSV) is one of the most prevalent STIs in the United States because is comes in two highly spreadable forms. HSV-1 presents with cold sores on or around the mouth whereas HSV-2 presents as cold-sore like blisters on the penis, vulva, or anus. Although it is difficult to state an exact statistic when it comes to Herpes infections because many people do not seek medical treatment, we do know that in 2014, over 300,000 people presented with HSV-2, many between the ages of 14-49. 

While some people experience chronic Herpes breakouts, it is possible to be infected and not show any symptoms until years later, if at all. And even though you are not experiencing an active breakout, you are still able to pass the virus to others. This is what makes the Herpes Simplex Virus so prevalent. It is also important to note that if you have HSV-1 (cold sores) and are experiencing a breakout, you can transfer it to your partners genitals during oral sex. While the Herpes Simplex Virus can be accompanied by painful or embarrassing outbreaks, it is relatively harmless to your long-term health. However, having HSV while pregnant can cause complications for a newborn and precautionary measures must be taken to avoid transmission.

The Three T’s of Herpes Simplex Virus:

Transmission: Herpes is a virus that is transmitted via vaginal, oral, anal sex, or any physical contact with a herpes sore

Testing: A swab of the sore

Treatment: Not curable, but can be managed through the use of antiviral medication, healthy lifestyle, and stress reduction



Human Papilloma Virus

The Human Papilloma Virus (HPV) is another one of those tricky STIs. HPV, like Herpes Simplex Virus, is easily transferrable and many people don’t even know they have it. HPV comes in over 40 different variations. However, about 90% of people carrying the virus are asymptomatic, and just like HSV, it can be passed to your partner even if you don’t have any symptoms. According to the Centers for Disease Control, 79 million Americans are currently infected with some variation of HPV

Many who have HPV will never show symptoms. However, the most common symptom of HPV are genital warts. The biggest concern with HPV is that certain strains can lead to reproductive cancers like cervical cancer. This is why it is important for female-bodied people to receive regular cancer screenings during routine pap smears.

The Three T’s of Human Papilloma Virus:

Transmission: Human Papilloma is a virus that is transmitted via vaginal, oral, anal sex, or any skin-to-skin contact

Testing: None. Some women may be screened for strains of HPV that cause cervical cancer during routine pap smears, others only find out when they experience genital warts.

Treatment: Not curable. Some strains of HPV cause genital warts, warts can be removed with a burn or freeze treatment. There is also a vaccination available to anyone over the age of 12 which can protect you against the specific strains of HPV that cause reproductive cancers. 



Human Immunodeficiency Virus (HIV)

Human Immunodeficiency Virus (HIV) is a virus that weakens a person’s immune system, making it difficult for their body to fight off infections and disease. In 2015, there were 39,512 people diagnosed with HIV in the United States in the 13-60 age range. The most vulnerable populations for contracting HIV are Black, White, and Hispanic/Latino men who have sex with men. 

The most common signs of an HIV infection are flu-like symptoms that last for a few weeks after it has initially been contracted. It is in this early stage of infection where people are most likely to pass the virus to their sexual partners. In the next stage of HIV infection, the virus can become latent, meaning you experience no symptoms even though the virus is still active. If a person with HIV is not aware of their status or does not seek treatment, it will then progress to Acquired Immunodeficiency Syndrome (AIDS), which is the most severe stage of the infection. At this point, the body’s immune system has become so damaged it can no longer fight off bacteria or other diseases. This can lead to “opportunistic” illnesses like cancers, and eventually, death. 

The Three T’s of Human Immunodeficiency Virus:

Transmission: Human Immunodeficiency Virus is transmitted via direct contact with bodily fluids: blood, semen, vaginal fluid, or breast milk. HIV CANNOT be transmitted by hugging, closed-mouth kissing, shaking hands, sharing toilets, sharing dishes, through saliva, sweat or tears, or through the air. 

Testing: A simple blood test

Treatment: Although science is making huge strides in the treatment of HIV, it is currently not curable. However, if caught in the early stages, HIV can be successfully managed with antiviral drugs. A person treated with antivirals can live just as long as someone who does not have HIV. 




Also known as Treponema pallidum, Syphilis is a bacterial infection that causes genital or oral ulcers. In 2015, there were a total of 23,872 cases of Syphilis reported in the United States, mainly in people ages 20-29. While rates of Syphilis have been going down over the past two decades, there has been a steady increase of Syphilis in men who have sex with men. 

The initial sign of infection with Syphilis is a painless sore at the place where the bacteria entered the body: mouth, vagina, penis, or anus. After a few weeks, you may break out in a rash that you may, or may not notice. The first few signs of Syphilis will go away on their own. If you do not seek treatment, Syphilis will then enter what is known as the “latent” stage. This means it will not show any symptoms, but will hide in your system for as long as 30 years. When the bacteria “awakens” it can cause severe damage to your organs and even result in death. 

The Three T’s of Syphilis:

Transmission: Syphilis is a bacteria that is transmitted through sexual contact with a sore via vaginal, anal, or oral sex. Transmission can also occur between mother and baby during pregnancy. 

Testing: Via blood test or swabbing of an open sore

Treatment: In the early stages, Syphilis can easily be cured with a high dose of antibiotics




Also known as Trichomonas vaginalis, Trichomoniasis is a protozoan parasitic infection of the vulva, vagina, cervix, or urethra. In 2015, it was estimated that 3.7 million people in the US ages 14-60 have this particular parasite. Like many other STIs, over 70% of people with trichomoniasis do not show any symptoms. 

The most common signs of trichomoniasis for female-bodied people are itching/burning, redness/soreness in the genital region, discomfort during urination, unusual vaginal discharge, and can cause preterm labor in pregnant women. For male-bodies people they can experience itching/irritation inside the penis, burning after urination or ejaculation, or penile discharge. 

The Three T’s of Trichomoniasis:

Transmission: Trichomoniasis is transmitted via sexual contact: vaginal, oral, or anal. 

Testing: A pelvic swab for female-bodied people or a urethral swab for male-bodied people

Treatment: Curable, usually treated with antibiotics. 

. . .

Now, I know after reading through all of this, even the idea of sexual contact can seem scary. And while the thought of being exposed to STIs should be taken seriously, it is possible to protect yourself while still having a healthy, fulfilling sex life. To have safe sexual experiences it is important to:

• Use a condom each and every time you have vaginal or anal intercourse

• Use a condom or dental dam each time you have oral sex

• Properly clean and do not share sex toys with your partner(s)

• Avoid alcohol and drug use, which can lead to lowered inhibitions and poor decision making

• Limit your partners to those who share your sexual values (willingness to get tested and use condoms, monogamy, etc.)

• Abstinence is always an option, you always have the right to say no to sexual activity, even if you have engaged in it with that person before

Remember, you cannot tell if someone has an STI just by looking at them and getting tested is the ONLY way to know for sure if you have an STI. Getting tested with each new sexual partner, or at each annual physical are all great ways to be in control of your health and, should the need arise, will help you get the treatment you need. 


amy sutherland - founder

Hey all! My name is Amy Sutherland (she/her), and I have been passionate about sexual health since before I hit puberty. I've spent most of my adult life working as a writer focusing on health and wellness. More particularly, women’s reproductive health. 

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