Sexually Transmitted Infections

Sexually Transmitted Infections (STIs) are defined as an infection transmitted through sexual contact, caused by bacteria, viruses, or parasites.
Passed from one person to another through intimate physical contact – STIs are very common. In fact, CDC estimates 20 million new infections occur every year in the United States.

Sexually Transmitted Infections is the preferred term over Sexually Transmitted Diseases (STDs) for many reasons including: more accurate classification – not all infections are diseases, decreased stigmatization – encouraging patients to seek out treatment, and to act as a reminder that STIs are contagious and can be spread easily. However, STI and STD are often used interchangeably.

Sexually Transmitted Infections
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What is an STI?

There are more than 30 different sexually transmissible bacteria, viruses, and parasites. However, the most common STIs are gonorrhea, chlamydia, syphilis, trichomoniasis, herpes, human papillomavirus (HPV), and Human Immunodeficiency Virus (HIV). The majority of STIs present without symptoms, but STIs can have serious consequences. For example, some STIs can increase the risk of HIV acquisition by more than three times. HPV infection causes 530,000 cases of cervical cancer each year. Other STIs such as gonorrhea and chlamydia cause pelvic inflammatory disease and can result in adverse pregnancy outcomes or infertility.


It is often difficult to determine whether symptoms are a result of an STI versus a urinary tract infection (UTI), which is why you should always consult a medical provider if you are having any symptoms that would lead you to believe you have either condition.

The prevalence of STIs is a significant public health concern. 40% of female adolescents aged 14-19, that reported ever having had sex, have either HPV, Chlamydia, Trichomoniasis, or herpes simplex virus type 2. Statistics show the most drastic rates of infection within the population of 15-24 year olds, but STIs are present across all age groups. It is estimated that each year roughly 500 million people are infected with one of four STIs: chlamydia, gonorrhea, syphilis and trichomoniasis.

How are STIs transmitted?

STIs are transmitted through oral sex, anal or vaginal intercourse, genital touching, saliva, or contact with infected blood. Transmission of an STI through shared usage of a toilet, clothes, or towels is highly unlikely to occur as the bacteria or viruses that cause STIs need a living “host” to be able to survive and multiply.

Signs and Symptoms of an STI

Discharge: One of the hallmark symptoms of gonorrhea, chlamydia, trichomoniasis, bacterial vaginosis, and candidiasis is penile/vaginal discharge. Discharge can be clear, white, yellowish, or green.

Pain: Other common symptoms of STIs include painful urination, pain during intercourse, painful bowel movements, testicular pain, or in some cases abdominal pain/cramping.

Itching: Vaginal itching or irritation, anal itching, as well as itching or irritation inside the penis are common side effects or symptoms of a Sexually Transmitted Infection.

Smell: Strong odors are often associated with sexually transmitted infections as well.


Many STIs will have no signs or symptoms, and are classified as asymptomatic infections. However, even if you are asymptomatic you may still pass the infection on to partners.

Most Common STIs for Women and Men

Below you will find an overview of the most common STIs along with corresponding symptoms and information on the infection. However, a medical provider should always be consulted prior to making any self-diagnoses, as some STIs can be life threatening if not treated appropriately.


Chlamydia is an easily cured STI, however if left untreated, chlamydia can have serious side effects including decreasing a woman’s ability to get pregnant. Chlamydia is the most frequently reported bacterial sexually transmitted infection in the United States. Most infections are asymptomatic and lack any abnormal physical exam findings, with only 10-30% of infections displaying symptoms.

Women with a chlamydial infection may show any of the following symptoms:

  • Vaginal discharge

  • Vaginal bleeding

  • Painful urination

  • Urinary frequency

  • Pelvic Pain/Cervical Motion Tenderness (in more serious cases)


Men with a chlamydial infection may show any of the following symptoms:

  • Penile discharge

  • Urethral itching

  • Testicular pain/swelling (in more serious cases)



Gonorrhea is a sexually transmitted infection of the mucous membranes of the reproductive tract. It is transmitted through sexual contact and ejaculation does not have to occur to spread gonorrhea between partners. Gonorrhea is very common and affects young people age 15-24 more than any other age group. Many infected with gonorrhea are asymptomatic or have mild symptoms that are mistaken for a urinary tract infection.

Women with a gonorrhea infection may show any of the following symptoms:

  • Painful urination

  • Increased vaginal discharge

  • Spotting between periods


Men with a gonorrhea infection may show any of the following symptoms, typically within 14 days, following the initial infection:

  • Painful urination

  • White, yellow, or green urethral discharge

  • Occasionally testicular pain(though this typically signifies epididymitis as a result of the infection)


Gonorrhea and Chlamydia are two STIs that affect a disproportionately higher number of 15-24-year-olds than any other age group.


Trichomoniasis, also often referred to as “trich,” is a sexually transmitted infection that affects the lower genital tract in women (the vulva, urethra, or vagina) and the urethra in men. If left untreated, a trichomoniasis infection can last for years. Nearly 70% of infected persons do not show any symptoms when infected with Trichomoniasis, and the remaining 30% that show symptoms range from mild irritation to severe inflammation. Symptoms typically appear within five to thirty days of the initial infection and can make intercourse painful or unpleasant.

Women with a trichomoniasis infection may show any of the following symptoms:

  • Itching/burning/redness/soreness of the genitals

  • Uncomfortable urination

  • Thin, pungent-smelling discharge that is clear, white, yellow, or greenish


Men with a trichomoniasis infection may show any of the following symptoms:

  • Itching or irritation inside penis

  • Burning following urination or ejaculation

  • Penile discharge



Herpes is a common sexually transmitted disease that can be spread even without signs of the disease. There are two types of herpes simplex viruses, HSV-1 and HSV-2. The primary difference between the two different types is the location where they prefer to establish latency in the body, or their “site of preference.” HSV-1 typically results in cold sores or sores around the mouth/face region, whereas HSV-2 is typically the cause for outbreaks in the genital region. The virus, whether it is HSV-1 or HSV-2, will be present in the host permanently as there is no cure for herpes. Nearly one out of every six people aged 14-49 have genital herpes. Most people with the herpes virus do not know that they have it and may be unknowingly spreading the infection.

Both men and women infected with the herpes virus will usually show symptoms of one or more blisters on or around the genitals, rectum, or mouth. These blisters break and leave painful sores that take up to several weeks to heal. This is where the phrase “having an outbreak” comes from. During the first infection of herpes there may be some accompanying flu-like symptoms. Outbreaks are more common during the first year of infection, and typically lessen as years go by. There is currently no cure for herpes, but there are medications that can be prescribed by a physician or healthcare practitioner to treat the symptoms and reduce the severity of outbreaks.


Syphilis can cause long term complications and serious harm if it is not adequately treated, but is an easily cured disease when it is in its early stages. Symptoms typically appear after 21 days but symptoms can appear between 10-90 days after the initial infection. The stages of syphilis are outlined below.

Primary Stage

The first symptom of syphilis is a small, round, firm ulcer that is called a chancre. Chancres typically appear at the site of infection and are usually painless, but they are highly contagious. Chancres will last for 3-6 weeks until they will heal (whether or not you receive treatment.) However, if an infected individual does not receive treatment, the disease will progress onto the secondary stage.

Secondary Stage

The hallmark sign of the second stage of syphilis is the skin rash/mucous membrane lesions. Rashes will typically appear around the affected region and on the feet and palms of the patient’s hands. The rash is typically not itchy and may appear as rough with red and brown spots. Other symptoms besides the skin rash may include fever, swollen lymph nodes, sore throat, patchy hair loss, and various other seemingly unrelated symptoms. Once again the symptoms of secondary syphilis will resolve without treatment. However, if an infected individual does not receive adequate treatment in this stage, the disease will progress onto the latent and possibly late stage of the infection. This stage typically lasts 2-12 weeks and recurrences of this stage can continue for one to two years.

Latent and Late Stage

Latent syphilis is also known as the “hidden” stage of syphilis that usually begins around one year after the initial infection. It is referred to as the hidden stage because the bacteria is still inside the body, but the patient will not exhibit any symptoms of infection. If treatment is not received during the early stages, the patient may develop the next stage of the disease, Late Stage Syphilis. This is a very serious stage that leads to severe symptoms such as damage to the heart, eyes, brain, nervous system, and even death.


Syphilis is a STI that affects men more often than women, particularly with men who have intercourse with men.

Syphilis is a serious disease that needs to be treated immediately if you believe you may have been exposed to it.

Human Papillomavirus

Also known as HPV, human papillomavirus, is the most commonly transmitted STI. Anyone who is sexually active can get HPV and almost all adults get some form of HPV during their lifetime. There are various strains of HPV that can range in severity from having no side effects to causing cancer. There are vaccines that offer a safe way to prevent these health problems from happening, you may speak with a health care provider about being vaccinated.

Symptoms of HPV typically begin with genital warts as a small bump or group of bumps in the genital area. They may be big or small, flat or raised, or arranged in a pattern. Genital warts can be treated by a medical provider. Cervical precancer, a possible side effect of HPV infection, can be treated as well, which is why regular check ups and screenings are advised for women aged 21 to 65.


Human Immunodeficiency Virus, more commonly referred to as HIV, is a virus that can lead to acquired immunodeficiency syndrome, or AIDS. HIV cannot be cured and once you are infected with HIV, you will have the virus for the rest of your life. However, with new advances in treatment options, HIV can be controlled and can dramatically prolong the lives of people infected with HIV, while also decreasing the chance of spreading the infection to others. HIV attacks the host’s immune system by targeting CD4 cells, or T cells and eventually the body can no longer fight off infections or disease. HIV is transmitted through contact with blood, semen, vaginal fluids, or breast milk of someone who is infected.

Some people report having flu-like symptoms 2-4 weeks following exposure to HIV such as: fever, enlarged lymph nodes, sore throat, or a rash lasting anywhere from a couple of days to several weeks. Speak with a medical provider if you are concerned that you may have been infected with HIV. The only way to be sure whether or not you have been infected with HIV is to be tested, as many people with HIV do not have any symptoms at all until years after infection.

How to Prevent STIs

No method is 100% effective at preventing the spread of STIs aside from abstaining from all types of sexual contact with a partner. If you are sexually active, it is imperative that you get regular STI screenings, as this is the only way to be sure whether or not you have contracted an STI. That being said, there are methods to help prevent the spread of STIs. The most effective method to prevent STI transmission is the use of latex condoms or dental dams in all sexual contact (vaginal, oral, or anal sex.) Use a new condom or dental dam for each sex act, and never use an oil-based lubricant such as petroleum jelly while using a condom. Another way to avoid STIs is to stay in a long-term mutually monogamous relationship with a partner who is free of any STIs. Avoid any sexual acts with new partners until you have both been tested for STIs. Vaccinations are also available to act as preventative measures for certain infections such as HPV and hepatitis.

Treatment for Sexually Transmitted Infections

STIs are treated in a variety of different ways, with a variety of different medications. Some infections require a single course of antibiotics; others require combined therapies or antiviral medications. Most STIs are either curable or symptoms are manageable at least. Speak with a medical provider to further explore your options.

When to Call a Doctor

If you believe that you are having any of the symptoms of a sexually transmitted infection, it is strongly recommended that you speak with a medical provider. Symptoms will likely not resolve without specific treatment or medication regimen that only a physician or healthcare provider can prescribe.


Take our quick quiz to find out if you could have a STI:

Quiz: Do you have a STI?

This page offers general health information to facilitate discussion with your telehealth provider. You must not rely on the information on our website as an alternative to medical advice from your doctor or other professional healthcare provider.

If this is a medical emergency, please call 911. For mental health emergencies, call 988.

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