If you've had unprotected sex, even once, you could be at risk for contracting an STI, or sexually transmitted infection. There are a variety of STIs, ranging from treatable to untreatable, some of which exhibit no symptoms. In fact, many STI symptoms resemble symptoms of other common ailments. That's why it's important to get tested as soon as possible after unprotected sex.

Think you might have an STI? Here are some common symptoms for women:

  • Irregular discharge
  • Vaginal blisters
  • Painful urination
  • Lower back pain
  • Nausea
  • Fever
  • Bleeding between periods
  • Pain during intercourse
  • No symptoms

According to the CDC, CDC’s analysis suggests that there are more than 110 million STIs overall among men and women nationwide.
In fact, over 50 percent of new infections occur from people ages 12 to 24, with Chlamydia being the most common.

Learn more about some of the most prevalent STIs in America.

Chlamydia is the most commonly reported STD and can be transmitted during unprotected vaginal, oral, or anal sexual contact with an infected partner. With Chlamydia, many people experience no symptoms at all. If symptoms are present, they could include: fever, abdominal pain and unusual discharge. If left untreated, Chlamydia can lead to pelvic inflammatory disease, which could eventually cause problems with the reproductive system like infertility.

Gonorrhea is the most common bacterial STD. The symptoms of gonorrhea are vaginal and penile discharge or painful urination. As with Chlamydia, leaving Gonorrhea untreated can cause pelvis inflammatory disease, infertility and ectopic pregnancies. Gonorrhea can affect the throat, eyes, mouth and rectum, and even spread to the bloodstream and joints, causing a variety of life-threatening illnesses.

Human Papillomavirus (HPV)
HPV is the most common STI. More than 40 strands of the virus exist, and all of them can infect both men and women. Although no cure exists for HPV, most strains can be prevented through a vaccine. Regular pap smears can also prevent or detect early stages of cervical cancer caused by HPV.

Genital Herpes
Genital Herpes typically causes painful, watery skin blisters on or around the genitals or anus. However, the majority of people who carry these viruses have minimal or no symptoms. Genital Herpes cannot be cured, because the virus can be found deep in body's nerve cells. When people have a new outbreak of genital blisters, this is the time where the STI is most contagious.

HIV or the human immunodeficiency virus ,causes AIDS (acquired immunodeficiency syndrome). HIV destroys the body's immune system by killing the blood cells that fight infection. Once HIV destroys these cells, the body can no longer fight off and recover from infections. This is when HIV progresses to AIDS. People who have AIDS are susceptible to even minor types of infections and certain forms of cancer. Both HIV and AIDS cannot be cured.

Syphilis is passed from person to person during vaginal, anal, or oral sex through direct contact with sores, called chancres. The first sign of syphilis is a painless genital sore that most often appears around the vagina or on the penis. Having Syphilis makes a person more likely to contract HIV, which increases the likelihood that the infection will be passed to a sexual partner. Syphilis can be cured, but if left untreated, could eventually spread to vital organs such as the brain, liver and heart.

Bacterial Vaginosis
Bacterial Vaginosis is a fairly common vaginal infection and can be cause by having multiple sexual partners. While a vagina typically has different types of safe bacteria growing in it, sometimes changes in the balance of those types of bacteria can cause issues, such as unusual smells and discharge. Having bacterial vaginosis could increase the risk of getting other STIs, as well as pelvic inflammatory disease.

Trichomoniasis is most common in young women. The parasite spreads when an infected person comes in contact with another's genitals. Although Trichomoniasis doesn't always exhibit symptoms, they can cause frequent, painful, or burning urination in men and women as well as vaginal discharge, genital soreness, redness, or itching in women. Because the infection can occur without symptoms, a person may be unaware that he or she is infected. Trichomoniasis is treatable with antibiotics.

STIs are commonly spread through bodily fluids such as vaginal fluids, semen or blood. Wearing a condom decreases the possibility of contracting some STIs, however, you can still contract herpes, HPV, syphilis, pubic lice, or scabies just from skin-to-skin contact. The only way to prevent contracting an STI is to abstain from all forms of sexual intercourse. If you think you might have an STI, it's important to seek medical assistance right away.