Complete Guide to the Most Common Sexually Transmitted Infections (STIs)

What are Sexually Transmitted Infections?

Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs) are infections or diseases that pass from one person to another person through different types of sexual contact. Many STIs do not cause symptoms or symptoms may not appear for a long time. Infection is still possible even if you or your partner do not have symptoms.

How do STIs spread?

STIs spread through oral, vaginal or anal sex with someone who is infected with the disease. Anyone who is sexually active can get an STI. “Going all the way” by vaginal or anal penetration sex is not required to get an STI. Some STIs, like herpes and human papilloma virus (HPV), are spread by skin-to-skin contact and can happen without sexual penetration.

How common are STIs?

STIs are very common, especially among younger people. According to the Centers for Disease Control (CDC), about 20 million new cases of STIs are reported each year in the United States. Approximately 10 million of these infections are in people between ages 15 and 24.

The Most Common STIs

• Bacterial vaginosis (BV) happens when bacteria that normally live in the vagina grow too much. Bacterial vaginosis is not an STI, but the bacterial overgrowth puts you at greater risk of contracting an STI.
  • How is it spread? We don’t know the cause, but unprotected sex may increase the risk of developing BV. What are the symptoms? Some people do not have symptoms. If you do, these are most common:
    • Vaginal itching
    • Thin, gray, white or green vaginal discharge
    • Foul-smelling “fishy” vaginal odor
    • Burning during urination
  • Can it be cured? Yes, with prescription antibiotics.
• Chlamydia is one of the two most common STIs in the United States and usually has no symptoms. If you’re sexually active and under the age of 25 you should get tested at least once a year.
  • How is it spread? Chlamydia is transmitted through all types of sexual contact. Anyone who is sexually active can get it.
  • What are the symptoms? Chlamydia doesn’t normally have symptoms.
  • Can it be cured? Yes, with prescription antibiotics. If not treated, chlamydia can cause permanent damage to a woman’s reproductive system. Getting pregnant later on may be difficult or impossible.
• Genital herpes is very common and does not always have symptoms; or, the symptoms are so mild, you may not know you are infected.
  • How is it spread? Genital herpes is caused by two strains: herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). You can contract one or both. HSV-1 causes cold sores on your face. However, it can be transmitted to the genital area through oral sex with an infected person. HSV-2 causes genital herpes and is transmitted by having vaginal, anal, or oral sex with someone who is infected.
  • What are the symptoms? Symptoms include blisters that turn into painful, open sores that last about a week.
  • Can it be cured? No, but medicines are available that can shorten the length of an outbreak and lessen the severity of symptoms.
• Gonorrhea is very common, especially among younger people. Gonorrhea can cause infections in the genital area, rectum and throat. Gonorrhea’s nickname is “the clap.”
  • How is it spread? You can get gonorrhea by having vaginal, anal or oral sex with someone who has gonorrhea.
  • What are the symptoms? A person infected with gonorrhea may have no symptoms, but an untreated infection may lead to serious complications. Symptoms include:
    • Painful or burning sensation when urinating
    • Discharge from the penis or vagina
    • Painful or swollen testicles
    • Vaginal bleeding between periods
    • An anal gonorrhea infection has additional symptoms
  • Can it be cured? Yes, with prescription antibiotics.
• Hepatitis causes inflammation of the liver. There are five different strains of hepatitis, but only three (HAV, HBV and HCV) are common in the United States.
  • How is it spread? 
    • HAV most often spreads when objects, food or drinks contaminated by small amounts of stool (poop) from an infected person are ingested. HAV can also spread through sex or while caring for an infected person who is ill.
    • HBV is transmitted through all forms of sex, needle sharing, syringes, or from mother to baby at birth.
    • HCV is spread primarily through injection drug use. In rare cases, HCV may spread through sex.
  • What are the symptoms? Not everyone with HBV infection develops symptoms, which varies by age. HCV is often symptomless as well. When symptoms do develop, HAV, HBV and HCV have similar symptoms, including fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, clay-colored stool (poop), joint pain and jaundice (yellowing of the skin).
  • Can it be cured? Vaccines are available to prevent Hepatitis A and B. Anyone who previously had HAV cannot be reinfected – they are immune. Hepatitis C does not have a vaccine, but is now curable with prescription medication.
• Human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) weakens a person’s immune system by destroying important immune system cells that fight disease and infection.
  • How is it spread? The most common ways HIV is spread are through sexual behaviors and needle sharing or syringe use.
  • What are the symptoms? HIV itself does not have symptoms. HIV is the virus that can develop into AIDS. If AIDS develops, an infected person’s immune system becomes so suppressed that it cannot fight off other infections, causing symptoms from those infections. The medications used to treat HIV infection may cause symptoms.
  • Can it be cured? No. However, there are antiviral medications that, when taken properly and forever, can lower the amount of virus in an infected person to undetectable levels. Though not disease-free, people with undetectable levels of the virus are also not contagious through sexual activity. There is also a medication called PrEP that, when taken correctly, reduces your chance of contracting HIV if you are at risk. PrEP is used as an additional prevention measure and is not meant to replace other safety measures, such as using a condom.
• Human papillomavirus (HPV) is one of the two most common STIs in the United States. HPV is so common that almost every person who is sexually active will get HPV at some time in their life. There are many different strains of HPV.
  • How is it spread? Anyone who is sexually active can get HPV, even if you have had sex with only one person. You can get HPV by having vaginal, anal or oral sex with someone who has the virus.
  • What are the symptoms? Some types of HPV can cause genital warts and different cancers. Genital warts may appear as a small bump or group of bumps in the genital area. Some people find out they have HPV when their Pap smear has an abnormal result, though they may not have any symptoms.
  • Can it be cured? No. For most people, HPV goes away on its own and does not cause any health problems. However, if you develop health problems or warts, there are treatments. There is also a vaccine that can prevent the type of HPV that causes cervical cancer.
• Pelvic inflammatory disease (PID) is an infection of a woman’s reproductive organs. PID is often caused by some STIs, such chlamydia and gonorrhea. Other infections that are not sexually transmitted can also cause PID. Complications from PID are extremely dangerous to the reproductive system and can lead to ectopic pregnancy or infertility.
  • How is it spread? PID is not contagious, so you cannot spread it to another sexual partner.
  • What are the symptoms? Symptoms may be mild to none:
    • Pain in your lower abdomen
    • Fever
    • Unusual vaginal discharge with a bad odor
    • Pain and/or bleeding when you have sex
    • Burning sensation when you urinate
    • Bleeding between periods
  • Can it be cured? Yes. If diagnosed early, PID can be treated with antibiotics. The longer PID goes untreated, the more likely irreversible complications will develop. Treatment won’t undo any damage that has already happened to your reproductive system. If you have had PID before, your chances of developing it again are higher.
• Syphilis is divided into four stages: primary, secondary, latent and tertiary. Each stage has different signs and symptoms.
  • How is it spread? Syphilis is spread by direct contact with a syphilis sore during vaginal, anal or oral sex, or from an infected mother to her unborn baby.
  • What are the symptoms? The signs and symptoms of primary and secondary syphilis may be so mild that an infected person might not notice them.
    • Primary syphilis starts when a sore or sores appear where the infection first enters the body. Sores appear on or around the penis, vagina, anus, in the rectum, on the lips or in the mouth. These sores are usually (but not always) firm, round and painless.
    • Secondary syphilis can include a fever, skin rash and swollen lymph nodes.
    • The latent stage has no signs or symptoms and may last for years.
    • Tertiary syphilis is associated with severe medical problems, affecting the heart, brain and other body organs. If untreated, syphilis may extend into the brain and the eye.
  • Can it be cured? Yes. Syphilis can be cured with specific prescription antibiotics. 
• Trichomoniasis, or “trich/trick,” is the most common curable STI. Trich is caused by infection with a parasite called Trichomonas vaginalis. Infection can increase your risk of getting or spreading other STIs, including HIV.
  • How is it spread? Trich is spread through sex from a penis to a vagina, from a vagina to a penis, or from a vagina to another vagina.
  • What are the symptoms? Most people infected with trich do not have symptoms. When symptoms are present, they can come and go.
    • Symptoms in men: Itching or irritation inside the penis; burning after urination or ejaculation; discharge from the penis; discomfort having sex.
    • Symptoms in women: Genital itching, burning, redness or soreness of the genitals; urination pain or discomfort; a change in vaginal discharge that can be clear, white, yellowish or greenish with an unusual fishy smell; discomfort having sex.
  • Can it be cured? Yes, with medication. You can get trich repeatedly though. To avoid reinfection, all sex partners should be treated with antibiotics at the same time. All partners should also wait to have sex again until everyone has been treated and any symptoms go away (usually about a week).

Preventing STIs

The only way to completely protect yourself against STIs is to not have oral, vaginal or anal sex (abstinence). If you decide to have sex, the following actions will help reduce your risk of getting an STI:

• Talk with your partner about how you both plan to prevent STIs and pregnancy
• Talk about birth control methods
• Get vaccinated. Vaccines are available for HPV, hepatitis A and hepatitis B
• Get tested for STIs before having sex – both you and your partner
• Learn how to properly use a condom
• Always use a condom with vaginal, anal or oral sex, from start to finish with a new condom for each sex act
• Be monogamous – you and your partner only have sexual contact with each other
• Avoid mixing alcohol and/or drug use with sex, which make people more likely to take risks

Getting Tested for STIs

Girls and young women may have extra needs to protect their reproductive health. Talk to your healthcare provider about regular STI testing, such as cervical cancer screening, and chlamydia and gonorrhea testing.

• Where do I go to get tested? NJFPL-supported health centers provide affordable and accessible STI testing and treatment. Finding a health center near you is easy. There is at least one in every county of New Jersey, and the services are low or no-cost.
• What can I expect at a screening? Many people don’t get screened for STIs for fear of the unknown. Will it be embarrassing? Will it be expensive? Will it hurt? The truth is, STI screenings are important and beneficial to anyone who is sexually active. STI screenings are worth the peace of mind alone, not to mention all the health benefits to be gained from early detection and treatment. Remember, doctors, nurses and other healthcare professionals are there to help, not to judge.

If you are experiencing symptoms of an STI or are sexually active and want to get tested, contact your local healthcare provider right away. Find the NJFPL-supported health center that is closest or most convenient to you and call to set up your appointment.