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Sexually transmitted infections (STIs)

STIs are also called sexually transmitted diseases, or STDs. STIs are usually spread by having vaginal, oral, or anal sex. More than 9 million women in the United States are diagnosed with an STI each year.1 Women often have more serious health problems from STIs than men, including infertility.

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What is a sexually transmitted infection (STI)?

An STI is an infection passed from one person to another person through sexual contact. An infection is when a bacteria, virus, or parasite enters and grows in or on your body. STIs are also called sexually transmitted diseases, or STDs.

Some STIs can be cured and some STIs cannot be cured. For those STIs that cannot be cured, there are medicines to manage the symptoms.

Who gets STIs?

Nearly 20 million people in the United States get an STI each year.2 These infections affect women and men of all backgrounds and economic levels. But half of all new infections are among young people 15 to 24 years old.2

How do STIs affect women?

Women often have more serious health problems from STIs than men:

  • Chlamydia and gonorrhea, left untreated, raise the risk of chronic pelvic pain and life-threatening ectopic pregnancy. Chlamydia and gonorrhea also can cause infertility.
  • Untreated syphilis in pregnant women results in infant death up to 40% of the time.3
  • Women have a higher risk than men of getting an STI during unprotected vaginal sex. Unprotected anal sex puts women at even more risk for getting an STI than unprotected vaginal sex.

How do you get STIs?

STIs are spread in the following ways:

  • Having unprotected (without a condom) vaginal, oral, or anal sex with someone who has an STI. It can be difficult to tell if someone has an STI. STIs can be spread even if there are no signs or symptoms.
  • During genital touching. It is possible to get some STIs, such as syphilis and herpes, without having sex.
  • Through sexual contact between women who have sex only with other women
  • From a pregnant or breastfeeding woman to her baby

Can STIs cause health problems?

Yes. Each STI causes different health problems for women. Certain types of untreated STIs can cause or lead to:

  • Problems getting pregnant or permanent infertility
  • Problems during pregnancy and health problems for the unborn baby
  • Infection in other parts of the body
  • Organ damage
  • Certain types of cancer, such as cervical cancer
  • Death

Having certain types of STIs makes it easier for you to get HIV (another STI) if you come into contact with it.

What are the signs and symptoms of STIs?

Many STIs have only mild symptoms or no signs or symptoms at all. When women have symptoms, they may be mistaken for something else, such as a urinary tract infection or yeast infection. Get tested so that you can be treated for the correct infection.

How do I get tested for STIs?

Ask your doctor or nurse about getting tested for STIs. Your doctor or nurse can tell you what test(s) you may need and how they are done. Testing for STIs is also called STI screening.

STI testing can include:

  • Pelvic and physical exam. Your doctor looks for signs of infection, such as warts, rashes, or discharge.
  • Blood test. A nurse will draw some blood to test for an STI.
  • Urine test. You urinate (pee) into a cup. The urine is then tested for an STI.
  • Fluid or tissue sample. Your doctor or nurse uses a cotton swab to take fluid or discharge from an infected place on your body. The fluid is looked at under a microscope or sent to a lab for testing.

Find a clinic near you where you can get tested for STIs or get vaccines against hepatitis B and human papillomavirus (HPV).

Does a Pap test screen for STIs?

No. Pap testing is mainly used to look for cell changes that could be cancer or precancer. However, your doctor may test you for HPV in addition to doing the Pap test if you are older than 30.

If you want to be tested for STIs, you must ask your doctor or nurse.

Do I need to get tested for STIs?

If you are sexually active, talk to your doctor or nurse about STI testing. Which tests you will need and how often you need to get them will depend on you and your partner's sexual history.

You may feel embarrassed or that your sex life is too personal to share with your doctor or nurse. But being open and honest is the only way your doctor can help take care of you. Find out what screening tests you may need. Then talk to your doctor or nurse about what tests make sense for you.

How can I get free or low-cost STI testing?

Under the Affordable Care Act, most health insurance plans must cover the cost of STI screening or counseling at no cost to you.

For information about other services covered by the Affordable Care Act, visit HealthCare.gov.

How are STIs treated?

For some STIs, treatment may involve taking medicine by mouth or getting a shot. For other STIs that can't be cured, like herpes or HIV/AIDS, medicines can help reduce the signs and symptoms.

If I have an STI, does my partner have it too?

Maybe. If the tests show that you have an STI, your doctor might want your partner to come in for testing. Or the doctor may give you a medicine to take home for your partner.

The STI may have spread to you or your partner from a former sex partner. This is why it is important to get tested after each new sex partner. Also, if you test positive for certain STIs (HIV, syphilis, or gonorrhea), some cities and states require you (or your doctor) to tell any past or current sex partners.

Do medicines sold over the Internet prevent or treat STIs?

No. Only use medicines prescribed or suggested by your doctor.

Some drugs sold over the Internet claim to prevent or treat STIs. And some of these sites claim their medicines work better than the medicines your doctor prescribes. But in most cases this is not true, and no one knows how safe these products are or even what is in them.

Buying prescription and over-the-counter drugs on the Internet means you may not know exactly what you're getting. An illegal Internet pharmacy may try to sell you unapproved drugs, drugs with the wrong active ingredient, drugs with too much or too little of the active ingredient, or drugs with dangerous ingredients.

How can I prevent an STI?

The best way to prevent an STI is to not have vaginal, oral, or anal sex.

If you do have sex, lower your risk of getting an STI with the following steps:

  • Get vaccinated. There are vaccines to protect against HPV and hepatitis B.
  • Use condoms. Condoms are the best way to prevent STIs when you have sex. Because a man does not need to ejaculate (come) to give or get some STIs, make sure to put the condom on before the penis touches the vagina, mouth, or anus. Other methods of birth control, like birth control pills, shots, implants, or diaphragms, will not protect you from STIs.
  • Get tested. Be sure you and your partner are tested for STIs. Talk to each other about the test results before you have sex.
  • Be monogamous. Having sex with just one partner can lower your risk for STIs. After being tested for STIs, be faithful to each other. That means that you have sex only with each other and no one else.
  • Limit your number of sex partners. Your risk of getting STIs goes up with the number of partners you have.
  • Do not douche. Douching removes some of the normal bacteria in the vagina that protects you from infection. This may increase your risk of getting STIs.
  • Do not abuse alcohol or drugs. Drinking too much alcohol or using drugs increases risky behavior and may put you at risk of sexual assault and possible exposure to STIs.

The steps work best when used together. No single step can protect you from every single type of STI.

What research is being done on STIs and women?

Research on STIs is a public health priority. Research is focused on prevention, diagnosis, and treatment.

  • Researchers are looking at ways to prevent STIs with vaccines and microbicides. A microbicide is a gel or a cream that can be applied inside the vagina or anus to protect against STIs, including HIV.
  • Scientists are working on vaccines to prevent HIV and herpes infections.
  • Many women do not show any signs or have any symptoms for certain STIs, or have very mild symptoms that can be mistaken for other things. Researchers are studying the reasons why many STIs have no symptoms, which can delay diagnosis.

Learn more about current research on STIs at clinicaltrials.gov.

Did we answer your question about STIs?

For more information about STIs, call the OWH Helpline at 800-994-9662 or contact the following organizations:


  1. Centers for Disease Control and Prevention. (2013). PDF - Requires Adobe Acrobat Reader Incidence, Prevalence, and Cost of Sexually Transmitted Infections in the United States (PDF, 1.6 MB).
  2. Satterwhite, C.L., et al. (2013). Sexually transmitted infections among U.S. women and men: Prevalence and incidence estimates, 2008. Sexually Transmitted Diseases; 40(3): 187–193.
  3. Centers for Disease Control and Prevention. (2014). Syphilis – CDC Fact Sheet.

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All material contained on this page is free of copyright restrictions and may be copied, reproduced, or duplicated without permission of the Office on Women's Health in the Department of Health and Human Services. Citation of the source is appreciated.

This fact sheet was reviewed by:

Jill E. Long, M.D., M.P.H., FACOG, Commander, U.S. Public Health Service Commissioned Corps, Medical Officer, Sexually Transmitted Diseases Branch, Division of Microbiology and Infectious Diseases,National Institute of Allergy and Infectious Diseases (NIAID)


Centers for Disease Control and Prevention (CDC) staff

Content last updated: August 31, 2015.

Content last reviewed: March 25, 2014.

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