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Sexually transmitted infections (STI) fact sheet

What is a sexually transmitted infection (STI)?

It is an infection passed from person to person through intimate sexual contact. STIs are also called sexually transmitted diseases, or STDs.

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How many people have STIs and who is infected?

In the United States about 19 million new infections are thought to occur each year. These infections affect men and women of all backgrounds and economic levels. But almost half of new infections are among young people ages 15 to 24. Women are also severely affected by STIs. They have more frequent and more serious health problems from STIs than men. African-American women have especially high rates of infection.

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How do you get an STI?

You can get an STI by having intimate sexual contact with someone who already has the infection. You can’t tell if a person is infected because many STIs have no symptoms. But STIs can still be passed from person to person even if there are no symptoms. STIs are spread during vaginal, anal, or oral sex or during genital touching. So it’s possible to get some STIs without having intercourse. Not all STIs are spread the same way.

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Can STIs cause health problems?

Yes. Each STI causes different health problems. But overall, untreated STIs can cause cancer, pelvic inflammatory disease, infertility, pregnancy problems, widespread infection to other parts of the body, organ damage, and even death.

Having an STI also can put you at greater risk of getting HIV. For one, not stopping risky sexual behavior can lead to infection with other STIs, including HIV. Also, infection with some STIs makes it easier for you to get HIV if you are exposed.

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What are the symptoms of STIs?

Many STIs have only mild or no symptoms at all. When symptoms do develop, they often are mistaken for something else, such as urinary tract infection or yeast infection. This is why screening for STIs is so important. The STIs listed here are among the most common or harmful to women.

Symptoms of sexually transmitted infections
Bacterial vaginosis (BV)Most women have no symptoms. Women with symptoms may have:

  • Vaginal itching
  • Pain when urinating
  • Discharge with a fishy odor
ChlamydiaMost women have no symptoms. Women with symptoms may have:

  • Abnormal vaginal discharge
  • Burning when urinating
  • Bleeding between periods
Infections that are not treated, even if there are no symptoms, can lead to:

  • Lower abdominal pain
  • Low back pain
  • Nausea
  • Fever
  • Pain during sex
Genital herpesSome people may have no symptoms. During an “outbreak,” the symptoms are clear:

  • Small red bumps, blisters, or open sores where the virus entered the body, such as on the penis, vagina, or mouth
  • Vaginal discharge
  • Fever
  • Headache
  • Muscle aches
  • Pain when urinating
  • Itching, burning, or swollen glands in genital area
  • Pain in legs, buttocks, or genital area

Symptoms may go away and then come back. Sores heal after 2 to 4 weeks.

GonorrheaSymptoms are often mild, but most women have no symptoms. If symptoms are present, they most often appear within 10 days of becoming infected. Symptoms are:

  • Pain or burning when urinating
  • Yellowish and sometimes bloody vaginal discharge
  • Bleeding between periods
  • Pain during sex
  • Heavy bleeding during periods
Infection that occurs in the throat, eye, or anus also might have symptoms in these parts of the body.
Hepatitis BSome women have no symptoms. Women with symptoms may have:

  • Low-grade fever
  • Headache and muscle aches
  • Tiredness
  • Loss of appetite
  • Upset stomach or vomiting
  • Diarrhea
  • Dark-colored urine and pale bowel movements
  • Stomach pain
  • Skin and whites of eyes turning yellow
HIV/AIDSSome women may have no symptoms for 10 years or more. About half of people with HIV get flu-like symptoms about 3 to 6 weeks after becoming infected. Symptoms people can have for months or even years before the onset of AIDS include:

  • Fevers and night sweats
  • Feeling very tired
  • Quick weight loss
  • Headache
  • Enlarged lymph nodes
  • Diarrhea, vomiting, and upset stomach
  • Mouth, genital, or anal sores
  • Dry cough
  • Rash or flaky skin
  • Short-term memory loss
Women also might have these signs of HIV:

  • Vaginal yeast infections and other vaginal infections, including STIs
  • Pelvic inflammatory disease (PID) that does not get better with treatment
  • Menstrual cycle changes
Human papillomavirus (HPV)Some women have no symptoms. Women with symptoms may have:

  • Visible warts in the genital area, including the thighs. Warts can be raised or flat, alone or in groups, small or large, and sometimes they are cauliflower-shaped.
  • Growths on the cervix and vagina that are often invisible.
Pubic lice
(sometimes called "crabs")
Symptoms include:

  • Itching in the genital area
  • Finding lice or lice eggs
SyphilisSyphilis progresses in stages. Symptoms of the primary stage are:

  • A single, painless sore appearing 10 to 90 days after infection. It can appear in the genital area, mouth, or other parts of the body. The sore goes away on its own.
If the infection is not treated, it moves to the secondary stage. This stage starts 3 to 6 weeks after the sore appears. Symptoms of the secondary stage are:

  • Skin rash with rough, red or reddish-brown spots on the hands and feet that usually does not itch and clears on its own
  • Fever
  • Sore throat and swollen glands
  • Patchy hair loss
  • Headaches and muscle aches
  • Weight loss
  • Tiredness

In the latent stage, symptoms go away, but can come back. Without treatment, the infection may or may not move to the late stage. In the late stage, symptoms are related to damage to internal organs, such as the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints. Some people may die.

(sometimes called "trich")
Many women do not have symptoms. Symptoms usually appear 5 to 28 days after exposure and can include:

  • Yellow, green, or gray vaginal discharge (often foamy) with a strong odor
  • Discomfort during sex and when urinating
  • Itching or discomfort in the genital area
  • Lower abdominal pain (rarely)

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How do you get tested for STIs?

Tests for reproductive health

Bring our Tests for Reproductive Health (PDF, 306 KB) to your next checkup.

There is no one test for all STIs. Ask your doctor about getting tested for STIs. She or he can tell you what test(s) you might need and how it is done. Testing for STIs is also called STI screening. Testing (or screening) for STIs can involve:

  • Pelvic and physical exam — Your doctor can look for signs of infection, such as warts, rashes, discharge.
  • Blood sample
  • Urine sample
  • Fluid or tissue sample —  A swab is used to collect a sample that can be looked at under a microscope or sent to a lab for testing.
Sexually transmitted infections testing site

Find an STI testing site near you.

These methods are used for many kinds of tests. So if you have a pelvic exam and Pap test, for example, don’t assume that you have been tested for STIs. Pap testing is mainly used to look for cell changes that could be cancer or precancer. Although a Pap test sample also can be used to perform tests for HPV, doing so isn’t routine. And a Pap test does not test for other STIs. If you want to be tested for STIs, including HPV, you must ask.

You can get tested for STIs at your doctor’s office or a clinic. But not all doctors offer the same tests. So it’s important to discuss your sexual health history to find out what tests you need and where you can go to get tested.

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Who needs to get tested for STIs?

If you are sexually active, talk to your doctor about STI screening. Which tests you might need and how often depend mainly on your sexual history and your partner’s. Talking to your doctor about your sex life might seem too personal to share. But being open and honest is the only way your doctor can help take care of you. Also, don’t assume you don’t need to be tested for STIs if you have sex only with women. Talk to your doctor to find out what tests make sense for you.

How are STIs treated?

The treatment depends on the type of STI. For some STIs, treatment may involve taking medicine or getting a shot. For other STIs that can’t be cured, like herpes, treatment can help to relieve the symptoms.

Only use medicines prescribed or suggested by your doctor. There are products sold over the Internet that falsely claim to prevent or treat STIs, such as herpes, chlamydia, human papillomavirus, and HIV. Some of these drugs claim to work better than the drugs your doctor will give you. But this is not true, and the safety of these products is not known.

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What can I do to keep from getting an STI?

You can lower your risk of getting an STI with the following steps. The steps work best when used together. No single strategy can protect you from every single type of STI.

  • Don’t have sex. The surest way to keep from getting any STI is to practice abstinence. This means not having vaginal, oral, or anal sex. Keep in mind that some STIs, like genital herpes, can be spread without having intercourse.
  • Be faithful. Having a sexual relationship with one partner who has been tested for STIs and is not infected is another way to lower your risk of getting infected. Be faithful to each other. This means you only have sex with each other and no one else.
  • Use condoms correctly and every time you have sex. Use condoms for all types of sexual contact, even if intercourse does not take place. Use condoms from the very start to the very end of each sex act, and with every sex partner. A male latex condom offers the best protection. You can use a male polyurethane condom if you or your partner has a latex allergy. For vaginal sex, use a male latex condom or a female condom if your partner won’t wear a condom. For anal sex, use a male latex condom. For oral sex, use a male latex condom. A dental dam might also offer some protection from some STIs.
  • Know that some methods of birth control, like birth control pills, shots, implants, or diaphragms, will not protect you from STIs. If you use one of these methods, be sure to also use a condom correctly every time you have sex.
  • Talk with your sex partner(s) about STIs and using condoms before having sex. It’s up to you to set the ground rules and to make sure you are protected.
  • Don’t assume you’re at low risk for STIs if you have sex only with women. Some common STIs are spread easily by skin-to-skin contact. Also, most women who have sex with women have had sex with men, too. So a woman can get an STI from a male partner and then pass it to a female partner.
  • Talk frankly with your doctor and your sex partner(s) about any STIs you or your partner has or has had. Talk about symptoms, such as sores or discharge. Try not to be embarrassed. Your doctor is there to help you with any and all health problems. Also, being open with your doctor and partner will help you protect your health and the health of others.
  • Have a yearly pelvic exam. Ask your doctor if you should be tested for STIs and how often you should be retested. Testing for many STIs is simple and often can be done during your checkup. The sooner an STI is found, the easier it is to treat.
  • Avoid using drugs or drinking too much alcohol. These activities may lead to risky sexual behavior, such as not wearing a condom.

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How do STIs affect pregnant women and their babies?

STIs can cause many of the same health problems in pregnant women as women who are not pregnant. But having an STI also can threaten the pregnancy and unborn baby's health. Having an STI during pregnancy can cause early labor, a woman's water to break early, and infection in the uterus after the birth.

Some STIs can be passed from a pregnant woman to the baby before and during the baby’s birth. Some STIs, like syphilis, cross the placenta and infect the baby while it is in the uterus. Other STIs, like gonorrhea, chlamydia, hepatitis B, and genital herpes, can be passed from the mother to the baby during delivery as the baby passes through the birth canal. HIV can cross the placenta during pregnancy and infect the baby during the birth process.

The harmful effects to babies may include:

Some of these problems can be prevented if the mother receives routine prenatal care, which includes screening tests for STIs starting early in pregnancy and repeated close to delivery, if needed. Other problems can be treated if the infection is found at birth.

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What can pregnant women do to prevent problems from STIs?

Pregnant women should be screened at their first prenatal visit for STIs, including:

  • Chlamydia
  • Gonorrhea
  • Hepatitis B
  • HIV
  • Syphilis

In addition, some experts recommend that women who have had a premature delivery in the past be screened and treated for bacterial vaginosis (BV) at the first prenatal visit. Even if a woman has been tested for STIs in the past, she should be tested again when she becomes pregnant.

Chlamydia, gonorrhea, syphilis, trichomoniasis, and BV can be treated and cured with antibiotics during pregnancy. Viral STIs, such as genital herpes and HIV, have no cure. But antiviral medication may be appropriate for some pregnant woman with herpes to reduce symptoms. For women who have active genital herpes lesions at the onset of labor, a cesarean delivery (C-section) can lower the risk of passing the infection to the newborn. For women who are HIV positive, taking antiviral medicines during pregnancy can lower the risk of giving HIV to the newborn to less than 2 percent. C-section is also an option for some women with HIV. Women who test negative for hepatitis B may receive the hepatitis B vaccine during pregnancy.

Pregnant women also can take steps to lower their risk of getting an STI during pregnancy.

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Do STIs affect breastfeeding?

Did you know?

If you have HIV, do not breastfeed. You can pass the virus to your baby.

Talk with your doctor, nurse, or a lactation consultant about the risk of passing the STI to your baby while breastfeeding. If you have chlamydia or gonorrhea, you can keep breastfeeding. If you have syphilis or herpes, you can keep breastfeeding as long as the sores are covered. Syphilis and herpes are spread through contact with sores and can be dangerous to your newborn. If you have sores on your nipple or areola, stop breastfeeding on that breast. Pump or hand express your milk from that breast until the sore clears. Pumping will help keep up your milk supply and prevent your breast from getting engorged or overly full. You can store your milk to give to your baby in a bottle for another feeding. But if parts of your breast pump that contact the milk also touch the sore(s) while pumping, you should throw the milk away.

If you are being treated for an STI, ask your doctor about the possible effects of the drug on your breastfeeding baby. Most treatments for STIs are safe to use while breastfeeding.

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Is there any research being done on STIs?

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

With prevention, researchers are looking at strategies such as vaccines and topical microbicides (meye-KROH-buh-syds). One large study is testing a herpes vaccine for women. Topical microbicides could play a big role in protecting women from getting STIs. But so far, they have been difficult to design. They are gels or creams that would be put into the vagina to kill or stop the STI before it could infect someone. Researchers are also looking at the reasons some people are at higher risk of STIs, and ways to lower these risks.

Early and fast diagnosis of STIs means treatment can start right away. Early treatment helps to limit the effects of an STI and keep it from spreading to others. Researchers are looking at quick, easy, and better ways to test for STIs, including vaginal swabs women can use to collect a sample for testing. They also are studying the reasons why many STIs have no symptoms, which can delay diagnosis.

Research also is underway to develop new ways to treat STIs. For instance, more and more people are becoming infected with types of gonorrhea that do not respond well to drugs. So scientists are working to develop new antibiotics to treat these drug-resistant types. An example of treatment research success is the life-prolonging effects of new drugs used to treat HIV.

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More information on sexually transmitted infections (STI)

For more information about sexually transmitted infections (STI), call womenshealth.gov at 800-994-9662 (TDD: 888-220-5446) or contact the following organizations:

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Content last updated: July 16, 2012.

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