What are STIs?

Sexually transmitted infections (STIs) are diseases that are spread through sexual contact. If you have sex with someone who has an STI, you can get it too. STIs are among the most common diseases in the United States. About one in four Americans has an STI.

What are the dangers?

  • Chlamydia and gonorrhea can make a woman sterile so she can never have a baby.

  • Herpes can cause sores or irritation on the genitals. The sores can come back again and again.

  • Some types of human papillomavirus (HPV) cause genital warts. Other types of HPV can lead to cervical cancer in women.

  • STIs in pregnant women can cause problems with pregnancy and lead to serious, sometimes fatal, infections in the baby.

  • HIV can kill you.

How do you get STIs?

STIs can be spread through vaginal, oral, or anal sex. Some STIs can also be spread through any contact with the penis, vagina, mouth, or anus – even if you don’t have sexual intercourse. STIs can be spread from man to woman, woman to man, man to man, and woman to woman. Some STIs, such as HIV and hepatitis B and C, are also spread through sharing needles. It’s hard to tell who has an STI because many people who are infected look and feel healthy. They may not ever know they have an infection, but they can still pass the STI to you.

How do you prevent STIs?

The surest way to prevent STIs is not to have sex. There are many ways to show love and feel good without having sex.

How can I make sex safer?

  • Before you have sex, talk with your partner. Agree to use condoms. Use a condom every time you have vaginal sex, oral sex, or anal sex. Male and female condoms are now available.

  • Be prepared. Both men and women should carry condoms.

  • Don’t use lotions, creams, or Vaseline®’ with latex condoms. The oil in these products can weaken the condom. Use water-based lubricants such as K-Y Jelly®’ or Astroglide.®

  • Spermicides with N-9 are not effective in preventing STIs, including HIV. N-9 may increase your risk for infection with HIV. Using spermicides is not recommended.

  • Know that you are more likely to get an STI if you have more than one partner.

  • Get tested for STIs if you or your partner have had multiple partners.

Do STIs cause special problems in women?

Yes. Many STIs show no signs or symptoms in women. Women may be infected in places where symptoms are not easily seen. One STI, HPV, can lead to cervical cancer. Other untreated STIs can cause problem pregnancies or even prevent a woman from getting pregnant. Often a woman has no idea that she has an STI until the infection has caused lasting damage.

What are the symptoms of STIs?

Most people who have an STI have no symptoms. A test from your health care provider or local health clinic may be the only sure way to tell if you’re infected. If you do have symptoms, they may appear right away, or disappear, they disease may still be active.

Here are some signs or symptoms that may mean you have an STI:

Possible symptoms for women:

  • Sores, bumps, or blisters near your genitals, anus, or mouth

  • Burning or pain when you urinate

  • Itching, a bad smell, or unusual discharge from your vagina or anus

  • Pain in your lower belly

  • Bleeding from your vagina when you don’t have your period

Possible symptoms for men:

  • Sores, bumps, or blisters near your genitals, anus, or mouth

  • Burning or pain when you urinate

  • Drip or discharge from your penis

  • Itching, pain, or discharge from your anus

What if I think I have an STI?

Get help from your health care provider or clinic right away. Early treatment can prevent lasting damage to your body.

What about treatments?

Many STIs can be cured by taking medicine to kill the germ that causes the infection. Some STIs cannot be cured, but treatment can relieve the symptoms and may prevent damage to your body.

  • Do not have sex until treatment for all partners is finished.

  • Take ALL of the medicine you are given even if you start to feel better or symptoms go away.

  • NEVER take anyone else’s medicine or give yours to someone else.

  • Return to the clinic for more tests if you are told to do so.

  • TELL anyone you have had sex with that they may have an STI and need to be tested. Your local health department can help you with this.

  • Talk to your doctor or nurse about getting vaccinated against hepatitis B.

Some Common STIs


Estimated New Cases Each Year


14.1 million


2.9 million

Trichomoniasis ("trich")

1.1 million











Do STIs lead to AIDS?

The only STI that leads to AIDS is HIV. But having another STI can make it easier to get HIV if you come in contact with it. Some STIs cause breaks in the skin that let HIV enter the bloodstream more easily. See a health care provider for testing and treatment if you think you might have an STI.

AIDS: A special case?

AIDS is the most serious STI because it can lead to death. AIDS is caused by the HIV virus. This virus attacks the body’s immune system and leaves the person unable to fight off many kinds of infections and cancers. Over 1 million people in the United States are infected with HIV. The virus cannot be cured, but new medicines slow the damage that HIV causes to the immune system.

How do you get HIV?

HIV is passed through blood, semen, vaginal fluid, and breast milk. If infected blood, semen, or vaginal fluid gets into your body, the virus might infect you, too. Most people with AIDS became infected from having sex or sharing drug needles with a person who has HIV. The virus also can be passed from a mother to her baby during pregnancy or at birth (or through breastfeeding after birth). HIV is NOT spread through skin to skin contact.

In the past, HIV was sometimes spread to people who received a blood transfusion because the blood contained the virus. This doesn’t happen anymore because all blood supplies in the U.S. are screened for HIV. If HIV is found in the blood, that blood is not transfused.

Many people who have HIV don’t know it because they look and feel fine for many years after they become infected. This means they can pass the virus to others through sex or shared needles without knowing it.

To learn more about STIs, talk with your doctor, go to your local health department, or call:

  • American Social Health Association (ASHA) | 1.888.STD.AIDS (1.888.783.2437) | 24 hours a day, 365 days a year

  • National STI Hotline | 1.800.227.8922 | 24 hours a day, 365 days a year

  • CDC Information Service | 1.800.CDC.INFO (1.800.232.4636) | 24 hours a day, 365 days a year



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