Mayo Clinic Health Library

Sexually transmitted diseases (STDs)

Updated: 02-23-2013

Definition

Sexually transmitted diseases (STDs), or sexually transmitted infections (STIs), are generally acquired by sexual contact. The organisms that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids.

Some such infections can also be transmitted nonsexually, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

It's possible to contract sexually transmitted diseases from people who seem perfectly healthy — people who, in fact, aren't even aware of being infected. Many STDs cause no symptoms in some people, which is one of the reasons experts prefer the term "sexually transmitted infections" to "sexually transmitted diseases."

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Symptoms

Sexually transmitted infections (STIs) have a range of signs and symptoms. That's why they may go unnoticed until complications occur or a partner is diagnosed. Signs and symptoms that might indicate an STI include:

  • Sores or bumps on the genitals or in the oral or rectal area
  • Painful or burning urination
  • Discharge from the penis
  • Vaginal discharge
  • Unusual vaginal bleeding
  • Sore, swollen lymph nodes, particularly in the groin but sometimes more widespread
  • Lower abdominal pain
  • Rash over the trunk, hands or feet

Signs and symptoms may appear a few days to years after exposure, depending on the organism. They may resolve in a few weeks, even without treatment, but progression with later complications — or recurrence — sometimes occurs.

When to see a doctor
See a doctor immediately if:

  • You are sexually active and you believe you've been exposed to an STI
  • You have signs and symptoms of an STI

Make an appointment with a doctor for STI counseling and, if appropriate, screening tests:

  • When you consider becoming sexually active, or when you're 21 — whichever comes first
  • Before you start having sex with a new partner
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Causes

Sexually transmitted infections can be caused by:

  • Bacteria (gonorrhea, syphilis, chlamydia)
  • Parasites (trichomoniasis)
  • Viruses (human papillomavirus, genital herpes, HIV)

Sexual activity plays a role in spreading many other infectious agents, although it's possible to be infected without sexual contact. Examples include the hepatitis A, B and C viruses, shigella, cryptosporidium and Giardia lamblia.

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Risk factors

Anyone who is sexually active risks exposure to a sexually transmitted infection to some degree. Factors that may increase that risk include:

  • Having unprotected sex. Vaginal or anal penetration by an infected partner who is not wearing a latex condom transmits some diseases with particular efficiency. Without a condom, a man who has gonorrhea has a 70 to 80 percent chance of infecting his female partner in a single act of vaginal intercourse. Improper or inconsistent use of condoms can also increase your risk. Oral sex is less risky but may still transmit infection without a latex condom or dental dam. Dental dams — thin, square pieces of rubber made with latex or silicone — prevent skin-to-skin contact.
  • Having sexual contact with multiple partners. The more people you have sexual contact with, the greater your overall exposure risks. This is true for concurrent partners as well as monogamous consecutive relationships.
  • Having a history of STIs. Being infected with one STI makes it much easier for another STI to take hold. If you're infected with herpes, syphilis, gonorrhea or chlamydia and you have unprotected sex with an HIV-positive partner, you're more likely to contract HIV. Also, it's possible to be reinfected by the same infected partner if he or she isn't also treated.
  • Abusing alcohol or using recreational drugs. Substance abuse can inhibit your judgment, making you more willing to participate in risky behaviors.
  • Injecting drugs. Needle sharing spreads many serious infections, including HIV, hepatitis B and hepatitis C. If you acquire HIV by injecting drugs, you can transmit it sexually.
  • Being an adolescent female. In adolescent girls, the immature cervix is made up of constantly changing cells. These unstable cells make the adolescent female cervix more vulnerable to certain sexually transmitted organisms.

According to a surveillance report from the Centers for Disease Control and Prevention, sexually transmitted infections are more common among certain groups, such as young people, men who have sex with men, and minority communities. The theory is that potential sex partners often belong to social networks made up of people of similar age, location and background. Within these overlapping networks, couples regularly form, split up and find new partners. If one STI is making its way through such a network, there's a good chance that others are, too.

Transmission from mother to infant
Certain STIs such as gonorrhea, chlamydia, HIV and syphilis can be passed from an infected mother to her child during pregnancy or delivery. STIs in infants can cause serious problems and may be fatal. All pregnant women should be screened for these infections and treated.

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Preparing for your appointment

Not many people feel comfortable sharing the details of their sexual experiences, but the doctor's office is one place where such information is essential to appropriate care.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, ask if there's anything you need to do in advance.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Make a list of all medications, as well as any vitamins or supplements, that you're taking.
  • Write down questions to ask your doctor.

Some basic questions to ask your doctor include:

  • What's the medical name of the infection or infections I have?
  • How, exactly, is it transmitted?
  • Will it keep me from having children?
  • If I get pregnant, could I give it to my baby?
  • Is it possible to catch this again?
  • Could I have caught this from someone I had sex with only once?
  • Could I give this to someone by having sex with that person just once?
  • How long have I had it?
  • I have these other health conditions. How can I best manage them together?
  • Should I abstain from sexual activity while being treated?
  • Does my partner have to go to a doctor to be treated?

What to expect from your doctor
Giving your doctor a complete report of your symptoms and sexual history will help your doctor determine how to best care for you. Here are some of the things you may be asked:

  • Do you think you might have a sexually transmitted infection? If so, why?
  • Are you sexually active with men, women or both?
  • Do you currently have one sex partner or more than one?
  • How long have you been with your current partner or partners?
  • Have you ever injected yourself with drugs?
  • Have you ever had sex with someone who has injected drugs?
  • What do you do to protect yourself from STIs?
  • What do you do to prevent pregnancy?
  • Has a doctor or nurse ever told you that you have chlamydia, herpes, gonorrhea, syphilis or HIV?
  • Have you ever been treated for a genital discharge, genital sores, painful urination or an infection of your sex organs?
  • How many sex partners have you had in the past year?
  • How many people have you had sex with in the past two months?
  • When was your most recent sexual encounter?
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Tests and diagnosis

If your sexual history and current signs and symptoms suggest that you have an STI, laboratory tests can identify the cause and detect coinfections you might also have contracted.

  • Blood tests. Blood tests can confirm the diagnosis of HIV or later stages of syphilis.
  • Urine samples. Some STIs can be confirmed with a urine sample.
  • Fluid samples. If you have active genital sores, testing fluid and samples from the sores may be done to diagnose the type of infection. Laboratory tests of material from a genital sore or discharge are used to diagnose the most common bacterial and some viral STIs at an early stage.

Screening
Testing for a disease in someone who doesn't have symptoms is called screening. Most of the time, STI screening is not a routine part of health care, but there are exceptions:

  • Everyone. The one STI screening test suggested for everyone ages 13 to 64 is a blood or saliva test for human immunodeficiency virus (HIV), the virus that causes AIDS. Most health care settings in the United States offer a rapid HIV test with same-day results.
  • Pregnant women. Screening for HIV, hepatitis B, chlamydia and syphilis generally takes place at the first prenatal visit for all pregnant women. Gonorrhea and hepatitis C screening tests are recommended at least once during pregnancy for women at high risk of these infections.
  • Women age 21 and older. The Pap test screens for cervical abnormalities, including inflammation, precancerous changes and cancer, which is often caused by certain strains of human papillomavirus (HPV). Experts recommend that, starting at age 21, women should have a Pap test at least every three years. Some experts also advise that women who start having sex before age 21 should have a Pap test within three years of first intercourse.
  • Women under age 25 who are sexually active. All sexually active women under age 25 should be tested for chlamydia infection. The chlamydia test uses a sample of urine or vaginal fluid you can collect yourself. Some experts recommend repeating the chlamydia test three months after you've had a positive test and been treated. The second test is needed to confirm that the infection is cured, as reinfection by an untreated or undertreated partner is common. A bout of chlamydia doesn't protect you from future exposures. You can catch the infection again and again, so you should get retested if you have a new partner. Screening for gonorrhea is also recommended in sexually active women under age 25.
  • Men who have sex with men. Compared with other groups, men who have sex with men run a higher risk of acquiring STIs. Many public health groups recommend annual or more frequent STI screening for these men. Regular tests for HIV, syphilis, chlamydia and gonorrhea are particularly important. Evaluation for herpes and hepatitis B also may be recommended.
  • People with HIV. If you have HIV, it dramatically raises your risk of catching other STIs. Experts recommend frequent syphilis, gonorrhea, chlamydia and herpes tests for people with HIV. Women with HIV may develop aggressive cervical cancer, so they should have Pap tests twice a year to screen for HPV. Some experts also recommend regular HPV screening of HIV-infected men who risk anal cancer from HPV contracted anally.
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Complications

Prompt treatment can help prevent the complications of some STIs. Since many people in the early stages of an STI experience no symptoms, screening for STIs is especially important in preventing complications.

Possible complications include:

  • Sores or bumps anywhere on the body
  • Recurrent genital sores
  • Generalized skin rash
  • Pain during intercourse
  • Scrotal pain, redness and swelling
  • Pelvic pain
  • Groin abscess
  • Eye inflammation
  • Arthritis
  • Pelvic inflammatory disease
  • Infertility
  • Cervical cancer
  • Other cancers, including HIV-associated lymphoma and HPV-associated rectal and anal cancers
  • Opportunistic infections occurring in advanced HIV
  • Maternal-fetal transmission, which causes severe birth defects
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Treatments and drugs

STIs caused by bacteria are generally easier to treat. Viral infections can be managed but not always cured. If you're pregnant and have an STI, prompt treatment can prevent or reduce the risk of infection of your baby. Treatment usually consists of one of the following, depending on the infection.

  • Antibiotics. Antibiotics, often in a single dose, can cure many sexually transmitted bacterial and parasitic infections, including gonorrhea, syphilis, chlamydia and trichomoniasis. Typically, you'll be treated for gonorrhea and chlamydia at the same time because the two infections often appear together.

    Once you start antibiotic treatment, it's crucial to follow through. If you don't think you'll be able to take medication as prescribed, tell your doctor. A shorter, simpler treatment regimen may be available. In addition, it's important to abstain from sex until you've completed treatment and any sores have healed.

  • Antiviral drugs. You'll have fewer herpes recurrences if you take daily suppressive therapy with a prescription antiviral drug, but you can still give your partner herpes at any time.

    Antiviral drugs can keep HIV infection in check for many years, although the virus persists and can still be transmitted. The sooner you start treatment, the more effective it is. Once you start treatment — if you take your medications exactly as directed — it's possible to lower your virus count to nearly undetectable levels.

Partner notification and preventive treatment
If tests show that you have an STI, your sex partners — including your current partners and any other partners you've had over the last three months to one year — need to be informed so that they can get tested and treated if infected. Each state has different requirements but most mandate that certain STIs be reported to the local or state health department. Public health departments frequently employ trained disease intervention specialists, who can help with partner notification and treatment referrals.

Official, confidential partner notification effectively limits the spread of STIs, particularly syphilis and HIV. The practice also steers those at risk toward appropriate counseling and treatment. And since you can contract some STIs more than once, partner notification reduces your risk of getting reinfected.

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Prevention

There are several ways to avoid or reduce your risk of sexually transmitted infections.

  • Abstain. The most effective way to avoid STIs is to abstain from sex.
  • Stay with 1 uninfected partner. Another reliable way of avoiding STIs is to stay in a long-term mutually monogamous relationship with a partner who isn't infected.
  • Get vaccinated. Getting vaccinated early, before sexual exposure, is also effective in preventing certain types of STIs. Vaccines are available to prevent two viral STIs that can cause cancer — human papillomavirus (HPV), hepatitis A and hepatitis B. The Centers for Disease Control and Prevention (CDC) recommends the HPV vaccine for girls and boys ages 11 and 12. If not fully vaccinated at ages 11 and 12, the CDC recommends that girls and women through age 26 and boys and men through age 26 receive the vaccine. The hepatitis B vaccine is usually given to newborns.
  • Wait and verify. Avoid vaginal and anal intercourse with new partners until you have both been tested for STIs. Oral sex is less risky, but use a latex condom or dental dam — a thin, square piece of rubber made with latex or silicone — to prevent direct contact between the oral and genital mucous membranes. Keep in mind that human papillomavirus (HPV) screening isn't available for men, and no good screening test exists for genital herpes, so you may not be aware you're infected until you have symptoms. It's also possible to be infected with an STI yet still test negative.
  • Use condoms and dental dams consistently and correctly. Use a new latex condom or dental dam for each sex act, whether oral, vaginal or anal. Never use an oil-based lubricant, such as petroleum jelly, with a latex condom or dental dam. Keep in mind that while condoms reduce your risk of exposure to most STIs, they provide a lesser degree of protection for STIs involving exposed genital sores, such as human papillomavirus (HPV) or herpes. Also, nonbarrier forms of contraception, such as oral contraceptives or intrauterine devices, don't protect against STIs.
  • Don't drink alcohol excessively or use drugs. If you're under the influence, you're more likely to take sexual risks.
  • Avoid anonymous, casual sex. Don't look for sex partners online or in bars or other pickup places. Not knowing your sex partner well increases your risk of possible exposure to an STI.
  • Communicate. Before any serious sexual contact, communicate with your partner about practicing safer sex. Reach an explicit agreement about what activities will and won't be OK.
  • Teach your child. Becoming sexually active at a young age tends to increase a person's number of overall partners and, as a result, his or her risk of STIs. Biologically, young girls are more susceptible to infection. While you can't control your teen or preteen's actions, you can help your child understand the risks of sexual activity and that it's OK to wait to have sex.
  • Consider male circumcision. There's evidence that male circumcision can help reduce a man's risk of acquiring HIV from an infected woman (heterosexual transmission) by 50 to 60 percent. Male circumcision may also help prevent transmission of genital HPV and genital herpes.
  • Consider the drug Truvada. In July 2012, the Food and Drug Administration (FDA) approved the use of the drug Truvada (a fixed dose combination of emtricitabine/tenofovir disoproxil fumarate) to reduce the risk of sexually transmitted HIV infection in those who are at high risk. Truvada is also used as an HIV treatment along with other medications.

    When used to help prevent HIV infection, Truvada is only appropriate if your doctor is certain you don't already have an HIV or hepatitis B infection. The drug must also be taken daily, exactly as prescribed. And it should only be used along with other prevention strategies such as condom use every time you have sex.

    Truvada isn't for everyone. If you're interested in Truvada, talk with your doctor about the potential risks and benefits and whether it's right for you.

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Coping and support

It's traumatic to find out you have an STI. You might be angry if you feel you've been betrayed, or ashamed if there's a chance you infected others. At worst, an STI can cause chronic illness and death, even with the best care in the world. Between those extremes is a host of other potential losses — trust between partners, plans to have children, and the joyful embrace of your sexuality and its expression.

Here's how you can cope:

  • Put blame on hold. Don't jump to the conclusion that your partner has been unfaithful to you. One (or both) of you may have been infected by a past partner.
  • Be candid with health care workers. Their job is not to judge you, but to stop STIs from spreading. Anything you tell them remains confidential.
  • Contact your health department. Although they may not have the staff and funds to offer comprehensive services, local health departments maintain STI programs that provide confidential testing, treatment and partner services.
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