Sexually transmitted diseases (STDs)

Date Updated: 09/21/2021

Overview

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

Sometimes these infections can be transmitted nonsexually, such as from mothers to their infants during pregnancy or childbirth, or through blood transfusions or shared needles.

STIs don't always cause symptoms. It's possible to contract sexually transmitted infections from people who seem perfectly healthy and may not even know they have an infection.

Symptoms

STDs or STIs can have a range of signs and symptoms, including no 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
Unusual or odorous vaginal discharge
Unusual vaginal bleeding
Pain during sex
Sore, swollen lymph nodes, particularly in the groin but sometimes more widespread
Lower abdominal pain
Fever
Rash over the trunk, hands or feet

Signs and symptoms may appear a few days after exposure. However, it may take years before you have any noticeable problems, depending on the organism causing the STI.

When to see a doctor

See a doctor immediately if:

You are sexually active and may have been exposed to an STI
You have signs and symptoms of an STI

Make an appointment with a doctor:

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

Causes

STDs or STIs can be caused by:

Bacteria. Gonorrhea, syphilis and chlamydia are examples of STIs that are caused by bacteria.
Parasites. Trichomoniasis is an STI caused by a parasite.
Viruses. STIs causes by viruses include HPV, genital herpes and HIV.

Other kinds of infections — hepatitis A, B and C viruses, shigella infection and giardia infection — can be spread through sexual activity, but it's possible to be infected without sexual contact.

Risk factors

Anyone who is sexually active risks some degree of exposure to an STD or STI. Factors that may increase that risk include:

Having unprotected sex. Vaginal or anal penetration by an infected partner who isn't wearing a latex condom significantly increases the risk of getting an STI. Improper or inconsistent use of condoms can also increase risk.

Oral sex may be less risky, but infections can still be transmitted without a latex condom or a dental dam — a thin, square piece of rubber made with latex or silicone.
Having sexual contact with multiple partners. The more people you have sexual contact with, the greater your risk.
Having a history of STIs. Having one STI makes it much easier for another STI to take hold.
Being forced to engage in sexual activity. Dealing with rape or assault is difficult, but it's important to see a doctor as soon as possible to receive screening, treatment and emotional support.
Misuse of alcohol or use of recreational drugs. Substance misuse 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.
Being young. Half the new STIs occur in people between the ages of 15 and 24.

Transmission from mothers to infants

Certain STIs — such as gonorrhea, chlamydia, HIV and syphilis — can be passed from mothers to their infants during pregnancy or delivery. STIs in infants can cause serious problems or even death. All pregnant women should be screened for these infections and treated.

Complications

Because many people in the early stages of an STD or STI experience no symptoms, screening for STIs is important to prevent complications.

Possible complications include:

Pelvic pain
Pregnancy complications
Eye inflammation
Arthritis
Pelvic inflammatory disease
Infertility
Heart disease
Certain cancers, such as HPV-associated cervical and rectal cancers

Prevention

There are several ways to avoid or reduce your risk of STDs or STIs.

Abstain. The most effective way to avoid STIs is to not have (abstain from) sex.
Stay with one uninfected partner. Another reliable way of avoiding STIs is to stay in a long-term relationship in which both people have sex only with each other and neither partner is infected.
Wait and test. 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 to prevent skin-to-skin contact between the oral and genital mucous membranes.
Get vaccinated. Getting vaccinated early, before sexual exposure, is also effective in preventing certain types of STIs. Vaccines are available to prevent 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, although it can be given as early as age 9. If not fully vaccinated at ages 11 and 12, the CDC recommends getting the vaccine through age 26.

The hepatitis B vaccine is usually given to newborns, and the hepatitis A vaccine is recommended for 1-year-olds. Both vaccines are recommended for people who aren't already immune to these diseases and for those who are at increased risk of infection, such as men who have sex with men and IV drug users.
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.

Condoms made from natural membranes are not recommended because they're not effective at preventing STIs. Also, keep in mind that while latex condoms reduce your risk of exposure to most STIs, they provide less protection for STIs involving exposed genital sores, such as HPV or herpes.

Also, nonbarrier forms of contraception, such as birth control pills or intrauterine devices (IUDs), 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.
Communicate. Before any serious sexual contact, communicate with your partner about practicing safer sex. Be sure you specifically agree on what activities will and won't be OK.
Consider male circumcision. For men, there's evidence that circumcision can help reduce the risk of acquiring HIV from a woman with HIV by as much as 60%. Male circumcision may also help prevent transmission of genital HPV and genital herpes.
Consider using preexposure prophylaxis (PrEP). The Food and Drug Administration (FDA) has approved the use of two combination drugs to reduce the risk of HIV infection in people who are at very high risk. They're emtricitabine plus tenofovir disoproxil fumarate (Truvada) and emtricitabine plus tenofovir alafenamide fumarate (Descovy).

Your doctor will prescribe these drugs for HIV prevention only if you don't already have HIV. You will need an HIV test before you start taking PrEP and then every three months as long as you're taking it.

Your doctor will also test your kidney function before prescribing Truvada and continue to test it every six months. If you have hepatitis B, you should be evaluated by an infectious disease or liver specialist before beginning therapy.

These drugs must be taken every day, exactly as prescribed. If you use Truvada daily, you can lower your risk of getting HIV from sex by about 99% and from injection drug use by more than 74% percent, according to the U.S. Centers for Disease Control and Prevention. Research suggests that Descovy is similarly effective in reducing the risk of getting HIV from sex. However, Descovy hasn't been studied in people who have receptive vaginal sex. Using additional prevention, such as condoms, can lower your risk even more and prevent other STIs.

Diagnosis

If your sexual history and current signs and symptoms suggest that you have a sexually transmitted disease (STD) or a sexually transmitted infection (STI), your doctor will do a physical or pelvic exam to look for signs of infection, such as a rash, warts or discharge.

Tests

Laboratory tests can identify the cause and detect coinfections you might also have.

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 open genital sores, your doctor may test fluid and samples from the sores to diagnose the type of infection.

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. Screening is recommended for:

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. Experts recommend that people at high risk have an HIV test every year.
Everyone born between 1945 and 1965. There's a high incidence of hepatitis C in people born between 1945 and 1965. Since the disease often causes no symptoms until it's advanced, experts recommend that everyone in that age group be screened for hepatitis C.
Pregnant women. All pregnant women will generally be screened for HIV, hepatitis B, chlamydia and syphilis at their first prenatal visit. 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 changes in the cells of the cervix, including inflammation, precancerous changes and cancer. Cervical cancer is often caused by certain strains of HPV.

Experts recommend that women have a Pap test every three years starting at age 21. After age 30, experts recommend women have an HPV test and a Pap test every five years. Or, women over 30 could have a Pap test alone every three years or an HPV test alone every three years.
Women under age 25 who are sexually active. Experts recommend that all sexually active women under age 25 be tested for chlamydia infection. The chlamydia test uses a sample of urine or vaginal fluid you can collect yourself.

Reinfection by an untreated or undertreated partner is common, so you need the second test to confirm that the infection is cured. You can catch chlamydia multiple times, so 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 hepatitis B also may be recommended.
People with HIV. If you have HIV, it dramatically raises your risk of catching other STIs. Experts recommend immediate testing for syphilis, gonorrhea, chlamydia and herpes after being diagnosed with HIV. They also recommend that people with HIV be screened for hepatitis C.

Women with HIV may develop aggressive cervical cancer, so experts recommend they have a Pap test at the time of the HIV diagnosis or within a year of becoming sexually active if they are under 21 and have HIV. Then, experts recommend repeating the Pap test every year for three years. After three negative tests, women with HIV can get a Pap test every three years.
People who have a new partner. Before having vaginal or anal intercourse with new partners, be sure you've both been tested for STIs. However, routine testing for genital herpes isn't recommended unless you have symptoms.

It's also possible to be infected with an STI yet still test negative, particularly if you've recently been infected.

Treatment

STDs or STIs caused by bacteria are generally easier to treat. Viral infections can be managed but not always cured.

If you are pregnant and have an STI, getting treatment right away can prevent or reduce the risk of your baby becoming infected.

Treatment for STIs 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 necessary to finish the prescription. If you don't think you'll be able to take medication as prescribed, tell your doctor. A shorter, simpler course of treatment may be available.

In addition, it's important to abstain from sex until seven days after you've completed antibiotic treatment and any sores have healed. Experts also suggest women be retested in about three months because there's a high chance of reinfection.
Antiviral drugs. If you have herpes or HIV, you'll be prescribed an antiviral drug. You'll have fewer herpes recurrences if you take daily suppressive therapy with a prescription antiviral drug. However, it's still possible to give your partner herpes.

Antiviral drugs can keep HIV infection in check for many years. But you will still carry the virus and can still transmit it, though the risk is lower.

The sooner you start HIV treatment, the more effective it is. If you take your medications exactly as directed, it's possible to reduce the viral load in the blood so that it can hardly be detected.

If you've had an STI, ask your doctor how long after treatment you need to be retested. Getting retested will ensure that the treatment worked and that you haven't been reinfected.

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. If they're infected, they can then be treated.

Each state has different requirements, but most states require that certain STIs be reported to the local or state health department. Public health departments often employ trained disease intervention specialists who can help notify partners and refer people for treatment.

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

Coping and support

It can be traumatic to find out you have an STD or STI. You might be angry if you feel you've been betrayed or ashamed if you might have infected others. At worst, an STI can cause chronic illness and death, even with the best care that's available.

These suggestions may help you cope:

Hold off placing blame. Don't assume that your partner has been unfaithful to you. One (or both) of you may have been infected by a past partner.
Be honest with health care workers. Their job is not to judge you, but to provide treatment and 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 every service, local health departments have STI programs that provide confidential testing, treatment and partner services.

Preparing for an appointment

Most people don't feel comfortable sharing the details of their sexual experiences, but the doctor's office is one place where you have to provide this information so that you can get the right 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, vitamins or supplements 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 is the infection 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 other health conditions. How can I best manage them together?
Should I avoid being sexually active while I'm 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 your doctor may ask:

What symptoms made you decide to come in? How long have you had these symptoms?
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? In the past two months?
When was your most recent sexual encounter?

What you can do in the meantime

If you think you might have an STI, it's best to abstain from sexual activity until you've talked with your doctor. If you do engage in sexual activity before seeing your doctor, be sure to follow safe sex practices, such as using a condom.