Sexually transmitted diseases (STDs) — or sexually transmitted infections (STIs) — are generally acquired by sexual contact. The organisms (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 nonsexual, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.
STDs don’t always cause symptoms. It’s possible to contract sexually transmitted diseases from people who seem perfectly healthy and may not even know they have an infection.
Sexually transmitted diseases (STDs) or sexually transmitted infections (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 odd-smelling vaginal discharge
- Unusual vaginal bleeding
- Pain during sex
- 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 after exposure, or it may take years before you have any noticeable problems, depending on the organism.
Sexually transmitted diseases (STDs) or sexually transmitted infections (STIs) 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 kinds of infections, although it’s possible to be infected without sexual contact. Examples include the hepatitis A, B, and C viruses, shigella, and Giardia intestinalis.
Anyone who is sexually active risks some degree of exposure to a sexually transmitted disease (STD) or a sexually transmitted infection (STI). Factors that may increase that risk includes:
- 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 your 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. This is true for concurrent partners as well as monogamous consecutive relationships.
- Having a history of STIs. Having one STI makes it much easier for another STI to take hold.
- Anyone forced to have sexual intercourse or sexual activity. Dealing with rape or assault can be difficult, but it’s important to see a doctor as soon as possible so that you can 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 STIs occur in people between the ages of 15 and 24.
- Men who request prescriptions for drugs to treat erectile dysfunction. Men who ask their doctors for prescriptions for drugs have higher rates of STIs. Be sure you are up to date on safe sex practices if you ask your doctor for one of these medications.
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 or even death. All pregnant women should be screened for these infections and treated.
Because many people in the early stages of a sexually transmitted disease (STD) or sexually transmitted infection (STI) experience no symptoms, screening for STIs is important in preventing complications.
- Pelvic pain
- Pregnancy complications
- Eye inflammation
- Pelvic inflammatory disease
- Heart disease
- Certain cancers, such as HPV-associated cervical and rectal cancers
There are several ways to avoid or reduce your risk of sexually transmitted diseases (STDs) or sexually transmitted infections (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 mutually monogamous 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 direct (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.
- 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.
- 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. There’s evidence that male circumcision can help reduce a man’s risk of acquiring HIV from a woman who is infected (heterosexual transmission) by as much as 60%. Male circumcision may also help prevent transmission of genital HPV and genital herpes.
If your sexual history and current signs and symptoms suggest that you have a sexually transmitted disease (STD) or a sexually transmitted infection (STI), 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.
Some experts recommend repeating the chlamydia test three months after you’ve had a positive test and been treated. 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 within a year of being diagnosed with HIV, and then again six months later.
- 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.
Sexually transmitted diseases (STDs) or sexually transmitted infections (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 follow through. 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 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 treatment, the more effective it is. If you take your medications exactly as directed, it’s possible to reduce your virus count so low 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.