STIs are caused by bacteria, viruses, or other organisms. Treatments depend on the cause of the infection. Bacterial infections can be treated and cured with antibiotics. However, some bacteria are becoming resistant to antibiotics making treatment lengthier or more difficult. Viral infections are generally not curable, but medications can be used to ease symptoms and increase the time between symptoms flare-ups. Drug resistance can also be seen with some viruses. Other organisms include parasites, fungi, or protozoa. These are treated with antibiotics or other types of medications (depending on the organism).
STIs are usually spread through sexual contact, including vaginal, oral, and anal sex. The viruses and bacteria that cause STIs are normally carried in the semen, vaginal fluids, or blood. They enter the body through tiny tears or cuts in the mouth, anus, or genitals. STIs can be passed from person-to-person even without having sexual intercourse. For instance, someone can contract herpes or genital warts through skin-to-skin contact with an infected sore or area.
With most STIs, symptoms do not appear right away. Latency periods vary among specific infections. This makes it easier to transmit an infection to others.
Abstaining from sex or intimate contact is the most effective way to prevent an STI. If you are sexually active, you can reduce your chances of an STI by avoiding high-risk behaviors like unprotected sex and sex with multiple partners.
A latex condom should always be used when having sex. It's important to use a condom consistently and correctly. Vaccines are available for some infections. If you have questions about condom use or vaccination schedules, talk to your doctor.
You should see a doctor right away if you have:
Other symptoms of a STI may include:
Bacterial vaginosis (BV) is caused by a change in the balance of different kinds of bacteria in the vagina. When there are symptoms, they often appear as a form of vaginitis—an irritation of the vagina often associated with a vaginal discharge. BV is not sexually transmitted, though sexual activity increases the risk because it can change the balance of bacteria.
When diagnosed, chlamydia can be easily treated and cured. Untreated, chlamydia can cause reproductive and other health problems. It can cause bladder infections and pelvic inflammatory disease (PID), ectopic pregnancy, and sterility in both men and women. It can also cause eye infections in newborns. It is the most frequently reported infectious disease in the US.
Cytomegalovirus (CMV) is a member of the herpes virus group. Once infected, a person can carry the virus for life, even though they may never have active symptoms. In babies, transmission of CMV during pregnancy can cause permanent disability, including hearing loss and intellectual disability. This virus is also dangerous for people with weakened immune systems. In healthy adults who are infected with CMV, the symptoms may include swollen glands, sore throat, fever, and fatigue.
Gonorrhea is caused by specific bacteria, which is transmitted during vaginal, oral, or anal sexual intercourse. It can cause sterility, arthritis, and rarely, heart problems in both men and women. It can also cause eye infections in newborns.
Both herpes simplex virus-1 (HSV-1) and herpes simplex virus-2 (HSV-2, most common) can be sexually transmitted. HSV-1 is most often associated with cold sores and fever blisters. Like many other viruses, the HSV remains in the body for life. HSV can cause miscarriage or preterm delivery. If active herpes infections are present during childbirth, newborn infants may suffer health problems.
HIV is an infection that weakens the body’s ability to fight off infections. It can eventually lead to AIDS. This compromised immune system can make a carrier more susceptible to pneumonia, cancer, and a variety of opportunistic infections. Like many other viruses, HIV remains in the body for life.
Human papillomavirus (HPV) is a family of more than 100 common viruses. HPV can cause genital warts. The virus is easily spread during oral, genital, or anal sex with an infected partner. Some of these viruses are associated with cervical cancer.
Molluscum contagiosum can be transmitted by nonsexual, intimate contact. Small, pinkish-white, waxy, round polyps grow in the genital area or on the thighs, and there is often a tiny depression in the middle of the growth. Molluscum contagiosum belongs to a family of viruses called poxviruses, and it is generally spread by skin-to-skin contact. It can be spread sexually if growths are present in the genital area.
Pelvic inflammatory disease (PID) is a progressive infection that harms a woman's reproductive system. It is usually caused by a chlamydial or gonorrheal infection. It can lead to sterility, ectopic pregnancy, and chronic pain. PID is often caused by STIs, like gonorrhea and chlamydia.
Pubic lice are tiny parasitic insects that are generally found in the genital area of humans. Pubic lice are usually spread through intimate or sexual contact. Rarely, infestation can be spread through contact with an infested person's bed linens, towels, or clothes.
Scabies is an infestation of the skin with a microscopic mite. It is often sexually transmitted. However, school children often pass it to one another through casual contact.
Syphilis is caused by a specific bacteria. It is passed from person-to- person through direct contact with syphilis sores, which occur mainly on the external genitals, vagina, anus, or in the rectum. Sores also can occur on the lips and in the mouth. Though sores disappear without treatment, the bacteria is still in the body causing damage. If left untreated, the syphilis can remain in the body for life and lead to disfigurement, neurologic disorder, and death.
Trichomoniasis is a condition caused by a protozoan—a microscopic, one-cell organism. It is a common cause of vaginal infections. It is spread through vaginal intercourse.
American Sexual Health Association
Centers for Disease Control and Prevention
SEICCAN—Sex Information & Education Council of Canada
Sex & U—The Society of Obstetricians and Gynaecologists of Canada
2015 Sexually transmitted diseases treatment guidelines. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/std/tg2015/default.htm. Updated January 25, 2017. Accessed October 10, 2017.
Acute HIV infection. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T902526/Acute-HIV-infection. Updated November 4, 2015. Accessed October 10, 2017.
Bacterial vaginosis (BV). EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115494/Bacterial-vaginosis-BV. Updated September 26, 2017. Accessed October 10, 2017.
Congenital cytomegalovirus (CMV) infection and CMV in pregnancy. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116860/Congenital-cytomegalovirus-CMV-infection-and-CMV-in-pregnancy. Updated November 6, 2016. Accessed October 10, 2017.
Cytomegalovirus (CMV) infection in immunocompetent patients. EBSCO DynaMed Plus website. Available at:http://www.dynamed.com/topics/dmp~AN~T906245/Cytomegalovirus-CMV-infection-in-immunocompetent-patients. Updated November 1, 2016. Accessed October 10, 2017.
Genital herpes. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T114875/Genital-herpes. Updated April 27, 2017. Accessed October 10, 2017.
Genital herpes and your baby. Pregnancy Info.net website. Available at: https://www.pregnancy-info.net/stds_herpes_pregnancy.html. Accessed October 10, 2017.
Having sex during your period: Q&A. Epigee website. Available at: https://www.epigee.org/menstruation/sex.html. Accessed October 10, 2017.
Molluscum contagiosum. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116448/Molluscum-contagiosum. Updated August 20, 2015. Accessed October 10, 2017.
Other STDs. Centers for Disease Control and Prevention website. Available at: https://www.cdc.gov/std/general/other.htm. Updated September 27, 2017. Accessed October 10, 2017.
Last reviewed October 2017 by EBSCO Medical Review Board Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.