Sexually Transmitted Infections (STIs)

What are sexually transmitted infections (STIs)?

Sexually transmitted infections (STIs) are infectious diseases passed from one person to another through unprotected sex or genital contact. STIs can cause severe damage to the body, even death. Except for colds and flu, STIs are the most common contagious (easily spread) infections in the United States, with millions of new cases each year. Although some STIs can be treated and cured, others cannot.

How are STIs transmitted?

A person with an STI can pass it to others by contact with skin, genitals, mouth, rectum, or body fluids. Anyone who has sexual contact vaginal, anal, or oral sex with another person may get an STI. STIs may not cause symptoms. Even if there are no symptoms, your health can be affected.

What causes STIs?

STIs are caused by bacterial or viral infections. STIs caused by bacteria are treated with antibiotics. Those caused by viruses cannot be cured, but symptoms can be treated.

How can you protect yourself from STIs?

The best way to prevent getting an STI is to not have any type of sexual activity, including oral, vaginal, and anal sex. But you can take several steps to lower your risk for an STI if you decide to become sexually active, or are currently sexually active. These include:

  • Any sexual relationship should be with only one uninfected partner. That partner should also not have any other partners.
  • Use a latex condom the correct way every time you have sex. Or use a female polyurethane condom plus medicine that kills sperm (topical microbicide).
  • Use sterile needles if you inject IV medicines.
  • Prevent and control other STIs. This will lower your risk for human papillomavirus (HPV).
  • Delay having sexual relationships as long as you can. The younger you are when you start having sex, the more likely you are to get an STI.
  • Have regular checkups for HIV and STIs.
  • Learn the symptoms of STIs and seek medical help as soon as possible if any symptoms develop.
  • Don’t have sexual intercourse during your monthly period.
  • Don’t have anal intercourse.
  • Don’t douche.

The Limits of Condoms

While condoms are effective in preventing the spread of some STIs, they are not perfect. Condoms are better at protecting against gonorrhea, chlamydia, HIV, and trichomoniasis. But they offer less protection against herpes, syphilis, and genital warts. These infections can spread through contact with skin lesions that are not covered by a condom. Finally, condoms offer virtually no protection against crabs and scabies.

What to do when diagnosed with an STI?

  • Begin treatment right away. Take the full course of medicines, and follow your doctor’s advice.
  • Don’t breastfeed a baby or use breastmilk to feed a baby if you are HIV positive.
  • Tell your local health department or all recent sexual partners and urge them to get medical checkups.
  • Don’t have sexual activity while getting treatment for an STI.
  • Have a follow-up test to be sure the STI has been successfully treated.

How can STIs affect pregnancy?

Having an STI during pregnancy can harm the baby. Gonorrhea and chlamydia both can cause health problems in the infant ranging from eye infections to pneumonia. Syphilis may cause miscarriage or stillbirth. HIV infection can pass to a baby during a vaginal birth.

If you are pregnant and you or your partner have had or may have an STI, inform your gynecologist. Your baby may be at risk. Tests for some STIs are offered routinely during prenatal care. It is best to treat the STI early to decrease the chances that your baby will get the infection. You and your partner both may have to be treated.

What are some common types of STIs?

Common STIs are listed below:-

Human immunodeficiency virus (HIV)

HIV is a virus that destroys the body’s ability to fight off infection. People who have HIV may not look or feel sick for a long time after infection. But if you are not diagnosed early and treated, you will eventually become very likely to get many life-threatening diseases and certain forms of cancer. The virus is passed on most often during sexual activity. It can also be passed on by sharing needles used to inject IV drugs. HIV can be passed to your baby during pregnancy, labor, delivery, and through breastfeeding. If you know early in your pregnancy that you are HIV positive, you can get treatment that greatly lowers your chance of passing on the virus to your child, the CDC says.

Human papillomavirus (HPV)

Genital Warts STD HPVHPV is a common sexually transmitted disease. Some types of HPV can cause genital warts (condylomas). These can happen on the inside or outside areas of the genitals. They may spread to the surrounding skin or to a sexual partner. Many other types of HPV cause no symptoms, so you may not know that you are infected. In most cases, the virus goes away and does not cause further health problems. But if the virus lasts, normal cells can change and become abnormal. Women with an HPV infection with high-risk types like HPV 16 and 18 have an increased risk of getting cervical cancer. Pap tests can detect HPV infection, as well as abnormal cervical cells.

An HPV vaccine protects against the types of HPV that cause most cervical cancers. It also protects against most genital warts in both men and women, and against anal cancer in men. Even with treatment for genital warts, the virus remains in the body and warts can reappear. Certain types of HPV can also cause warts on other body parts such as the hands. These are called common warts. These don’t generally cause health problems. If a pregnant woman has a large number of genital warts, the growths can complicate a vaginal delivery. If the warts block the birth canal, the woman may need a cesarean section.


Chlamydia is the most commonly reported STI in the U.S. It can affect both men and women. This infection may cause an abnormal genital discharge and burning with urination. In women, untreated chlamydia may lead to pelvic inflammatory disease (PID). Chlamydia can be treated with antibiotics. Unfortunately, many people with chlamydia have few or no symptoms of infection. The most common and serious complications occur in women. In addition to PID, these include tubal (ectopic) pregnancy and infertility. Chlamydia can also be carried in and affect the rectum. If you are pregnant and have chlamydia, the infection can be passed to your baby at birth. This can cause eye infections or pneumonia in your baby. With chlamydia, you are also more likely to have your baby too early.

Genital herpes

Genital herpes infections are caused by the herpes simplex virus (HSV). Symptoms may include painful blisters or open sores in the genital area. Tingling or burning sensation in the legs, buttocks, or genital area may happen just before the blisters show up. The herpes sores usually disappear within a few weeks. The virus stays in the body, and the sores may return from time to time. There is no cure for HSV, but medicine can shorten an outbreak and reduce symptoms. HSV can be passed on from the mouth to the genitals during oral sex. The virus can be passed on to sexual partners even if the person has no visible blisters. This is called asymptomatic shedding. HSV can also be spread to a baby at the time of childbirth. This causes a very severe infection in the infant.


Gonorrhea causes a discharge from the vagina or penis and painful or difficult urination. The most common and serious complications happen in women. They include pelvic inflammatory disease (PID), ectopic pregnancy, and infertility. Gonorrhea can be treated with antibiotics. Gonorrhea can also be carried in and affect the rectum. Gonorrhea at the time of childbirth can spread to the baby and cause severe eye infection.

Syphilisstd syphilis

The first symptom of syphilis is a painless open sore that usually shows up on the penis, in the vagina, or on the skin around either sexual organ. Untreated syphilis may go on to more advanced stages. These include a rash and over time problems with the heart and central nervous system. Syphilis can be treated with antibiotics. If a pregnant woman has untreated syphilis, the disease can cause dangerous, even fatal, problems for the baby. The way congenital syphilis affects the infant depends on how long the woman has had the disease and if or when she was treated for the infection. This form of syphilis can cause miscarriage, stillbirth, or death of the baby shortly after birth. According to the CDC, about 2 in 5 babies born to women with untreated syphilis may be stillborn or die from the infection in infancy.

Other diseases

Other diseases that may be sexually transmitted include:

  • Bacterial vaginosis
  • Chancroid
  • Cytomegalovirus infections
  • Lymphogranuloma venereum
  • Granuloma inguinale (donovanosis)
  • Molluscum contagiosum
  • Pubic lice
  • Scabies
  • Trichomoniasis
  • Vaginal yeast infections

What are the facts about STIs and teens?

STIs affect men and women of all backgrounds and economic levels. But nearly half of all STI cases in the U.S. happen in people younger than age 25.

STIs are on the rise. This may be because more sexually active people have multiple sex partners during their life.

Many STIs cause no symptoms at first. Also, many STI symptoms may look like those of other diseases not transmitted through sexual contact. This is especially true in women. Even STIs without symptoms can be spread to other people.

Women suffer more severe symptoms from STIs because:-

  • Some STIs can spread into the womb (uterus) and fallopian tubes and cause PID. This can lead to both infertility and tubal pregnancy.
  • STIs in women also may lead to cervical cancer.
  • STIs can be passed from a mother to her baby before or during birth.
  • Some infections of the newborn may be successfully treated. Others may cause a baby to be permanently disabled or even die.

Many STIs can be successfully treated when diagnosed early.