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STIs and STDs

Overview of STIs and STDs

Sexually transmitted infections (STIs), also called sexually transmitted diseases (STDs), are conditions that occur from the spread of certain bacteria, viruses, or parasites during sexual activity.


STD symptoms vary according to the type of infection. In some cases, there are no signs or symptoms at all. Common symptoms include:

  • Sores, blisters, or unusual lumps in the genital area
  • Unusual vaginal discharge, including green, gray, white, yellow, or foul-smelling discharge
  • Abnormal vaginal bleeding
  • Pain, itching, or burning in the genital region
  • Painful or unusually frequent urination
  • Pain during intercourse
  • Pain around the pelvic area
  • Fever
  • Fatigue
  • Enlarged lymph nodes
  • Rash


Parasites, bacteria, and viruses can cause STIs and STDs:

  • Parasitic STDs include trichomonas vaginalis and some insects such as pubic lice (“crabs”)
  • Bacterial STDs include syphilis, gonorrhea, and chlamydia
  • Viral STDs include HIV, herpes, HPV, and hepatitis

All types of infection can be spread through oral sex, vaginal sex, anal sex, and sexual touching. STIs/STDs can be spread from person to person through sexual contact, even if the infected person has no apparent symptoms.

In addition to sexual transmission, some infections can be passed from a woman to her child during pregnancy or at birth. Shared needles such as those used in tattooing or to inject drugs can also transmit blood-borne infections such as HIV and hepatitis.

A few STIs/STDs, such as pubic lice, can also be spread by close physical contact, even if that contact is non-sexual. STIs cannot, however, be spread by casual contact such as sharing a toilet or shaking hands.

Regardless of the source of the first STD/STI exposure, STIs/STDs can be spread by an infected person through sexual contact.


Common STIs/STDs include:

  • Gonorrhea
  • Chlamydia
  • Syphilis
  • Pelvic inflammatory disease (PID)
  • Herpes
  • Hepatitis B and Hepatitis C
  • HIV/AIDs
  • Genital warts (from human papillomavirus, or HPV)
  • Trichomoniasis
  • Chancroid
  • Scabies

Some STIs/STDs lead to serious health problems, including infertility, ectopic pregnancy, and cancer. If left untreated, some may be fatal. Women are more likely than men to develop severe complications from sexually transmitted infections.

Risk factors

All sexual activity, including oral, vaginal, and anal sex, carries some risk of exposure to STIs/and STDs. Also, the following factors can increase your risk of contracting STIs/STDs:

  • Having unprotected sex: While anal and vaginal penetrative sex carry the highest risk of transmission, unprotected oral sex without the use of a dental dam or latex condom still increases the likelihood of infection.
  • Having multiple partners: More partners increases the chances of exposure to one or more STIs.
  • Being immunocompromised: Having a weak immune system can increase the likelihood that exposure to a sexually transmitted disease will lead to infection.
  • Having a previous STI diagnosis: Prior history of STI/STD infection increases the chances that you will be infected with another in the future.
  • Having a history of sexual assault: Though it is often challenging to seek care following sexual assault or rape, seeing a doctor as quickly as you can is vital. It ensures you have access to adequate screening, treatment, and support.
  • Use of recreational substances: Drug and alcohol use can impair judgment and lead to riskier sexual activities.
  • Being sexually active while young: The majority of STIs occur among sexually active people under the age of 24.


Sexually transmitted infections are prevalent. Every year, the Centers for Disease Control and Prevention (CDC) estimate that 20 million more people are infected. Since many people never show symptoms, they are never diagnosed, but can still spread infections to others.

Any sexual activity or contact with the bodily fluids of others carries some risk of exposure to STIs/STDs. Some methods to reduce this risk include:

  • Abstinence, or not engaging in any sexual activity with another person.
  • Monogamy, being in an exclusive sexual relationship with someone who does not have any STIs/STDs.
  • Safer sex practices, including using barrier protection such as latex condoms or dental dams every time you have sex and limiting the number of your sexual partners.
  • Vaccination. Some STIs/STDs can be prevented with a vaccination. For example, healthcare providers can give you vaccinations for hepatitis and HPV, which can cause genital warts, cervical dysplasia, and cervical cancer.
  • Avoiding sharing needles because injecting drugs with shared needles or using unsanitary piercing or tattoo needles dramatically increases your risk of contracting an STI.

To reduce the severity of your symptoms and the potential that you will develop serious complications such as infertility or cancer, it is also essential to get tested regularly and undergo screenings for STDs/STIs, as recommended by your doctor.

Annual exams and STI/STD screenings are an essential part of your health care plan. If you experience symptoms of a sexually transmitted disease, visit Dignity Health as soon as possible.

The information contained in this article is meant for educational purposes only and should not replace advice from your healthcare provider.