Sexually Transmitted Infections (STIs)

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What are Sexually Transmitted Infections (STIs)?

These infections are passed to the genitals - and the area around the genitals - by unprotected sexual activity with a person who is infected. There are also some STIs that can infect the mouth.

There are two main types: STIs that are caused by viruses and those caused by bacteria. The two most common STIs are caused by viruses: Human Papillomavirus (HPV) and herpes (HSV).

Why does it matter if they are caused by bacteria or viruses?

All STIs can be treated; but STIs caused by bacteria can be cured.

How do you get an STI?

If you have unprotected sexual activity with an infected partner, you can get an STI. This means oral sex, vaginal sex, anal sex or skin-to-skin contact in the genital area. You can also get STIs that are in the blood (Hepatitis B, C, syphilis and HIV (Human Immunodeficiency Virus, the virus that causes AIDS)) by sharing needles or “works” (paraphernalia associated with substance use). People who share straws or bills for cocaine or share crack pipes are at risk for Hepatitis C. You can get Hepatitis B from sharing razors, nail clippers or even toothbrushes used by a person who is infected.

How can you protect yourself?

There are three ways you can protect yourself: using condoms, getting tested and getting treated when necessary. Some people use a latex barrier for oral sex on the vulva or anus, but this is not very common.

What about vaccines?

There is a vaccine against Hepatitis B and two vaccines against several strains of HPV.

How do you know if you have an STI?

Sometimes there are signs or symptoms; sometimes there are not. See your health care provider if you notice:

  • something unusual in the vagina, around the anus, or on the vulva like a bump or sore
  • something unusual in the area around your genitals – thighs, buttocks or anywhere in the “shorts” area
  • unusual discharge
  • unusual smell
  • itching or irritation in these areas
  • inflammation in these areas

 How do you know you have an STI if there are no signs of infection?

  • Most people with HPV and HSV are unaware that they have it.
  • Most women with chlamydia are not aware they are infected. This is also true for about half of the men infected with chlamydia.

If you have had unprotected sexual activity (oral sex, vaginal or anal sex or skin-to-skin contact in the genital area) you may want to get tested even if you have not noticed anything unusual.

  • For women, the test for chlamydia and gonorrhea is usually a swab.
    • In some cases, a health care provider does a urine test on women for chlamydia and gonorrhea. (Urine tests are commonly used to diagnose chlamydia and gonorrhea in men.)
  • For HIV, Hepatitis B and C and syphilis the test is a blood test.
    • Many clinics and some health care providers offer a finger prick test for HIV - the rapid test - with almost immediate results.
  • When there is a sore and the health care provider suspects herpes, they can take a swab and send it to the lab for testing.
  • They can usually diagnose an HPV wart, or molluscum contagiosum (a skin infection) just by examining it.

What’s the difference between a Pap test and tests for STIs?

Health care providers do not routinely test for STIs when you have an internal exam or Pap test, unless you report something unusual. They may test if they see something unusual during the examination. Ask to be tested for STIs. Now that the new guidelines recommend starting Pap testing at 25, it is very important to check for STIs if you have had unprotected sexual activity before your first Pap test. Sometimes, a Pap test will show that a woman has HPV or herpes on the cervix. (See FAQ: HPV and cervical cancer)

What kinds of treatments are there?

The treatment (and cure) for chlamydia and gonorrhea is an oral antibiotic. There are some resistant strains, but this is not common yet.

A syphilis infection requires antibiotic injections to cure it.

People with HIV can take daily medication to keep it under control.

People with herpes can take medication during an outbreak to promote healing. Some people who get frequent herpes outbreaks take daily medication.

HPV warts and molluscum contagiosum are usually treated with liquid nitrogen although there are other treatments. It may take several treatments before the infections are gone.

What happens if you don’t get treated?

Chlamydia and gonorrhea can spread into the reproductive system if they are not treated. This can result in scarring of the fallopian tubes and possible infertility.

Syphilis can stay in the body if not treated and eventually cause organ damage and death.

It is easier to get HIV from unprotected sexual activity, including oral sex, if there is an existing untreated infection. People who do not take medication for HIV to maintain their immune system are more likely to get other infections and die of AIDS. Although complementary treatments may also boost the immune system, it is not recommended to use these therapies alone. Treating HIV also reduces the risk of transmission to others.

Do these infections go away for good?

When a person has taken their medication for a bacterial infection, it should be cured. It is, of course possible to get a new infection if you have unprotected sexual activity with an infected partner. That is why it is important for all your partners to be treated as well.


HIV can be managed with treatment. Currently, many people with HIV take one pill a day. There are side effects, but medication can help a person lead a normal life. Treatment can also reduce their ability to transmit the infection to others.


Some people with herpes have frequent outbreaks; others have occasional outbreaks. A person can get herpes on their genitals caused by the cold sore virus (HSV-1) from unprotected oral sex. These outbreaks may be less frequent than for people with HSV-2 . After an outbreak, HSV-2 (genital herpes) rests in the ganglia at the base of the spine until the next outbreak.

Most people are unaware that they have – or have had – herpes. It is common to get the infection when their partner has no visible sore.


A person’s immune system usually gets rid of HPV infections. Persistent HPV infections with cancer- causing types may cause changes to the cervix (See FAQ: HPV and cervical cancer).

What about vaginal infections?

Yeast, bacterial vaginosis (BV) and trichomoniasis can infect the vagina and vulva. It is possible, but not common, to infect a partner with yeast, which is caused by a fungus. Partners of women with BV do not need to be treated. However, trichomoniasis requires treatment for both partners because of the possibility of reinfection.

Unless you have had several yeast infections and are familiar with your symptoms, it is best to see a health care provider for correct diagnosis and treatment before buying over the counter medication. Your health care provider will take a vaginal smear to test for these infections.

(See FAQ: Keeping Your Vagina Healthy)

This FAQ may provide medical information, but is not meant to be a substitute for medical advice. When you have questions about your health, it is always advisable to ask a health care practitioner.

Created December 2013.