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Common Types of STIs

There are more than 20 types of sexually transmitted infections (STIs). Here’s what to know about several of the most common types.


Chlamydia is a common STI you can get by being infected with the bacteria Chlamydia trachomatis. It can cause permanent damage in women that can make it difficult or impossible to get pregnant.


You may not notice any symptoms if you’re infected. Women sometimes have vaginal discharge or feel burning when peeing. Men may have a discharge from their penis, feel burning when peeing or have pain and swelling in the testicles. An infection in the anus can cause rectal pain, discharge and bleeding. An infection in the mouth can cause pain in the mouth or the throat when swallowing or sores in the mouth.


Your doctor can test you for chlamydia with a urine test, a swab of your genital area, throat or rectum or nucleic acid amplification tests (NAATs). Women under age 25 and older women with risk factors for chlamydia (such as new or multiple sex partners or a sex partner with an STI) should be screened. All pregnant women under age 25, and those older than 25 with risk factors, should be screened at their first prenatal visit and again in the third trimester.


A one-day or seven-day course of antibiotics can cure chlamydia. You should wait an extra seven days after treatment before having sex again, so you don’t spread the infection to your partner(s). Your provider may prescribe antibiotics for your partner(s) as well.


Gonorrhea is an STI you get from infection with the bacteria Neisseria gonorrhoeae. It’s very common, especially in people ages 15 to 24, and it can infect your genitals, rectum and throat. Gonorrhea can cause infertility and joint infections and can increase your risk of catching HIV. Pregnant women can spread the infection to the baby, where it can cause serious complications.


Often, you won’t notice any symptoms. Sometimes, women have pain or burning when peeing, vaginal discharge and bleeding between periods. Men might have burning when peeing, a discharge from the penis that looks yellow, green or white or pain and swelling in the testicles. Symptoms in the rectum could be discharge, bleeding, itching and pain when pooping. You may have a sore throat, if you have a throat infection.


Your doctor can test you for gonorrhea with a urine test, a swab of your genital area, throat or rectum or nucleic acid amplification tests (NAATs). You should be tested every year if you’re a sexually active woman under age 25, a woman with new or multiple sex partners or a sex partner of someone with an STI. Pregnant women under age 25, and those over 25 with risk factors, should be tested.


Antibiotics can cure gonorrhea. Your doctor will probably give you a single injection of ceftriaxone. Gonorrhea is becoming more resistant to antibiotics, though, so your doctor may ask you to come in for another test a week after your injection to make sure the infection has gone away. For this reason, you should wait seven days after treatment before having sex again so you don’t spread the infection to your partner(s).


Syphilis is an STI you can get from the bacteria Treponema pallidum. You are at higher risk for syphilis if you are a gay or bisexual man, have HIV, take pre-exposure prophylaxis (PrEP) to help prevent HIV or have a partner who tested positive. Pregnant women can pass syphilis along to their baby, and it can cause serious complications, including stillbirth.


Syphilis progresses through four stages:

  • In the primary stage, you may notice firm, round, painless sores in the area where you’re infected.
  • In the secondary stage, you may have a rash or sores on your mouth, vagina or anus. You may also have fever, headaches, sore throat, hair loss, weight loss, muscle aches and fatigue.
  • In the latent stage, you still have syphilis in your body, but you don’t have symptoms.
  • In the tertiary stage, the infection spreads to your brain, nervous system, heart and blood vessels. Thanks to antibiotics, most people don’t have this stage anymore, but when it develops it’s very serious. If it occurs, it usually happens 10 to 30 years after the infection started.


The first test for syphilis is usually a blood test that shows whether you have antibodies to certain bacteria, including those that cause syphilis.

If that test is positive, you will likely have another blood test, which tests specifically for the bacteria that causes the infection. Providers usually use the first test to screen for syphilis and the second test to confirm the diagnosis. However, if you’ve been infected with syphilis in the past, your second test will probably be positive. That’s because your body will have the antibodies for a long time.

In the secondary stage, your provider can test fluid from a sore to check for syphilis. If necessary, your provider can also collect cerebrospinal fluid with a spinal tap to see if the infection is affecting your nervous system.

You should be tested regularly if you are a gay or bisexual man, have HIV, take PrEP or have a partner who has tested positive for syphilis. Pregnant women should be tested at least once during pregnancy.


Syphilis is easiest to cure in its early stages. It’s usually treated with a penicillin injection. If you are allergic to penicillin, there are alternative treatments. You should wait until your sores heal before having sex again, so you don’t spread the infection to your partner(s).

For late latent syphilis, you may need three injections. Late treatment will stop the infection, but it can’t reverse the damage that’s already done.


Herpes is an infection you get from the herpes simplex type 1 virus (HSV-1) or type 2 virus (HSV-2). HSV-1 (also known as oral herpes) often causes cold sores and fever blisters in the mouth. HSV-1 can also spread to the genitals during oral sex. HSV-2 spreads through sexual contact.

Both are common infections. In fact, it is estimated that 50% to 80% of American adults carry HSV-1. Genital herpes caused by HSV-1 or HSV-2 affects one in six people in the United States between the ages of 14 and 49.

You’re at higher risk for herpes if you have multiple sex partners, have another STI or a history of STIs or are female. A genital herpes infection can make you more likely to get HIV.


Usually, you’ll have no symptoms or very mild symptoms. It’s possible to have an outbreak with blisters or sores on your genitals, rectum or mouth. You may have flu-like symptoms during an outbreak.


Your doctor may be able to diagnose herpes by looking at the sores. They can also test a fluid sample from a sore. If you don’t have any sores, they can test your blood for antibodies or the virus’s DNA with a polymerase chain reaction (PCR) test. Testing for the herpes virus can be challenging, though, because it doesn’t always show up in routine testing.

Treatment: Herpes can’t be cured, but antiviral medication can prevent or shorten an outbreak. It can also make it less likely that you will spread herpes.

Human papillomavirus (HPV)

HPV infection is the most common STI. It can occur with skin-to-skin contact during vaginal, anal or oral sex. It’s often found in people in their late teens and early 20s. It usually goes away on its own, but if it doesn’t it can cause genital warts or cancers of the cervix, vulva, vagina, penis or anus. You’re at higher risk for HPV if you have a new sex partner.

The good news is there’s a vaccine that can help prevent HPV, as well as the types of cancer linked to HPV. Vaccinations are recommended for everyone at age 11 or 12 years and everyone under age 26 who hasn’t already been vaccinated. If you’re age 27 through 45, talk to your health care provider about vaccination. It’s not as effective in this age group, but it may be a good idea for some people.


Most people don’t have any signs or symptoms of HPV infection. You may notice genital warts, which look like small bumps in the genital area. Or you may develop warning signs of complications such as cervical cancer.


Women age 21 to 65 should have routine Pap tests. These tests check for abnormalities that could become cervical cancer (one of the complications of HPV). Depending on your age, you should have a Pap test every three to five years. Talk to your provider about the frequency and tests that are best for you.

There is no simple test to find HPV in men


There is no treatment for HPV. If you have genital warts, your doctor can treat them with in-office procedures or provide prescription medication. Precancerous changes in your cervix can also be treated. Treatment for other HPV-related cancers depends on the type of cancer. Treatment is more effective when cancers are spotted early.


HIV infection is caused by sexual contact, contact with infected blood or sharing needles. Babies can become infected by their mothers during pregnancy, childbirth or breastfeeding.

Over a long time, HIV can weaken your immune system and you can develop AIDS. You are at higher risk of contracting HIV if you have another STI (such as syphilis, gonorrhea or herpes). Pre-exposure prophylaxis (PrEP) medication can help prevent HIV infection.


Two to four weeks after you’re infected with HIV, you may have flu-like symptoms that last for a few weeks – but some people don’t feel any symptoms. After that, you still have HIV in your body, but you probably won’t have symptoms for a long time. This is why it’s important to test regularly for HIV if you are sexually active.

Untreated HIV will often become AIDS in eight to ten years. People with AIDS are more likely to get infections or cancers that they wouldn’t get with a healthy immune system.


You can have an HIV test of your blood or saliva. Self-tests look for antibodies in your saliva and can take three to 12 weeks after exposure before you test positive. Your provider, however, can test your blood, which will give you results more quickly.

Everyone ages 13 to 64 who are sexually active should be tested, including pregnant women. It’s a good idea to talk to your provider about testing schedules. You may need testing every year, or even every three to six months, depending on your risk.


There is no cure for HIV, but medications called antiretroviral therapy (ART) can keep it under control – even to the point of being undetectable – and help stop HIV from spreading to sex partners. Everyone with HIV should be on ART.


There are five different viruses that can cause hepatitis B infection. Most of the time, these infections go away quickly. But when they don’t, they can cause liver damage and liver failure.

People with HIV are more likely to have long-term hepatitis B. (Hepatitis A and C are not considered STIs, although they can be passed on to sexual partners.)

A vaccine helps prevent hepatitis B infection and is recommended for all babies as soon as possible after they are born.


You might not notice any signs of hepatitis infection, or you could experience fever, fatigue, joint pain, loss of appetite, nausea, vomiting and stomach pain. You could also have signs of liver disease such as jaundice, dark urine and fluid build-up in your abdomen, arms or legs. You could have liver disease without symptoms for many years.


Blood tests can detect hepatitis viral markers or antibodies. Everyone age 18 and older should be screened at least once. People at higher risk, such as those with multiple sex partners or who have used injected drugs, should talk to their doctors about the best testing schedule.


If you think you’ve been exposed to hepatitis B and you haven’t been vaccinated, a vaccination within 24 hours may help. You’ll need two more doses later to be fully vaccinated. You can also get an injection of hepatitis B immune globulin (HBIG). If you have chronic hepatitis B, medication can help keep your liver healthy for as long as possible.

Mycoplasma genitalium

Mycoplasma genitalium (MG) is a sexually transmitted bacteria that can cause cervix infections, pelvic inflammatory disease (PID), infertility, miscarriage and preterm delivery.


Women often don’t notice symptoms at first. They may have an unusual vaginal discharge with a foul odor. If you develop PID, you might have pelvic pain, pain during sex and abnormal vaginal bleeding.

Men might notice a thin, watery discharge from the penis or a burning feeling when urinating.


It’s possible to test for MG with a urine sample or cervical or vaginal swab. But if you have a cervical infection or PID, your provider might treat you for it without testing you. If you’re not responding to treatment, your provider might then test for MG.


MG is treated with two antibiotics. The first is doxycycline to treat PID. Your provider will then choose the second antibiotic carefully, since there’s a growing strain of MG that’s resistant to antibiotics. Your provider may also recommend testing your partner(s) or prescribing them the same antibiotic.

If you need STI testing, contact your health care provider, a Banner Urgent Care, your local department of health, mobile clinics or a local college or university. Many cities and counties provide low-cost, same day testing at walk-in clinics. You can search online for “STI clinic near me” to find the closest one to you.