Sexually transmitted infections (STIs)
Sexually transmitted infections (STIs) are passed from one person to another through unprotected sex or genital contact.
transmitted diseases, or STDs (sometimes called sexually transmitted
infections, or STIs) affect people of all ages, backgrounds, and from
all walks of life. In the U.S. alone there are approximately 20 million
new cases each year, about half of which occur among youth ages 15-24
Getting the facts about STDs/STIs and sexual health is increasingly
important. We invite you to explore our website and learn more about
specific STDs/STIs, tips for reducing risk, and ways to talk with health
care providers and partners.
STD or STI? What’s the difference?
Diseases that are spread through sexual contact are usually referred
to as sexually transmitted diseases or STDs for short. In recent years,
however, many experts in this area of public health have suggested
replacing STD with a new term—sexually transmitted infection, or STI.
Why the change? The concept of “disease,” as in STD, suggests a clear
medical problem, usually some obvious signs or symptoms. But several of
the most common STDs have no signs or symptoms in the majority of
persons infected. Or they have mild signs and symptoms that can be
easily overlooked. So the sexually transmitted virus or bacteria can be
described as creating “infection,” which may or may not result in
“disease.” This is true of chlamydia, gonorrhea, herpes, and human
papillomavirus (HPV), to name a few.
For this reason, for some professionals and organizations the term
“disease” is being replaced by “infection.” ASHA has used the term STD
since 1988 and it appears in hundreds of published ASHA documents,
including this site. Users of this site will continue to see it for some
time. But in moving forward, you will also begin to see increased use
of the term STI.
But there is not consensus in the medical and public health
community, as H. Hunter Handsfield, MD, Professor Emeritus at Washington
University Center for AIDS and STD notes in his essay for the journal Sexually Transmitted Diseases.
While making arguments for both terms, Handsfield suggests, “Those who
prefer either term should use it freely, with neither defensiveness nor
pride in either one.” Read his thoughts and share your comments on STD Prevention Online.
Or is it time for a new term? Medical linguist Janet Byron Anderson,
PhD, argues that we do and proposes “sexually transmissible infectious
disease (STID).” You can read her take here.
Chlamydia is the most common STI in the USA and is easily passed on
during sex. Most people don't experience any symptoms, so they are
unaware they're infected.
In women, chlamydia can cause pain or a burning sensation when
urinating, a vaginal discharge, pain in the lower abdomen during or
after sex, and bleeding during or after sex or between periods. It can also cause heavy periods.
In men, chlamydia can cause pain or a burning sensation when
urinating, a white, cloudy or watery discharge from the tip of the
penis, and pain or tenderness in the testicles.
It's also possible to have a chlamydia infection in your rectum (bottom), throat or eyes.
Diagnosing chlamydia is done with a urine test or by taking a swab of the affected area. The infection is easily treated with antibiotics, but can lead to serious long-term health problems if left untreated, including infertility.
Read more about chlamydia.
Genital warts are small fleshy growths, bumps or skin changes that
appear on or around your genital or anal area. They're caused by the human papilloma virus (HPV) and are the second most common STI in America after chlamydia.
The warts are usually painless, but you may notice some itching or redness. Occasionally, they can cause bleeding.
You don't need to have penetrative sex to pass the infection on because HPV is spread by skin-to-skin contact.
Several treatments are available for genital warts, including creams and freezing the warts (cryotherapy).
Read more about genital warts.
Genital herpes is a common infection caused by the herpes simplex virus (HSV), which is the same virus that causes cold sores.
Some people develop symptoms of HSV a few days after coming into
contact with the virus. Small, painful blisters or sores usually
develop, which may cause itching or tingling, or make it painful to
After you've been infected, the virus remains dormant (inactive) most
of the time. However, certain triggers can reactivate the virus,
causing the blisters to develop again, although they're usually smaller
and less painful.
It's easier to test for HSV if you have symptoms. Although there's no
cure for genital herpes, the symptoms can usually be controlled using
Read more about genital herpes.
Gonorrhoea is a bacterial STI easily passed on during sex. About 50%
of women and 10% of men don't experience any symptoms and are unaware
In women, gonorrhoea can cause pain or a burning sensation when
urinating, a vaginal discharge (often watery, yellow or green), pain in
the lower abdomen during or after sex, and bleeding during or after sex
or between periods, sometimes causing heavy periods.
In men, gonorrhoea can cause pain or a burning sensation when
urinating, a white, yellow or green discharge from the tip of the penis,
and pain or tenderness in the testicles.
It's also possible to have a gonorrhoea infection in your rectum, throat or eyes.
Gonorrhoea is diagnosed using a urine test or by taking a swab of the
affected area. The infection is easily treated with antibiotics, but
can lead to serious long-term health problems if left untreated,
Read more about gonorrhoea.
Syphilis is a bacterial infection that in the early stages causes a
painless, but highly infectious, sore on your genitals or around the
mouth. The sore can last up to six weeks before disappearing.
Secondary symptoms such as a rash, flu-like illness or patchy hair loss may then develop. These may disappear within a few weeks, after which you'll have a symptom-free phase.
The late or tertiary stage of syphilis usually occurs after many
years, and can cause serious conditions such as heart problems, paralysis and blindness.
The symptoms of syphilis can be difficult to recognise. A simple blood test
can usually be used to diagnose syphilis at any stage. The condition
can be treated with antibiotics, usually penicillin injections. When
syphilis is treated properly, the later stages can be prevented.
Read more about syphilis.
HIV is most commonly passed on through unprotected sex. It can also
be transmitted by coming into contact with infected blood – for example,
sharing needles to inject steroids or drugs.
The HIV virus attacks and weakens the immune system, making it less
able to fight infections and disease. There's no cure for HIV, but there
are treatments that allow most people to live a long and otherwise
AIDS is the final stage of an HIV infection, when your body can no longer fight life-threatening infections.
Most people with HIV look and feel healthy and have no symptoms. When
you first develop HIV, you may experience a flu-like illness with a
fever, sore throat or rash. This is called a seroconversion illness.
A simple blood test is usually used to test for an HIV infection.
Some clinics may also offer a rapid test using a finger-prick blood test
or saliva sample.
Read more about HIV and AIDS and coping with a positive HIV test.
Trichomoniasis is an STI caused by a tiny parasite called Trichomonas
vaginalis (TV). It can be easily passed on through sex and most
people don't know they're infected.
In women, trichomoniasis can cause a frothy yellow or watery vaginal
discharge that has an unpleasant smell, soreness or itching around the
vagina, and pain when passing urine.
In men, trichomoniasis rarely causes symptoms. You may experience
pain or burning after passing urine, a whitish discharge, or an inflamed
Trichomoniasis can sometimes be difficult to diagnose and your GP may
suggest you go to a specialist clinic for a urine or swab test. Once
diagnosed, it can usually be treated with antibiotics.
Read more about trichomoniasis.
Pubic lice ("crabs") are easily passed to others through close
genital contact. They're usually found in pubic hair, but can live in
underarm hair, body hair, beards and occasionally eyebrows or eyelashes.
The lice crawl from hair to hair but don't jump or fly from person to
person. It may take several weeks for you to notice any symptoms. Most
people experience itching, and you may notice the lice or eggs on the
Pubic lice can usually be successfully treated with special creams or
shampoos available over the counter in most pharmacies or from a GP or
GUM clinic. You don't need to shave off your pubic hair or body hair.
Read more about pubic lice.
Scabies is caused by tiny mites that burrow into the skin. It can be
passed on through close body or sexual contact, or from infected
clothing, bedding or towels.
If you develop scabies, you may have intense itching that's worse at
night. The itching can be in your genital area, but it also often occurs
between your fingers, on wrists and ankles, under your arms, or on your
body and breasts.
You may have a rash or tiny spots. In some people, scabies can be confused with eczema. It's usually very difficult to see the mites.
Scabies can usually be successfully treated using special creams or
shampoos available over the counter in most pharmacies, or from a GP or
GUM clinic. The itching can sometimes continue for a short period, even
after effective treatment.
Read more about scabies.
Page last reviewed: 27/04/2015
Next review due: 31/03/2018