Passed between individuals during vaginal, anal, or oral sex, sexually transmitted diseases (STDs) can have serious-and even fatal-consequences if left untreated. Anyone who is sexually active is at risk for contracting STDs, but fortunately, there are steps that you can take to minimize your chance of infection. Read on to get the facts on the most common five STDs-and the steps you can take to help prevent them.


Overview: Often called a silent disease because the majority of men and women don't realize they've been infected, chlamydia is the most frequently reported bacterial STD in the United States. In fact, more than a million cases were reported in 2006, according to the Centers for Disease Control and Prevention (CDC). The consequences of leaving chlamydia untreated can be devastating. Infections of the mucous membranes lining the genitals can lead to pelvic inflammatory disease (PID), an infection that damages the uterus and fallopian tubes, in women and infertility in both sexes. Women infected with chlamydia are also up to five times more likely to contract HIV, if they are exposed to it.

Symptoms: Symptoms often occur one to three weeks after exposure. Women might notice a burning sensation when urinating or abnormal vaginal discharge, fever, lower back pain, abdominal pain, nausea, or bleeding between periods. Men may experience discharge from the penis, a burning sensation when urinating, or burning and itching around the opening of the penis. Swollen and painful testicles are an uncommon, but possible, symptom.

Prevention: Abstinence is always the best protection against any venereal disease, but latex condoms can drastically reduce risk of transmission if used consistently and correctly. All pregnant women should be checked, and the CDC recommends that yearly testing be done on all sexually active women 25 or younger and older women who are at higher risk from having new or multiple partners.

Human Papillomavirus (HPV)
HPV is a group of viruses that includes more than 100 different strains, and it is the most common STD in the United States. More than 30 of these viruses are sexually transmitted and can infect the genital areas of men and women. According to the CDC, approximately 20 million Americans currently have HPV, and more than 6 million people becoming newly infected each year. At least half of all sexually active adults will acquire genital HPV infection at some point in their lives.

Symptoms: Although the majority of those infected with HPV will not show any symptoms and clear the infection on their own, certain strains of the virus can cause genital warts, while other strains can cause cancers of the penis, vulva, vagina, cervix, and anus. Many individuals infected with HPV may notice small clusters of warts on the vulva, in the vagina or anus, or on cervix, scrotum, penis, groin, or thigh within a few weeks or months after initial exposure. Abnormal cells in the cervix can be detected by a Pap test. In addition, HPV tests are available, and the American Cancer Society recommends that women over the age of 30 get one.

Prevention: As with most STDs, abstinence and condoms provide the greatest degree of protection. The U.S. FDA has also recently approved an HPV vaccine, Gardasil, for females ages 9 to 26 who had not been previously infected with any of the strains covered by the vaccine. The vaccine prevents four common strains that cause 70 percent of all cervical cancer and 90 percent of all genital warts.

Genital Herpes
Overview: Most frequently caused by the type 2 herpes simplex virus (HSV), genital herpes is another extremely common STD. Up to 45 million people in the United States, ages 12 and older, are infected, according to the CDC. Many of those carrying this virus are unaware that they're infected and that they may be transmitting it to others. Genital HSV 2 infection is more common in women than in men, largely due to male-to-female transmission being more likely than female-to-male transmission. Those infected are at a higher risk of contracting HIV, if exposed, and infected mothers may transmit potentially fatal infections to their babies.


After initial exposure, symptoms can range from very mild to severe. One or several sores around the genitals or rectum is the most common sign, while flu-like symptoms such as swollen glands and fever may also be present. Those diagnosed with the first episode of genital herpes can expect to have several outbreaks within a year. These outbreaks will typically decrease in frequency over time. Additionally, although a positive HSV-2 blood test can indicate a genital herpes infection, a negative result doesn't necessarily mean a person isn't infected.


Again, abstinence and condoms are the best methods of prevention. In particular, those infected with herpes should abstain from sexual activity with uninfected partners during an outbreak.


Caused by the bacterium Neisseria gonorrhoeae, gonorrhea is transmitted through vaginal, anal, or oral sex, and may also be spread from an infected mother to her baby during delivery. According to the CDC, more than 700,000 people in the United States are infected with gonorrhea each year, and the highest reported rates are among young adults and sexually active teenagers. Left untreated, gonorrhea can cause serious and permanent health problems, such as PID and epididymitis (an inflammation of the tube at the back of the testicle that stores and carries sperm), both of which can lead to infertility.


Symptoms are often not present at all and can take as long as 30 days to appear. Men may notice white, green, or yellow discharge from the penis and swollen, painful testicles, while women might experience increased vaginal discharge or bleeding in between periods. Painful, burning sensations while urinating are also common symptoms in both sexes.


Abstaining from sex completely or using condoms consistently during sexual activity can drastically reduce the risk of transmission of gonorrhea. Several laboratory tests are available to diagnose gonorrhea, and the CDC says a high percentage of people who have gonorrhea also have chlamydia, so it's wise to be tested for other STDs, too. Gonorrhea can usually be cleared up with antibiotic treatment. Those infected should notify all recent sex partners and avoid sex until they have completed their treatment.

First identified in the U.S. in 1981, human immunodeficiency virus (HIV) is the most serious of all STDs. It differentiates itself from most other viruses by attacking the immune system, ultimately resulting in acquired immunodeficiency syndrome (AIDS), its final stage of infection. The CDC estimates that approximately 1 million people in the U.S. are currently living with HIV or AIDS, and about a quarter of them don't even know they're infected. HIV is most commonly transmitted through oral, vaginal, or anal sex, or sharing needles or syringes with an infected person. In some cases, a fetus or infant may be exposed to an infected mother while in utero or during birth. Though the occurrence is extremely low because of stringent donated blood testing, HIV can also be transmitted through blood transfusions.


Although some people may experience flu-like symptoms such as nausea, fatigue, fever, and headaches within three to six weeks after exposure, other signs of HIV can range widely and may not be present for several years. The only way to know for sure whether you are infected with HIV is to be tested.

Prevention: Practicing abstinence, using latex condoms when engaging in sexual activity, and avoiding intravenous drug use and not sharing needles/syringes with others are the best methods of protection against HIV. Even those who are at low risk should be tested for HIV at least once a year, the CDC says. Testing is also recommended after engaging in high-risk sexual contact with new partners or sharing needles for IV drug use.