What Do Sexually Transmitted Infections (STIs) Look Like on Skin?

Most sexually transmitted infections (STIs) spread either by exposure to infected fluids or by direct contact with infected skin. Skin-to-skin STIs are spread from one person to another by skin-to-skin contact and can be transmitted without intercourse.

A few, such as pubic lice, can be spread by even more casual contact. However, STI transmission via clothing or other objects is relatively rare. STIs are also called sexually transmitted diseases (STDs).

This article discusses the STIs that can be spread via skin-to-skin contact and what their symptoms are. It also looks at skin symptoms that can occur with other common STIs.

What STIs Can Be Spread by Skin-to-Skin Contact?

Transmission via skin-to-skin contact is possible for several different infections. The STIs where skin-to-skin contact poses the biggest risk for transmission include the following:

Genital and Oral Herpes

Contact with very contagious herpes sores can transmit herpes from person to person.

In fact, most people living with oral herpes acquire the virus in childhood. Casual contact, such as with relatives, can lead to herpes transmission. Both HSV-1 and HSV-2 can be either oral or genital. However, HSV-2 is more often found in the genitals.

Symptoms

Herpes causes fluid-filled blisters to appear on the genitals, rectum, or mouth. These blisters break open, leaving painful, crusted sores behind. The sores can take up to four weeks to heal. If it's your first outbreak, you may also experience flu-like symptoms such as fever and body aches.

Human Papillomavirus (HPV)

Both cancer-causing HPV varieties and the HPV varieties that cause genital warts are easily transmitted through skin contact. Fortunately, vaccines can prevent this.

The most common cancer and wart-causing varieties can be prevented by early vaccination against HPV. However, ideally, vaccination should occur before people become sexually active. That's why initial vaccination is recommended at age 11 or earlier, though it is possible to get it later.

Symptoms

HPV does not always cause symptoms. This is why it spreads so easily; many people do not realize they carry the virus.

Genital warts appear as painless growths around the vagina or anus or on the penis. The warts may be flat or have a cauliflower-like appearance and may appear alone or in clusters. They don't usually hurt but some people do experience itching and/or irritation.

Syphilis

There is a growing concern about this disease spreading through contact with mouth sores during oral sex. Most people think of syphilis as an easily preventable disease. It can be in some situations but not in others.

A condom that covers a syphilis sore can help prevent the spread of this STI. However, sores in the mouth and on other parts of the body may go unrecognized and untreated. Those sores can still be contagious. That's why testing is still important for key populations.

Symptoms

Symptoms of syphilis appear in stages, which usually proceed as follows:

• Primary stage: The first sign of syphilis is usually a single lesion, called a chancre, though it is possible to develop more than one. The chancre is usually painless and feels firm and round. It appears on the part of the body where the syphilis bacteria first contacts the skin, such as inside the vagina or anus. The chancre will usually go away on its own with or without treatment in three to six weeks.
• Secondary stage: If the infection is not treated, it progresses to the secondary stage. In this stage, the infected person will develop a rough, red rash on the palms or the bottoms of the feet. The rash can sometimes also appear on other parts of the body. They may also develop lesions in the mucous membranes such as the vagina, anus, or mouth. Large, raised, gray, or white lesions called condyloma may appear in warm, moist parts of the body such as the mouth or armpits. Some people also have flu-like symptoms such as fever, sore throat, muscle aches, and fatigue.
• Latent stage: If the person does not receive treatment, the infection may progress to the latent stage. During this stage, the disease does not have any symptoms. It is possible to remain in the latent stage for years.
• Tertiary stage: This stage can occur decades after the initial infection. It can affect multiple body systems and organs including the heart, brain, eyes, and bones. Some people develop large lesions called gummas on the skin. The infection may reach the nervous system, causing symptoms like headache, muscle weakness, or dementia.
  

Molluscum Contagiosum (MC)

This skin disease is more often thought of as a disease of childhood than an STI. However, molluscum contagiosum sores can be transmitted during sex as well.

Although generally a painless infection, if the sores break open, they can become infected by other bacteria. Therefore, it's worth talking to a healthcare provider about treatment. You can also cover sores to prevent skin-to-skin contact since treatment can be difficult.

Symptoms

Molluscum contagiosum causes small bumps to appear on the skin. The bumps are usually a pearly pink, white, or flesh-color and have a dimple in the center. Some of these lesions can be as large as a pencil eraser, though most are much smaller. They may be itchy or sore.

Which STIs Affect the Skin?

Many common STIs can affect the skin, including some that are not spread through skin-to-skin contact. These infections can cause rashes, sores, and other lesions to appear on the skin. These STIs include:

• Human papillomavirus
• Herpes simplex virus
• Syphilis
• Molluscum contagiosum
  
• Gonorrhea
• Chlamydia
• HIV
  

Is It a Rash or an STI?

It is possible to develop a rash on the genitals that is not caused by a sexually transmitted infection. Rashes can have other causes such as a yeast infection or an irritation to soap or a skincare product. Sometimes it can be hard to tell the difference.

Some of the signs that a rash on or around the genitals may be caused by an STI include:

Abnormal Discharge

Discharge from the vagina or penis can be a sign of several different STIs, though discharge may also occur as a symptom of a yeast infection or other condition that is not transmitted through sex. For example:

• Yellow discharge from the vagina can be a symptom of chlamydia, though sometimes the infection does not cause any symptoms. Males may have a milky-colored discharge from the penis.
• A white, green, yellow, or blood-tinged discharge from the vagina or a thick yellow discharge from the penis can be a symptom of gonorrhea.

Bumps, Warts, or Rashes

Blisters or other flat or raised lesions can be a symptom of several different STIs. For example:

• Fluid-filled blisters that burst and crust over are a sign of herpes.
• Painless flat or cauliflower-like lesions that form alone or in clusters can be a sign of human papillomavirus.
• A firm, red, painless sore can be an early symptom of syphilis. People with syphilis may also develop a rash on the palms or soles of the feet or elsewhere on the body.
• Gonorrhea can cause a rash when it spreads to the bloodstream. A gonorrhea rash can appear as small red spots under the skin (petechiae), flat or elevated spots, or fluid-filled blisters.

Difficulty Urinating

Certain STIs can also cause pain or difficulty urinating, though this can vary from person to person. For example:

• Chlamydia may cause pain or burning with urination in both males and females.
• Both males and females can also experience pain with urination when infected with gonorrhea.
• During a herpes outbreak, broken sores can cause pain with urination.

Painful Intercourse

People who are infected with an STI may also experience pain during intercourse. Some of the conditions that cause this symptom include chlamydia, gonorrhea, and herpes, all of which can irritate the skin and cause pain during sexual contact.

Does Safer Sex Guarantee Safety?

STIs transmitted by skin-to-skin contact may be difficult to entirely prevent by safer sex. That's because barriers do not necessarily cover all potentially infectious skin.

Condoms and other barriers may prevent transmission of STIs such as HIV and gonorrhea that spread through bodily fluids. These STIs are spread by exposure to infected secretions such as blood, semen, and vaginal fluids. (Infectious secretions vary by disease.) Remember, though, HIV does not spread by casual contact or skin-to-skin contact.​

Summary

Some sexually transmitted infections can be spread through skin-to-skin contact. These include herpes, human papillomavirus, syphilis, and molluscum contagiosum. Other STIs that are spread through bodily fluids such as gonorrhea and HIV can cause skin symptoms like a rash or lesions.

It can be hard to tell the difference between an STI and skin rashes with other causes. Some symptoms common to STIs include discharge from the penis or vagina, bumps and other lesions, difficulty urinating, and pain with intercourse.