Not all STIs are symptomatic, and symptoms may not appear immediately after infection. In some instances a disease can be carried with no symptoms, which leaves a greater risk of passing the disease on to others. Depending on the disease, some untreated STIs can lead to infertility, chronic pain or even death.

The presence of an STI in prepubescent children may indicate sexual abuse.

Most people infected with trichomonas vaginalis do not have any symptoms and can be undetected for years. Symptoms experienced include pain, burning or itching in the penis, urethra (urethritis), or vagina (vaginitis). Discomfort for both sexes may increase during intercourse and urination. For women there may also be a yellow-green, itchy, frothy, foul-smelling ("fishy" smell) vaginal discharge. In rare cases, lower abdominal pain can occur. Symptoms usually appear within 5 to 28 days of exposure.

Sexually transmitted infections (STI), also referred to as sexually transmitted diseases (STD) and venereal diseases (VD), are infections that are commonly spread by sex, especially vaginal intercourse, anal sex or oral sex. Many times STIs initially do not cause symptoms. This results in a greater risk of passing the disease on to others. Symptoms and signs of disease may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. STIs can be transmitted to an infant before or during childbirth and may result in poor outcomes for the baby. Some STIs may cause problems with the ability to get pregnant.

More than 30 different bacteria, viruses, and parasites can be transmitted through sexual activity. Bacterial STIs include chlamydia, gonorrhea, and syphilis among others. Viral STIs include genital herpes, HIV/AIDS, and genital warts among others. Parasitic STIs include trichomoniasis among others. While usually spread by sex, some STIs can be spread by non-sexual contact with donor tissue, blood, breastfeeding, or during childbirth. STI diagnostic tests are usually easily available in the developed world, but this is often not the case in the developing world.

The most effective way of preventing STIs is by not having sex. Some vaccinations may also decrease the risk of certain infections including hepatitis B and some types of HPV. Safer sex practices such as use of condoms, having a smaller number of sexual partners, and being in a relationship where each person only has sex with the other also decreases the risk. Circumcision in males may be effective to prevent some infections. Most STIs are treatable or curable. Of the most common infections, syphilis, gonorrhea, chlamydia, trichomoniasis are curable, while herpes, hepatitis B, HIV/AIDS, and HPV are treatable but not curable. Resistance to certain antibiotics is developing among some organisms such as gonorrhea.

In 2015, about 1.1 billion people had STIs other than HIV/AIDS. About 500 million were infected with either syphilis, gonorrhea, chlamydia or trichomoniasis. At least an additional 530 million people have genital herpes and 290 million women have human papillomavirus. STIs other than HIV resulted in 108,000 deaths in 2015. In the United States there were 19 million new cases of sexually transmitted infections in 2010. Historical documentation of STIs date back to at least the Ebers papyrus around 1550 BC and the Old Testament. There is often shame and stigma associated with these infections. The term "sexually transmitted infection" is generally preferred over "sexually transmitted disease" or "venereal disease", as it includes those who do not have symptomatic disease.

These are only local and no systemic manifestations are present.

The ulcer characteristically:

- Ranges in size dramatically from 3 to 50 mm (1/8 inch to two inches) across

- Is painful

- Has sharply defined, undermined borders

- Has irregular or ragged borders

- Has a base that is covered with a gray or yellowish-gray material

- Has a base that bleeds easily if traumatized or scraped

- painful swollen lymph nodes occurs in 30 to 60% of patients.

- dysuria (pain with urination) and dyspareunia (pain with intercourse) in females

About half of infected men have only a single ulcer. Women frequently have four or more ulcers, with fewer symptoms.

The initial ulcer may be mistaken as a "hard" chancre, the typical sore of primary syphilis, as opposed to the "soft chancre" of chancroid.

Approximately one-third of the infected individuals will develop enlargements of the inguinal lymph nodes, the nodes located in the fold between the leg and the lower abdomen.

Half of those who develop swelling of the inguinal lymph nodes will progress to a point where the nodes rupture through the skin, producing draining abscesses. The swollen lymph nodes and abscesses are often referred to as buboes.

Trichomoniasis (trich) is an infectious disease caused by the parasite "Trichomonas vaginalis". About 70% of women and men do not have symptoms when infected. When symptoms do occur they typically begin 5 to 28 days after exposure. Symptoms can include itching in the genital area, a bad smelling thin vaginal discharge, burning with urination, and pain with sex. Having trichomoniasis increases the risk of getting HIV/AIDS. It may also cause complications during pregnancy.

Trichomoniasis is a sexually transmitted infection (STI) which is most often spread through vaginal, oral, or anal sex. It can also spread through genital touching. People who are infected may spread the disease even when symptoms are not present. Diagnosis is by finding the parasite in the vaginal fluid using a microscope, culturing the vagina or urine, or testing for the parasite's DNA. If present other sexually transmitted infections should be tested for.

Methods of prevention include not having sex, using condoms, not douching, and being tested for STIs before having sex with a new partner. Trichomoniasis can be cured with antibiotics, either metronidazole or tinidazole. Sexual partners should also be treated. About 20% of people get infected again within three months of treatment.

There were about 122 million new cases of trichomoniasis in 2015. In the United States there are about 2 million women affected. It occurs more often in women than men. "Trichomonas vaginalis" was first identified in 1836 by Alfred Donné. It was first recognized as causing this disease in 1916.

Chancroid ( ) (also known as soft chancre and ulcus molle) is a bacterial sexually transmitted infection characterized by painful sores on the genitalia. Chancroid is known to spread from one individual to another solely through sexual contact.

A genital ulcer is located on the genital area, usually caused by a sexually transmitted disease such as genital herpes, syphilis, chancroid, or "Chlamydia trachomatis". Some other signs of having genital ulcers include enlarged lymph nodes in the groin area, or vesicular lesions, which are small, elevated sores or blisters. The syndrome may be further classified into penile ulceration and vulval ulceration for males and females respectively.

Genital ulcers are not strictly a sign of an STD. They can occur in patients with Behcet's syndrome, lupus, and some forms of rheumatoid arthritis (all non-communicable diseases). Genital tuberculosis, often caused by direct genital contact with infected sputum, can also present as genital ulcer.

A male genital disease is a condition that affects the male reproductive system. An example is orchitis.

non infection disease

Genital warts may occur singly but are more often found in clusters. They may be found anywhere in the anal or genital area, and are frequently found on external surfaces of the body, including the penile shaft, scrotum, or labia majora of the vagina. They can also occur on internal surfaces like the opening to the urethra, inside the vagina, on the cervix, or in the anus.

They can be as small as 1-5mm in diameter, but can also grow or spread into large masses in the genital or anal area. In some cases they look like small stalks. They may be hard ("keratinized") or soft. Their color can be variable, and sometimes they may bleed.

In most cases, there are no symptoms of HPV infection other than the warts themselves. Sometimes warts may cause itching, redness, or discomfort, especially when they occur around the anus. Although they are usually without other physical symptoms, an outbreak of genital warts may cause psychological distress, such as anxiety, in some people.

Genital warts are symptoms of a contagious sexually transmitted disease caused by some types of human papillomavirus (HPV). Warts are the most easily recognized symptom of genital HPV infection. About 90% of those who contract HPV will not develop genital warts.

HPV types 6 and 11 are most frequently the cause of genital warts. It is spread through direct skin-to-skin contact, usually during oral, genital, or anal sex with an infected partner. While some types of HPV cause cervical cancer and anal cancers, these are not the same types of HPV that cause genital warts.

Some HPV vaccines includes coverage for types 6 and 11 and therefore can prevent genital warts. It is also possible to be infected with different types of HPV either at the same or different times.

Although estimates of the number of new cases a year vary, HPV is so common that nearly all sexually active people will get it at some point in their lives. A "condyloma acuminatum" is a single genital wart, and "condylomata acuminata" are multiple genital warts. The word roots mean "pointed wart" (from Greek κόνδυλος, "knuckle", Greek -ωμα "", "disease," and Latin "" "pointed"). Although similarly named, it is not the same as condyloma latum, which is a complication of secondary syphilis.

The initial period following the contraction of HIV is called acute HIV, primary HIV or acute retroviral syndrome. Many individuals develop an influenza-like illness or a mononucleosis-like illness 2–4 weeks post exposure while others have no significant symptoms. Symptoms occur in 40–90% of cases and most commonly include fever, large tender lymph nodes, throat inflammation, a rash, headache, and/or sores of the mouth and genitals. The rash, which occurs in 20–50% of cases, presents itself on the trunk and is maculopapular, classically. Some people also develop opportunistic infections at this stage. Gastrointestinal symptoms, such as vomiting or diarrhea may occur. Neurological symptoms of peripheral neuropathy or Guillain–Barré syndrome also occurs. The duration of the symptoms varies, but is usually one or two weeks.

Due to their nonspecific character, these symptoms are not often recognized as signs of HIV infection. Even cases that do get seen by a family doctor or a hospital are often misdiagnosed as one of the many common infectious diseases with overlapping symptoms. Thus, it is recommended that HIV be considered in people presenting an unexplained fever who may have risk factors for the infection.

There are three main stages of HIV infection: acute infection, clinical latency and AIDS.

MAGI includes infections (bacterial, viral, fungal etc) involving one or more of the following male genital organs or tracts:

- seminal vesicles (seminal vesiculitis)

- prostate gland (prostatitis)

- vas deferens

- epididymis (epididymitis)

- testicles (orchitis)

- urethra (urethritis)

- Cowper's glands

Potential complications include:

- obstruction of the epididymis

- impairment of spermatogenesis

- impairmentment of sperm function

- induction of sperm auto-antibodies

- dysfunctions of the male accessory glands

These complications can result in

sexual dysfunction and male subfertility.

Common symptoms include increased vaginal discharge that usually smells like fish. The discharge is often white or gray in color. There may be burning with urination. Occasionally, there may be no symptoms.

The discharge coats the walls of the vagina, and is usually without significant irritation, pain, or erythema (redness), although mild itching can sometimes occur. By contrast, the normal vaginal discharge will vary in consistency and amount throughout the menstrual cycle and is at its clearest at ovulation—about two weeks before the period starts. Some practitioners claim that BV can be asymptomatic in almost half of affected women, though others argue that this is often a misdiagnosis.

Skin infection ("cutaneous" infection) with HPV is very widespread.

Skin infections with HPV can cause noncancerous skin growths called warts (verrucae). Warts are caused by a rapid growth of cells on the outer layer of the skin.

While cases of warts have been described since the time of ancient Greece, their viral cause was not known until 1907.

Skin warts are most common in childhood and typically appear and regress spontaneously over the course of weeks to months. About 10% of adults also suffer from recurring skin warts. All HPVs are believed to be capable of establishing long-term "latent" infections in small numbers of stem cells present in the skin. Although these latent infections may never be fully eradicated, immunological control is thought to block the appearance of symptoms such as warts. Immunological control is HPV type-specific, meaning an individual may become resistant to one HPV type while remaining susceptible to other types. In one study, infection by HPV types 2, 27, and 57 was found in people with warts, while infection by HPV types 1, 2, 63, and 27 was found in people with clinically normal skin.

Types of warts include:

- Common warts are usually found on the hands and feet, but can also occur in other areas, such as the elbows or knees. Common warts have a characteristic cauliflower-like surface and are typically slightly raised above the surrounding skin. Cutaneous HPV types can cause genital warts but are not associated with the development of cancer.

- Plantar warts are found on the soles of the feet; they grow inward, generally causing pain when walking.

- Subungual or periungual warts form under the fingernail (subungual), around the fingernail, or on the cuticle (periungual). They are more difficult to treat than warts in other locations.

- Flat warts are most commonly found on the arms, face, or forehead. Like common warts, flat warts occur most frequently in children and teens. In people with normal immune function, flat warts are not associated with the development of cancer.

Genital warts are quite contagious, while common, flat, and plantar warts are much less likely to spread from person to person.

In males, the lesions occur on the glans penis, shaft of the penis or other parts of the genital region, on the inner thigh, buttocks, or anus. In females, lesions appear on or near the pubis, clitoris or other parts of the vulva, buttocks or anus.

Other common symptoms include pain, itching, and burning. Less frequent, yet still common, symptoms include discharge from the penis or vagina, fever, headache, muscle pain (myalgia), swollen and enlarged lymph nodes and malaise. Women often experience additional symptoms that include painful urination (dysuria) and cervicitis. Herpetic proctitis (inflammation of the anus and rectum) is common for individuals participating in anal intercourse.

After 2–3 weeks, existing lesions progress into ulcers and then crust and heal, although lesions on mucosal surfaces may never form crusts. In rare cases, involvement of the sacral region of the spinal cord can cause acute urinary retention and one-sided symptoms and signs of myeloradiculitis (a combination of myelitis and radiculitis): pain, sensory loss, abnormal sensations (paresthesia) and rash. Historically, this has been termed Elsberg syndrome, although this entity is not clearly defined.

Bacterial vaginosis (BV) is a disease of the vagina caused by excessive growth of bacteria. Common symptoms include increased vaginal discharge that often smells like fish. The discharge is usually white or gray in color. Burning with urination may occur. Itching is uncommon. Occasionally, there may be no symptoms. Having BV approximately doubles the risk of infection by a number of other sexually transmitted infections, including HIV/AIDS. It also increases the risk of early delivery among pregnant women.

BV is caused by an imbalance of the naturally occurring bacteria in the vagina. There is a change in the most common type of bacteria and a hundred to thousandfold increase in total numbers of bacteria present. Typically, bacteria other than "Lactobacilli" become more common. Risk factors include douching, new or multiple sex partners, antibiotics, and using an intrauterine device, among others. However, it is not considered a sexually transmitted infection. Diagnosis is suspected based on the symptoms, and may be verified by testing the vaginal discharge and finding a higher than normal vaginal pH, and large numbers of bacteria. BV is often confused with a vaginal yeast infection or infection with Trichomonas.

Usually treatment is with an antibiotic, such as clindamycin or metronidazole. These medications may also be used in the second or third trimesters of pregnancy. However, the condition often recurs following treatment. Probiotics may help prevent re-occurrence. It is unclear if the use of probiotics or antibiotics affects pregnancy outcomes.

BV is the most common vaginal infection in women of reproductive age. The percentage of women affected at any given time varies between 5% and 70%. BV is most common in parts of Africa and least common in Asia and Europe. In the United States about 30% of women between the ages of 14 and 49 are affected. Rates vary considerably between ethnic groups within a country. While BV like symptoms have been described for much of recorded history, the first clearly documented case occurred in 1894.

Over 170 types of HPV have been identified, and they are designated by numbers.

Some HPV types, such as HPV-5, may establish infections that persist for the lifetime of the individual without ever manifesting any clinical symptoms. HPV types 1 and 2 can cause common warts in some infected individuals. HPV types 6 and 11 can cause genital warts and laryngeal papillomatosis.

HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, and 82 are considered carcinogenic.

This table lists common symptoms of HPV infection and associated strains of HPV:

Genital herpes is an infection by herpes simplex virus (HSV) of the genitals. Most people either have no or mild symptoms and thus do not know they are infected. When symptoms do occur, they typically include small blisters that break open to form painful ulcers. Flu-like symptoms may also occur. Onset is typically around 4 days after exposure with symptoms lasting up to 4 weeks. Once infected further outbreaks may occur but are generally milder.

The disease is typically spread by direct genital contact with the skin surface or secretions of someone who is infected. This may occur during sex including oral sex. Active sores are not required for transmission to occur. HSV is classified into two types, HSV-1 and HSV-2. While historically mostly cause by HSV-2, genital HSV-1 has become more common in the developed world. Diagnosis may occur by testing lesions using either PCR or viral culture or blood tests for specific antibodies.

Efforts to prevent infection include not having sex, using condoms, and only having sex with someone who is not infected. Once infected their is no cure. Antiviral medications may, however, prevent outbreaks or shorten outbreaks if they occur. The long term use of antivirals may also decrease the risk of further spread.

In 2015 about 846 million people (12%) had genital herpes. Women are more commonly infected than men. Rates of disease caused by HSV-2 have decreased in the United States between 1990 and 2010. Complications may rarely include aseptic meningitis, an increased risk of HIV/AIDS if exposed, and spread to the baby during childbirth resulting in neonatal herpes.

A female genital disease is a condition that affects the female reproductive system.

Warts are typically small, rough, and hard growths that are similar in color to the rest of the skin. They typically do not result in symptoms except when on the bottom of the feet where they may be painful. While they usually occur on the hands and feet they can also affect other locations. One or many warts may appear. They are not cancerous.

Warts are caused by infection with a type of human papillomavirus (HPV). Factors that increase the risk include use of public showers, working with meat, eczema, and a low immune system. The virus is believed to enter the body through skin that has been damaged slightly. A number of types exist including: common warts, plantar warts, filiform warts, and genital warts. Genital warts are often sexually transmitted.

Without treatment, most types of warts resolve in months to years. A number of treatments may speed resolution including salicylic acid applied to the skin and cryotherapy. In those who are otherwise healthy they do not typically result in significant problems. Treatment of genital warts differs from that of other types.

Warts are very common, with most people being infected at some point in their life. The estimated current rate of non-genital warts among the general population is 1–13%. They are more common among young people. Estimated rates of genital warts in sexually active women is 12%. Warts have been described at least as far back as 400 BC by Hippocrates.

A range of types of wart have been identified, varying in shape and site affected, as well as the type of human papillomavirus involved. These include:

- Common wart ("Verruca vulgaris"), a raised wart with roughened surface, most common on hands, but can grow anywhere on the body. Sometimes known as a Palmer wart or Junior wart.

- Flat wart ("Verruca plana"), a small, smooth flattened wart, flesh-coloured, which can occur in large numbers; most common on the face, neck, hands, wrists and knees.

- Filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips.

- Genital wart (venereal wart, "Condyloma acuminatum", "Verruca acuminata"), a wart that occurs on the genitalia.

- Mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet.

- Periungual wart, a cauliflower-like cluster of warts that occurs around the nails.

- Plantar wart (verruca, "Verruca plantaris"), a hard sometimes painful lump, often with multiple black specks in the center; usually only found on pressure points on the soles of the feet.

Alternatively, female genital diseases can be more strictly classified by location of the disease, which, in turn, can be broadly divided between diseases that affect the female internal genitalia and those that affect the female external genitalia.

Lipschütz ulcer, ulcus vulvae acutum or reactive non-sexually related acute genital ulcers () is a rare disease characterized by painful genital ulcers, fever, and lymphadenopathy, occurring most commonly, but not exclusively, in adolescents and young women. Previously, it was described as being more common in virgins. It is not a sexually transmitted disease, and is often misdiagnosed, sometimes as a symptom of Behçet's disease.

Lipschütz ulcer is named after Benjamin Lipschütz, who first described it in 1912. The cause is still unknown, although it has been associated with several infectious causes, including paratyphoid fever, cytomegalovirus, "Mycoplasma pneumoniae" and Epstein-Barr virus infection