Vaginal Infection, Trichomonas vaginitis, Trich, Trichomonal Vaginitis

What is Trichomoniasis?

Trichomoniasis is a sexually transmitted disease (STD) caused by a parasite that is passed from one person to another through sexual contact or through contact with damp objects that contain the parasite. Also known as “trich” or “trick,” it does not pose a major health risk, but can be uncomfortable for those who are infected.

Trichomoniasis infects 7.4 million women and men every year, according to the U.S. Centers for Disease Control and Prevention (CDC). The illness is relatively rare in men and more common in women. In fact, trichomoniasis is the most common, curable STD in young women and affects about 5 to 10 percent of all women, according to the National Women’s Health Resource Center. In addition, some studies have found that up to 50 percent of women infected with other STDs are also infected with trichomoniasis.

A single-celled protozoan parasite called Trichomonas vaginalis causes trichomoniasis. This parasite has a tail resembling a whip that it uses to propel itself through vaginal and urethral mucus. The vagina is the most common site of infection in women, while the urethra is the most common site of infection in men. The parasite that causes trichomoniasis cannot survive in the mouth or rectum.

Women can develop trichomoniasis after sexual contact with infected men or women – e.g., through penis-to-vagina or vulva-to-vulva contact. Infection can also be spread through oral or possibly anal sex. In addition, a woman can become infected if her genitals come into contact with certain objects that contain the parasite. These objects include toilet seats, damp towels or washcloths and wet clothing, such as swimsuits.

Infection is most commonly transmitted during vaginal intercourse. Men usually contract the infection from sexual contact with an infected woman.

Trichomoniasis is considered one of the three main causes of vaginitis. However, many women with trichomoniasis do not experience the symptoms of vaginitis (e.g., burning sensation, discomfort during urination). However, even if no symptoms are present, people with trichomoniasis can still pass the disease on to others.

A trichomoniasis infection makes a person more vulnerable to other STDs, including the human immunodeficiency virus (HIV). A trichomoniasis infection stimulates the immune system, resulting in higher production of the immune system response cells that the HIV virus targets. In addition, women who have both HIV and trichomoniasis are more likely to infect their partners with HIV.

Prolonged infection in women also can cause changes in cervical surface tissues. Complications of trichomoniasis in men include prostatitis (inflammation of the prostate) or epididymitis (inflammation of the tubes that carry and store sperm).

Pregnant women who are infected with trichomoniasis may experience premature labor and delivery, and may give birth to babies who have low birth weight (less than 5 pounds). For this reason, it is important for pregnant women to inform their physician if they are experiencing symptoms of infection.

Signs and symptoms of trichomoniasis

About one-third to one-half of women infected with trichomoniasis experience no symptoms, according to the National Women’s Health Resource Center. However, other women do experience symptoms, usually between 5 and 28 days after exposure.

These symptoms may include:

  • Inflammation, irritation and itching in the genital area (vaginitis).
  • Yellow, green or gray vaginal discharge. This is often thick and foamy and sometimes has a strong "fish-like" odor.
  • Discomfort during sexual intercourse or during urination.
  • Soreness or itching of the labia (the “lips” near the entrance to the vagina) and inner thighs. The labia may also be swollen.
  • Lower abdominal pain (in rare cases).
  • Although not visible to the patient, some women may have small red sores in the vagina or on the cervix.

Most men infected with trichomoniasis do not experience symptoms. In some cases, men may have urethritis (inflammation of the urethra), itching of the urethra, dysuria (difficulty or pain during urination) or a slight discharge from the penis. Some men also may experience a slight burning following urination or ejaculation.

A man’s symptoms may disappear after about a week or so, even if he has not received treatment. However, men whose trichomoniasis infections are not treated can continue to infect others until they receive treatment.

Women and men who have any of the symptoms associated with trichomoniasis are urged to refrain from having sexual relations until their condition is diagnosed and treated.

Diagnosis methods for trichomoniasis

To diagnose trichomoniasis, a physician will compile a patient’s medical history and perform a complete physical examination. Female patients will undergo a pelvic examination, during which the physician will open the walls of the vagina and look for small red sores inside the vagina or on the cervix.

A sample of vaginal fluid will be obtained and examined under a microscope to determine the presence of parasites. Additional tests that may be performed include a vaginal culture or DNA test. Physicians frequently also perform tests for other sexually transmitted diseases (STDs) such as gonorrhea and chlamydia, which may accompany trichomoniasis. A Pap smear may be performed to look for changes in cervical surface tissues that are sometimes associated with a prolonged trichomoniasis infection.

Trichomoniasis is often more difficult to diagnose in male patients. Special culture techniques may be necessary to make a definitive diagnosis. Male sexual partners of females infected with trichomoniasis are often assumed to be infected as well.

Treatment options for trichomoniasis

In most cases, trichomoniasis is treated with a single oral dose of the prescription drug metronidazole which is used to treat bacterial, fungal and parasitic infections. If this fails to cure the infection, a longer treatment regimen of three to five days may be required.

In 2004, the U.S. Food and Drug Administration (FDA) approved another drug, tinidazole, to treat trichomoniasis and other protozoa infections. This drug is now being used in patients who fail to respond to treatment with metronidazole.

Unlike some sexually transmitted diseases, trichomoniasis has not developed strains that are resistant to medications, so the prognosis for patients who take these medications is excellent. In about 5 percent of cases, women do not respond to standard treatments. In such situations, an allergy to the medication may be to blame for the lack of success.

Patients who are allergic to metronidazole or tinidazole may receive a prescription for a topical medication called paromomycin. While topical medications may reduce symptoms, they usually are less effective than metronidazole or tinidazole and may not cure the infection.

The U.S. Centers for Disease Control and Prevention recommends that both partners receive treatment if one partner has been diagnosed with trichomoniasis. This will ensure that any traces of the parasite in either partner are eliminated and will not be further transmitted. Patients should refrain from sexual activity while they are being treated or until their symptoms subside.

Women should not take medications commonly used for this condition during the first three months of pregnancy, according to the FDA. However, after the first trimester, metronidazole or tinidazole may be taken if necessary. The National Women’s Health Information Center suggests treating pregnant women who have symptoms and not treating those who have no symptoms.

Prevention methods for trichomoniasis

There is no medication in the United States that may help prevent trichomoniasis. In Europe, however, a vaccine for trichomoniasis has been marketed but has proven to be largely ineffective.

Having contracted trichomoniasis does not provide immunity against future infection. People who are successfully treated for trichomoniasis can become infected again if they are exposed to the parasite that causes the condition.

Certain preventive measures may help to reduce the risk of contracting trichomoniasis.

These include:

  • Refrain from having sexual intercourse. Complete abstinence (refraining from vaginal, anal and oral sex) is the best way to prevent becoming infected with trichomoniasis.
  • Limit sexual activity to one partner. Restricting sexual relations to just one partner who is known to be free from infection can significantly reduce the risk of contracting trichomoniasis.
  • Use condoms. Use of condoms during vaginal, anal and oral sex can substantially reduce (but not eliminate) the risk of contracting trichomoniasis. Condoms must be used every time a person has sex. Male latex condoms or female polyurethane condoms should be used during vaginal sex. Male condoms should be used during anal sex, and a rubber material known as a dental dam should be used during oral sex. Although female condoms and dental dams offer some protection against sexually transmitted diseases, they are not as effective as male latex condoms.
  • Do not share swimsuits, towels, washcloths, bath sponges, loofahs or bath brushes. The trichomoniasis parasite can live outside the body for as long as 45 minutes and can be transmitted to someone whose genitals come in contact with damp objects that have the parasite on them.
  • Exercise caution when using public restrooms because trichomoniasis can be transmitted through brief contact with a toilet seat that contains the parasite that causes trichomoniasis. Refrain from sitting directly on public toilet seats or use a protective paper sheet before sitting on the seat.

Questions for your doctor about trichomoniasis

Preparing questions in advance can help patients to have more meaningful discussions with their physician regarding their conditions. Patients may wish to ask their doctor the following questions related to trichomoniasis:

  • How did I get trichomoniasis?
  • How do you know my symptoms are not due to another STD or medical condition?
  • How soon will I get the results of my test for this condition?
  • What type of medication will you prescribe for my condition?
  • How long will I need the medication?
  • For how long will I be contagious?
  • How will I know my trichomoniasis is cured?
  • When can I resume sexual activity?
  • Am I likely to be reinfected with trichomoniasis in the future?
  • Do my current and past sexual partners need to be tested and treated for this disease?

Additional Information


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Avoid overexertion, heat and excessive sweating. Delay sexual relations until you are well. Allow about 10 days for recovery.

What might complicate it?

The development of drug resistant strains has been reported, and infection with these strains may lead to chronic trichomoniasis. Chronic trichomoniasis may cause cellular changes that can be misinterpreted on Pap smear.

Predicted outcome

The prognosis for treated trichomoniasis is excellent. But, if any sexual partner(s) is not treated, reinfection is likely.


Various bacterial and chlamydial infections of the urinary and genital systems may give similar symptoms. Pelvic inflammatory disease may also present with a similar history.

Appropriate specialists

Gynecologist, urologist, and infectious disease specialist.

Notify your physician if

  • You or a family member has symptoms of trichomonal vaginitis.
  • Symptoms persist longer than 1 week or worsen, despite treatment.
  • Unusual vaginal bleeding or swelling develops.
  • After treatment, symptoms recur.