Trichomoniasis, known as trich, is a common sexually transmitted disease (STD). It is caused by the parasite Trichomonas vaginalis, which, like all parasites, uses the host body in which it lives for food. It can cause vaginal inflammation in women and painful urination in men. By some estimates, millions of people have trichomoniasis, but only about a third of them have any symptoms. Experts estimate that at least one out of four new infections occurs in teen girls.

This STD is not a life-threatening illness, and it is easy to cure. But it's important to get it treated right away, because trichomoniasis can make it easier for a teenage girl or woman to contract HIV during sex. (In pregnant women, the infection is associated with preterm birth and smaller-than-normal babies, which are linked to health problems in newborns.)

Trichomoniasis is passed from one person to another through unprotected sexual contact. Men and women can both get this infection. Women are most likely to contract an infection in their vagina or vulva; men are usually infected in their urethra, the tube inside the penis through which they urinate.

Signs and symptoms

Most people who have a trichomoniasis infection don't have symptoms. If symptoms occur, they may begin anywhere from a few days to months after infection.

Symptoms in women:

  • Itching or irritation in the vagina 

  • A bad-smelling discharge that is frothy and yellow or greenish

  • Burning sensation in the vagina

Symptoms in men:

  • Irritation and itching in the penis

  • A discharge of pus from the penis 

Symptoms in both:

  • Pain or discomfort with urination and during sexual intercourse

Without treatment, the infection can linger for years.

When to call a doctor

Call the doctor if your child or teen is experiencing the above symptoms. If your child is an older teen girl, your health care provider may refer her to a gynecologist for testing and treatment.


At the doctor's office, the diagnosis may be made by:

  • Taking your child's temperature and blood pressure.

  • Physical examination, examination of genitals, and, in females, an internal pelvic exam to look for small red sores in the vagina.

  • Discussion of symptoms and you and your child's observations.

  • Taking samples to analyze for the presence of infection. Swabs of the urethra or vagina may be needed to get these samples. Teenagers often find these exams uncomfortable; some data suggest that teenage women are able to accurately collect samples themselves for lab testing.

  • Discussion of sexual activity. Although sexually transmitted infections are common among teens that are sexually active by choice, they also occur among children and teens that have been abused. Your teen's doctor or nurse may ask questions about your child's sexual history. If you suspect abuse, ask for help.


Treatment of trichomoniasis includes:

  • Prescription medication. Your teen's doctor may recommend an antibiotic to treat the infection. She should tell doctor if she is pregnant or suspects she might be, because metronidazole, one of the drugs used to treat trich, should be avoided during the first trimester of pregnancy. She should be sure to take all the medication as prescribed, even if she feels better.

  • Avoiding reinfection. One in five people gets the infection again after being treated. Your teen's partner should be treated at the same time, and both of them should avoid sexual intercourse until the treatment is finished and the symptoms have gone away. 

  • Preventing future infections. Learning about abstinence or safe, protected sex is also important.


The safe sex habits that your child needs to prevent trichomoniasis are the same ones that can prevent any STD. Consider this conversation about prevention to be your opportunity to reinforce your values with respect to sexual activity and protection. Important prevention tips are:

  • Abstinence. The best way to avoid trichomoniasis and other STDs is to not have sex.

  • Talk about sexual histories. Teach your child that if she is planning to have sex with someone, she should find out about her partner's sexual history. Agreeing to get tested for STDs together, before having sex, would be ideal.

  • Protected sex. Talk with your teen about how to have safe and protected sex. He or she should always use a new, latex condom for sexual intercourse to prevent infection. Condoms may not protect against all trichomoniasis infections, however. Remind teens that IUDs, shots, a diaphragm, spermicides, douching, and oral contraceptives like the pill do not prevent infection.

  • Say no to unwanted sex. Remind your child that she does not have to have sex or accept any unwanted sexual contact from anyone. It's important to report rape or abuse if it happens.

  • Report any unusual symptoms. If your teen again experiences unusual itching or burning in the genitals, it's important to see the doctor right away—this could be a sign of reinfection. Make sure your child has regular doctor's appointments and pelvic exams. Even if she seems completely healthy, regular exams are a good way to detect any problems.

For more information or to schedule an appointment, call 314.454.5437 or 800.678.5437 or email us.