This page is general health information, not medical advice. It cannot tell you whether you have an infection. A clinician can, and the testing options on this site are a good place to start.

Trichomoniasis is the most common curable sexually transmitted infection, according to the CDC. It is also one of the least talked about. Many people who have it notice nothing at all.

This guide explains the organism behind it, what research suggests about how it behaves, what trichomoniasis symptoms can look like, how testing works, and what clinicians prescribe. It also covers where to get tested in San Antonio.

What trichomoniasis is

Trichomoniasis is caused by Trichomonas vaginalis, a single-celled parasite. It is not a bacterium or a virus. That matters because it is treated with a different kind of medicine than chlamydia or gonorrhea.

The CDC says it spreads through genital contact, including vulva-to-penis, vulva-to-vulva and penis-to-penis contact. It does not require ejaculation. It is not spread by toilet seats, shared towels or casual contact.

Anyone who is sexually active can get it, whatever their gender or orientation. Having it says nothing about a person's character. The CDC estimates millions of infections in the United States at any given time, which is why clinicians treat it as a routine part of sexual health care.

The science: how the organism works

Biology and key features

Research on T. vaginalis describes a pear-shaped, flagellated cell that moves with whip-like tails and attaches to the lining of the genital tract. It lives only in humans. It does not survive well outside the body.

Unlike most human cells, it has no mitochondria. Research suggests it uses structures called hydrogenosomes to make energy without oxygen. This detail turns out to matter for treatment, as the next sections explain.

What research suggests about how it causes irritation

Laboratory studies suggest the parasite sticks to the surface cells of the vagina, cervix or urethra. Researchers have observed that it can release enzymes and other proteins that may damage cells and set off inflammation. That inflammation is one proposed reason for itching, burning and discharge.

Studies also suggest the parasite can change the balance of the vaginal microbiome. These are laboratory and observational findings. They help explain symptoms, but they do not predict what any one person will experience.

Links to other health outcomes

The CDC notes that trichomoniasis in pregnancy has been associated with preterm birth and low birth weight. The CDC also notes that the inflammation it causes may make it easier to acquire or pass on HIV. Observational studies show an association. They do not show that trichomoniasis alone causes these outcomes.

These links are one reason clinicians take a positive result seriously, and one reason treatment and retesting are worth finishing.

Trichomoniasis symptoms

The CDC says most people with trichomoniasis do not have symptoms. When symptoms do occur, they usually start within a few weeks of contact, but they can also appear much later.

In people with a vagina

The CDC lists these possible signs:

Vaginal discharge that may be thin or frothy and may look clear, white, yellow or green
An unusual or strong vaginal odor
Itching, burning, redness or soreness of the genitals
Discomfort when urinating
Discomfort during sex

In people with a penis

The CDC says symptoms are less common and may include:

Itching or irritation inside the penis
Burning after urination or ejaculation
Discharge from the penis

Why symptoms alone are not enough

These signs overlap with bacterial vaginosis, yeast infections, chlamydia, gonorrhea and non-sexual irritation. The CDC treatment guidelines point out that diagnosing by symptoms or by looking at a sample under a microscope can miss infections. Only a test can show whether the parasite is present, and a clinician is the right person to interpret the result.

If you notice any of the changes above, or if a partner has told you they were diagnosed, a test is a reasonable next step. Because many infections cause no symptoms, a test can also make sense without any signs at all.

Testing: what the CDC recommends

The CDC STI Treatment Guidelines (2021) recommend nucleic acid amplification tests, called NAATs, as a highly sensitive way to detect T. vaginalis. A NAAT looks for the parasite's genetic material, so it can find small amounts that other methods may miss.

Sample types

According to the CDC guidelines, the sample depends on anatomy:

For women, a vaginal swab is preferred. Endocervical swabs and urine can also be used.
For men, urine is generally the sample used. A urethral swab may also be an option.

The CDC notes that NAAT is the recommended test for people of all genders, and that some clinics use other tests, such as rapid antigen tests, when NAAT is not available. Ask the clinic which test it uses.

Who is tested

The CDC recommends testing people with symptoms. It also recommends testing women with HIV when they enter care and at least once a year after that. The guidelines say clinicians may consider screening for women in settings or groups with higher rates of trichomoniasis. Your clinician can tell you whether a test fits your situation.

Quality indicators for a good test visit

In place of product sourcing, here is what to look for in a testing visit. Research and CDC guidance suggest these markers of quality:

The clinic says which infections the visit includes. A routine panel does not always cover trichomoniasis, so it is fine to ask for it by name.
The clinic uses a NAAT where one is available, or tells you what it uses instead.
You get a clear explanation of how and when results will arrive.
A clinician reviews positive results with you and explains the next step.

The CDC also runs a national locator at gettested.cdc.gov, where you can look up testing sites by ZIP code. It is a good second place to check alongside the local list below.

Trichomoniasis treatment

Trichomoniasis is curable. Treatment is a prescription from a clinician. It is not something to buy over the counter or to treat with home remedies.

The CDC guidelines recommend a prescription antimicrobial from the nitroimidazole family. The clinician chooses the specific medicine and how long to take it based on your sex, health history and any other conditions. The regimen can differ between people, so follow the instructions you are given.

How the medicine is thought to work

Research suggests nitroimidazoles are taken up by the parasite and activated inside those oxygen-free hydrogenosomes. The activated form is thought to damage the parasite's DNA. Human cells lack this activation step, which is one reason the medicine is considered selective. This is the proposed mechanism, based on laboratory studies.

Safety profile and contraindications

Clinicians weigh several things before prescribing. Points the CDC and prescribing information raise include:

Allergy: Tell the clinician about any past reaction to metronidazole, tinidazole or similar medicines. The CDC guidelines describe alternatives and specialist consultation for people who are allergic.
Alcohol: The prescribing information for these medicines warns about drinking alcohol during and for a period after treatment. Ask your clinician or pharmacist exactly how long to wait.
Other medicines: Some prescriptions and supplements interact with nitroimidazoles. Give the clinician your full list.
Pregnancy and breastfeeding: The CDC addresses treatment in pregnancy in its guidelines, and the advice for breastfeeding can differ by medicine. Tell the clinician if you are pregnant or nursing.
Common side effects: Research and labeling mention an upset stomach and a metallic taste. Call the clinic or pharmacy about anything that worries you.

The CDC also notes that reduced susceptibility to these medicines is reported in a small share of cases. If symptoms or a positive test persist after treatment, a clinician can look at next steps, including further testing.

Retesting and partners

Retesting

Reinfection is common. The CDC recommends that sexually active women be retested within three months after treatment, whether or not they have symptoms. A clinician can tell you whether retesting makes sense for you if you are not a woman. Retesting is a routine part of care, not a sign that something went wrong.

Partners

The CDC says current sex partners should be evaluated and treated, because treating only one person often leads to passing it back and forth. It advises waiting to have sex until you and your partners have all finished treatment and any symptoms have gone away.

Texas has a rule that can help here. The CDC's page on the legal status of expedited partner therapy in Texas says that Texas Medical Board rules do not require a physician to have a practitioner-patient relationship with a partner in order to prescribe STD medications for the partner of an established patient. Pharmacists may fill these prescriptions without the partner's name on the label. Ask your clinician whether this option fits your situation, since a clinician makes that call.

A message to a partner can be simple and factual: "I was diagnosed with trichomoniasis. It is curable, and you should get tested and treated."

Where to get tested in San Antonio

The San Antonio Metropolitan Health District (Metro Health) and several community organizations offer STI testing. The full local list is on our San Antonio clinic list. Here is what each source says about its services.

One caution applies to almost every site. The service pages below name tests for HIV, syphilis, gonorrhea, chlamydia and sometimes hepatitis C. None of the pages describes testing for trichomoniasis by name. Call first and ask whether the visit can include it.

Metro Health STI Walk-In Clinic

Metro Health runs a walk-in clinic at 512 E. Highland, Suite 150, San Antonio, TX 78210. The phone number is 210-207-8830. Metro Health's page lists these details:

Hours: Monday to Thursday, 7:45 a.m. to 4:30 p.m., with the latest check-in at 3 p.m. Friday, 7:45 a.m. to noon, with the latest check-in at 10:30 a.m. Check-in may close early when the clinic is at capacity.
Cost: a $15 office visit administrative fee. Other fees vary by service.
Who it serves: residents of San Antonio and Bexar County and people with no other way to get STI services.
Requirements: a photo ID. The clinic does not offer anonymous testing.

University Health describes the clinic as offering STI and HIV testing, treatment and counseling. That makes it a practical place to ask about both testing and a prescription in one visit.

Free community testing

San Antonio AIDS Foundation: 818 E. Grayson Street, (210) 225-4715. Its testing page lists free rapid HIV, syphilis, gonorrhea and chlamydia testing with no appointment needed.
Alamo Area Resource Center: 303 N. Frio, (210) 625-7200. Its page lists free testing for HIV, hepatitis C, syphilis, gonorrhea and chlamydia, with walk-ins Monday to Friday from 8 a.m. to 4:30 p.m. and on Wednesday until 8 p.m.
Kind Clinic: 730 Isom Road. The clinic lists HIV and STI testing and STI treatment, and its blog describes free walk-in testing. The location page does not give a clinic-specific phone number, so call the general support line at 833-937-5463 for details.
BEAT AIDS: 210.212.2266. The organization lists free, confidential STI testing and treatment. Its site does not say which location does the testing, so call before you go.

Sliding-scale clinics

CommuniCare Apollo Wellness Clinic: 6511 W Loop 1604 N, Ste. 105, (726) 224-3438, Monday to Friday, 8 a.m. to 5 p.m. CommuniCare offers a sliding fee discount for self-pay patients with family income under 200% of the federal poverty guidelines.
CentroMed: 210-922-7000. CentroMed lists screening and treatment for sexually transmitted diseases and uses a sliding fee scale based on income and family size. The page does not list a specific clinic address for these services, so call to ask.

Mailed kits

Texas DSHS runs Test for Texas, a free mailed at-home program for people 13 and older. Its listed tests are HIV, syphilis, gonorrhea and chlamydia. Trichomoniasis is not among them, so a kit does not replace an in-person visit if you want that test.

You can also use the CDC locator at gettested.cdc.gov for more options. For a wider overview of the city, see our guide to where to get tested for STDs in San Antonio.

Testing for more than one infection

Trichomoniasis often shows up alongside other infections, and the symptoms overlap. If you are getting tested for one, asking about the full range of STIs is reasonable. Our guide to chlamydia symptoms, testing and treatment in San Antonio covers a close neighbor on the testing menu.

For local context, the Texas Department of State Health Services reported 12,305 chlamydia cases and 5,983 gonorrhea cases in Bexar County in 2022. The sources reviewed for this guide do not publish a San Antonio figure for trichomoniasis, so check with Metro Health for local data.

Privacy and young people

Texas Family Code Section 32.003 lets a minor of any age consent to diagnosis and treatment of a reportable infectious or communicable disease, and parent or guardian consent is not required. The same section says a physician may tell a parent or guardian about the treatment. A clinic cannot promise that parents will never be told, so ask about its policy before the visit.

Key takeaways

Trichomoniasis is curable, and treatment is a prescription from a clinician.
Most people have no symptoms, so a NAAT is the most reliable way to find out.
Retesting within three months is recommended by the CDC for sexually active women.
Partners need attention too, and Texas rules allow some partner prescribing.
In San Antonio, call a clinic first and ask whether trichomoniasis is part of the visit.

Trichomoniasis: Symptoms, Testing and Treatment in San Antonio