Trichomoniasis is not a yeast infection. They are two completely different conditions caused by different organisms, spread in different ways, and requiring different treatments. Trichomoniasis is a sexually transmitted infection caused by a parasite, while a yeast infection is an overgrowth of fungus that already lives in your body. The confusion makes sense because they share some overlapping symptoms, particularly vaginal irritation and unusual discharge, but the similarities mostly end there.
What Causes Each One
Trichomoniasis is caused by a tiny single-celled parasite called Trichomonas vaginalis. It’s classified as the most common curable STI, and it spreads through sexual contact, typically from a penis to a vagina, vagina to penis, or vagina to vagina. You cannot get trichomoniasis from a toilet seat, swimming pool, or casual contact.
A yeast infection, on the other hand, is caused by Candida, a type of fungus that normally lives in the vagina in small amounts. Candida is a regular part of the vaginal microbiome. It only causes problems when something throws off the balance, like antibiotics, a weakened immune system, hormonal changes, or high blood sugar. A yeast infection is not sexually transmitted.
How the Symptoms Differ
Both conditions can cause itching, burning, and discomfort, which is a big reason people mix them up. But the discharge each one produces is quite different.
Yeast infections produce a thick, white discharge often described as looking like cottage cheese. It typically does not have a strong odor. Trichomoniasis produces a profuse, yellow-green, frothy discharge with a noticeable unpleasant smell. If your discharge is thin, discolored, bubbly-looking, or has a strong odor, that points away from yeast and toward something else entirely.
Trichomoniasis can also cause pain during urination and pain during sex. Many people with trich, though, have no symptoms at all, which makes it easy to carry and spread without knowing.
Why Self-Diagnosis Is Unreliable
One of the biggest risks with these two conditions is that people assume they have a yeast infection when they actually have something more serious. A study of women who purchased over-the-counter yeast infection treatments found that only 34% actually had a yeast infection. Nearly half of the women in the study delayed getting a correct diagnosis by treating themselves for the wrong condition.
That gap matters because trichomoniasis won’t go away on its own or respond to antifungal creams. If you treat what you think is a yeast infection and your symptoms don’t clear up, or if they come with colored discharge and odor, testing is the only way to know what’s going on.
How Each One Is Diagnosed
Your vaginal pH can be an early clue. A healthy vagina and one with a yeast infection both have a pH between 4.0 and 4.5. With trichomoniasis, the pH rises above 5.4. This is one reason a provider can often distinguish between the two during an office visit, though pH alone isn’t enough for a definitive answer.
For trichomoniasis, the initial test is usually a wet prep microscopy, where a sample of vaginal fluid is examined under a microscope to look for the parasite. This test is quick and inexpensive, but it isn’t always accurate, especially if parasite numbers are low. More reliable options include nucleic acid amplification tests, which detect the parasite’s genetic material, and culture tests, where the sample is grown in a lab over several days. Yeast infections are typically diagnosed by examining discharge under a microscope or with a culture if needed.
Because most people with trichomoniasis don’t have symptoms, routine STI screening is the only way many infections get caught.
The Stakes Are Different
A yeast infection is uncomfortable but generally harmless. It stays local, resolves with treatment, and doesn’t affect your long-term health. Trichomoniasis carries more serious risks if left untreated.
Untreated trichomoniasis is linked to a 1.5 times increased risk of acquiring HIV, because the inflammation it causes makes it easier for the virus to enter the body. In pregnant women, it’s associated with preterm delivery, low birth weight, and premature rupture of membranes. In rare cases, the parasite can be passed to a newborn during delivery, causing vaginal or respiratory infections. Trichomoniasis is also associated with pelvic inflammatory disease, which can affect fertility.
Treatment Looks Different Too
Yeast infections are treated with antifungal medications, many of which are available over the counter as creams or suppositories. Trichomoniasis requires a prescription antiparasitic medication taken by mouth. Antifungal creams will do nothing against the trich parasite.
Because trichomoniasis is sexually transmitted, your sexual partner needs to be treated at the same time, even if they have no symptoms. Without treating both partners, the infection will simply pass back and forth. With yeast infections, partner treatment is not necessary.
Trichomoniasis is fully curable with the right medication. Reinfection is common, though, so follow-up testing about three months after treatment is recommended to make sure the infection hasn’t returned.