Trichomoniasis: Symptoms, Treatment, and Testing in Singapore
Trichomoniasis (often shortened to "trich") is one of the most common curable STIs worldwide, caused by the protozoan parasite Trichomonas vaginalis. Around 70% of people with trichomoniasis have no symptoms, and men in particular are usually asymptomatic carriers, so routine testing is important.
Medically reviewed by Dr. Qiao Yufei, MD
This guide covers how trichomoniasis spreads, symptoms in men and women, single-dose metronidazole treatment, and why both partners must be treated at the same time. Trichomoniasis is one of several conditions covered in our broader STDs in Singapore overview.
What is trichomoniasis?
Trichomoniasis is a sexually transmitted infection caused by Trichomonas vaginalis, a microscopic single-celled protozoan parasite. Unlike chlamydia or gonorrhoea, which are bacterial, or herpes, which is viral, trichomoniasis is parasitic. This is clinically important because standard antibiotics do not work: trichomoniasis is treated with antiprotozoal medication (metronidazole or tinidazole).
According to the US Centers for Disease Control and Prevention (CDC), trichomoniasis is the most common curable non-viral STI worldwide, with an estimated 156 million new cases globally each year.
Yes. A single oral dose of metronidazole (2 g) or tinidazole (2 g) typically cures trichomoniasis. Both partners must be treated at the same time to prevent ping-pong reinfection. Avoid alcohol during and for 24 to 72 hours after metronidazole because the combination can cause severe nausea, vomiting, and headache.
How trichomoniasis spreads
Trichomoniasis is transmitted through sexual contact with an infected person. The parasite cannot survive long outside the body, so non-sexual transmission is essentially zero.
- Unprotected vaginal intercourse (the most common route)
- Vulva-to-vulva contact between female partners
- Shared sex toys without a fresh condom or thorough cleaning between partners
Trichomoniasis is uncommon at other sites
Unlike chlamydia and gonorrhoea, trichomoniasis does not commonly infect the mouth, throat, or rectum. Anal trichomoniasis is rare. The parasite preferentially colonises the lower genital tract: vagina and urethra in women, urethra in men.
You cannot get trichomoniasis from
- Toilet seats, swimming pools, or hot tubs (the parasite dies quickly outside the body)
- Casual contact such as hugging or shared utensils
Who is at higher risk?
- People with multiple sexual partners or inconsistent condom use
- Trichomoniasis affects older adults more than other curable STIs (median age 40+)
- People with a previous STI diagnosis
Signs and symptoms of trichomoniasis
Trichomoniasis is often silent. Around 70% of people with trichomoniasis have no symptoms, and men in particular are usually asymptomatic carriers. When symptoms appear, they typically develop 5 to 28 days after exposure.
In women
- Frothy yellow-green vaginal discharge with a strong fishy odour
- Vulval itching, soreness, or burning
- Pain or discomfort during intercourse
- Pain or burning during urination
- Lower abdominal discomfort (less common)
- "Strawberry cervix" appearance on examination (small red spots)
In men
- Most men have no symptoms at all
- When present: discharge from the penis (clear or slightly cloudy)
- Mild burning during urination or after ejaculation
- Mild itching or irritation inside the penis
The male urethra is a transient host for Trichomonas vaginalis: the parasite often clears on its own within weeks in men, sometimes without ever causing symptoms. However, men can still pass the parasite to partners during this period, which is why partner notification and concurrent treatment matter.
How trichomoniasis is diagnosed
Diagnosis is straightforward at Mediway Medical Centre:
- NAAT (nucleic acid amplification testing): the most accurate test, performed on a vaginal swab in women or first-catch urine in men
- Wet-mount microscopy: a vaginal fluid sample examined under a microscope, which can detect the motile parasite directly (less sensitive than NAAT)
- Vaginal pH and odour test: pH > 4.5 and a positive "whiff test" (fishy odour with potassium hydroxide) suggest trichomoniasis or bacterial vaginosis
Most NAAT results return within a few working days. Treatment can usually start at the same visit if clinical suspicion is high.
Trichomoniasis treatment
Trichomoniasis is treated with antiprotozoal medication, not standard antibiotics. The two effective drugs are:
- Metronidazole: a single oral dose of 2 g (current first-line); alternative is 500 mg twice daily for 7 days
- Tinidazole: a single oral dose of 2 g (slightly fewer gastrointestinal side effects)
Treat both partners
Concurrent partner treatment is essential, even if the partner has no symptoms. If only one partner is treated, the parasite passes back during the next sexual encounter ("ping-pong reinfection"). Avoid sex for at least 7 days after both partners complete treatment.
Avoid alcohol
Both metronidazole and tinidazole interact with alcohol, causing a disulfiram-like reaction (severe nausea, vomiting, headache, flushing). Avoid alcohol during treatment and for at least 24 hours after metronidazole, or 72 hours after tinidazole.
Pregnancy
Metronidazole is considered safe in pregnancy when treatment is medically indicated. Untreated trichomoniasis in pregnancy can cause preterm birth and low birth weight, so treatment is usually recommended.
Test of cure
Repeat testing 3 months after treatment is recommended for women, since reinfection is common.
How to prevent trichomoniasis
Practise safe sex
- Use condoms consistently and correctly during vaginal intercourse
- Use a fresh condom or barrier on shared sex toys between partners
- Limit the number of sexual partners
Get screened regularly
Routine STI screening detects asymptomatic trichomoniasis, particularly important if you are over 40, in a new relationship, or have new or multiple partners. Test of cure 3 months after treatment is recommended for women because reinfection is common.
Communicate with your partner
If you test positive, your current partner (and any partner from the past 60 days) should be tested and treated at the same time, even if they have no symptoms. Resume sex only after both partners have completed treatment and are symptom-free.
What happens if trichomoniasis is left untreated?
Untreated trichomoniasis can cause prolonged inflammation and increase certain risks:
- Persistent vaginal or urethral inflammation with chronic discharge, itching, and discomfort
- Increased HIV transmission risk: trichomoniasis can make it easier to acquire or pass on HIV
- Pregnancy complications: preterm birth, low birth weight, and premature rupture of membranes
- Pelvic inflammatory disease (rare but possible if the infection ascends)
- Recurrent reinfection if a partner is not also treated (the "ping-pong" effect)
All of these complications are preventable with a single dose of metronidazole or tinidazole, which is why timely testing and treatment matter.
Frequently asked questions
01 What is trichomoniasis?
Trichomoniasis is a sexually transmitted infection caused by a microscopic parasite called Trichomonas vaginalis (not a bacterium or virus). It is one of the most common curable STIs worldwide. Many people with trichomoniasis have no symptoms, especially men, which is why partner notification and screening are important. Trichomoniasis is curable with prescription treatment.
02 What are the symptoms of trichomoniasis?
Many people with trichomoniasis have no symptoms. When symptoms occur in women, they may include frothy yellow-green vaginal discharge, vaginal itching or irritation, painful urination, pain during intercourse, or lower abdominal pain. Symptoms can be confused with bacterial vaginosis (BV) or yeast infection because of overlapping signs, but trichomoniasis is a different parasitic infection that needs specific treatment, so testing confirms the diagnosis. In men, symptoms (when present) may include thin penile discharge, burning during urination, or itching inside the penis.
03 How long after exposure do trichomoniasis symptoms appear?
Symptoms, when they occur, typically appear within 5 to 28 days after exposure, though some people remain asymptomatic for longer or never develop noticeable symptoms. Because of this variable timing and the frequent absence of symptoms (especially in men), regular STI testing is recommended after potential exposure or with a new sexual partner.
04 How do you get trichomoniasis?
Trichomoniasis is usually transmitted through sexual contact with an infected partner, especially vaginal sex. It can affect the vagina, vulva, urethra, or penis. It is not spread through casual contact such as hugging, sharing utensils, or using the same toilet. Sex toys may also transmit infection if shared without cleaning or a fresh condom.
05 Is trichomoniasis curable?
Yes. Trichomoniasis is curable with appropriate treatment prescribed by a doctor. Untreated trichomoniasis may persist without treatment. Having had trichomoniasis does not protect you from getting it again. Reinfection is possible if a sexual partner is not treated. Sexual partners should be tested and treated at the same time to prevent the infection bouncing back.
06 How is trichomoniasis treated?
Trichomoniasis is treated with prescription medication. Your doctor will choose the appropriate treatment and dosing based on your situation, allergies, pregnancy status, and current clinical guidance. Complete the prescribed course and avoid sexual activity until both you and your partner have completed treatment. Avoid alcohol during and shortly after treatment with certain medications, as advised by your doctor.
07 What are the complications of untreated trichomoniasis?
Untreated trichomoniasis may cause complications. In women, it has been associated with pregnancy complications such as preterm delivery and low-birthweight babies, and may increase the risk of acquiring or transmitting other STIs, including HIV. In men, it may rarely cause inflammation of the prostate or epididymis. Trichomoniasis has also been associated with inflammation of the reproductive tract.
08 How can I prevent trichomoniasis?
Trichomoniasis risk can be reduced by using condoms consistently during vaginal, anal, or oral sex, having regular STI screenings (especially with new or multiple partners), maintaining a mutually monogamous relationship with a tested uninfected partner, and ensuring sex toys are cleaned or covered with a fresh condom between partners. Open conversations with partners about STI status also support prevention.
09 Why must my partner also be treated?
Trichomoniasis can pass back and forth between sexual partners, creating a reinfection cycle. If one partner is treated and the other is not, reinfection is very likely once sexual activity resumes. To prevent this, all current sexual partners should be tested and treated at the same time, and sexual activity should be avoided until everyone has completed treatment as advised.
10 Where can I get tested for trichomoniasis in Singapore?
You can get tested at Mediway through our STD testing service. Trichomoniasis is typically diagnosed via swab from the affected area (vagina or urethra) or urine sample, depending on symptoms and possible exposure. The doctor will recommend the appropriate test and discuss treatment if needed. Learn more on our STD testing in Singapore page, or speak to our team to arrange a confidential consultation.
Related conditions and next steps
References: CDC: Trichomoniasis fact sheet · WHO: STIs fact sheet · HealthHub Singapore
This page is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Consult a qualified healthcare professional for diagnosis and treatment of suspected trichomoniasis.