How long does it take metronidazole to clear up trich?

Metronidazole is an antibiotic commonly prescribed to treat trichomoniasis, a common sexually transmitted infection caused by the parasite Trichomonas vaginalis. It usually takes around 7-14 days for metronidazole to fully clear up trichomoniasis symptoms and infection.

In this article, we will go over:

What is trichomoniasis?

Trichomoniasis, also known as “trich”, is a common sexually transmitted infection (STI) caused by a microscopic parasite called Trichomonas vaginalis. Trichomoniasis affects both women and men, but symptoms are more common in women.

In women, symptoms of trichomoniasis may include:

  • Green, yellow, or gray vaginal discharge with an unusual fishy odor
  • Genital itching or irritation
  • Pain or burning during urination or intercourse
  • Slight redness and swelling of the vulva or vagina

In men, trichomoniasis symptoms are usually mild or nonexistent. But some men may experience:

  • Discharge from the penis
  • Burning after urination or ejaculation
  • Burning or itching of the penis

Trichomoniasis is primarily spread through sexual contact with an infected partner. It can be transmitted through penis-to-vagina intercourse or vulva-to-vulva contact. Less commonly, it may be spread through contact with damp or moist objects like towels or wet clothing.

If left untreated, trichomoniasis can persist for months or even years. Although generally not considered a serious infection, trichomoniasis has been linked to adverse pregnancy outcomes and increased risk of HIV transmission. So timely treatment is recommended.

What is metronidazole and how does it work?

Metronidazole is an antibiotic specifically used to treat trichomoniasis, bacterial vaginosis, and certain parasitic infections. It goes by the brand names Flagyl, Metryl, or Protostat.

Metronidazole works by entering the trichomoniasis cells and damaging their DNA. This stops the cells from multiplying and allows the body’s immune system to clear the infection.

Metronidazole can be taken:

  • By mouth as a tablet or capsule
  • As a topical cream, gel, or lotion applied to the affected area
  • Given intravenously in a hospital setting for severe infections

For trichomoniasis, the usual adult prescription is 2 grams (2,000 mg) taken as a single dose by mouth. Lower doses may be prescribed for children. Topical metronidazole products are generally not recommended for treating trich itself, but may help alleviate symptoms.

How long after taking metronidazole do trichomoniasis symptoms improve?

Many patients report rapid relief of symptoms within 1-3 days after starting metronidazole treatment. Discharge, burning, and itching generally improve first, followed by resolution of redness and swelling.

However, every patient responds differently. Some people find their symptoms clear up within 12-24 hours, while for others it may take the full course of medication (usually 7 days) to see major improvement.

You should see your doctor if symptoms do not start to subside within 3-5 days after beginning treatment with metronidazole.

Factors that affect symptom improvement:

  • Severity of infection – The heavier the parasitic load, the longer it may take for symptoms to dissipate.
  • Overall health – Persons with weaker immune systems may be slower to respond to treatment.
  • Medication dose – Higher prescribed doses tend to act more quickly.
  • Medication route – Oral tablets work faster than topical creams/gels.
  • Medication absorption – Vaginal swelling can prevent proper absorption of topical meds.
  • Co-existing conditions – Certain chronic health issues may delay symptom relief.

When is trichomoniasis considered cleared/cured?

Trichomoniasis is considered fully cleared and cured when:

  • Symptoms have resolved completely and
  • Follow up testing confirms the parasite is no longer detected.

This usually occurs within 7-14 days after finishing the full metronidazole regimen. Even if symptoms dissipate sooner, it takes awhile for the antibiotics to fully eliminate all traces of the infection.

Your doctor may advise repeat testing around 4-6 weeks after treatment to confirm the trichomoniasis has been cured. This often involves:

  • Microscopic examination of vaginal/penile fluid samples
  • Cell culture testing
  • Nucleic acid amplification test (NAAT)

You should abstain from sexual activity until trichomoniasis has been cured in both you and your partner(s) to prevent reinfection.

Why metronidazole may not fully clear trichomoniasis:

  • Not taking the medication according to instructions
  • Prematurely stopping treatment before finishing the prescription
  • Re-exposure to an untreated infected partner
  • Immune deficiencies preventing eradication of infection
  • Antibiotic resistance to metronidazole

How to speed up clearing of trichomoniasis with metronidazole

You can help metronidazole work as quickly as possible to clear up trichomoniasis by:

Taking the full prescription

It’s crucial to complete the entire course of metronidazole, even if symptoms resolve sooner. This helps kill all the parasites and prevent recurrence.

Avoiding alcohol

Drinking alcohol while taking metronidazole can cause severe nausea, vomiting, cramps, flushing, and rapid heart rate. Avoid all alcohol for at least 48 hours after finishing metronidazole.

Treating partners

Make sure any sexual partners from the past 2 months also get treated to avoid passing the infection back and forth.

Practicing good genital hygiene

Wash the vulva/penis daily with mild soap and water. Change underwear frequently. Avoid douching, scented sprays, and heavily fragranced products.

Taking probiotics

Probiotics can help restore vaginal/urethral good bacteria disturbed by antibiotics. Ask your doctor for probiotic supplement recommendations.

Boosting immunity

Get extra rest, reduce stress, eat a balanced diet, and take daily vitamins to support your immune system’s ability to conquer the infection.

Using topical symptom relievers

Ask your doctor about using topical numbing creams, anti-itch medications, or cold compresses to relieve discomfort while the antibiotics work.

Increasing medication absorption

If using topical metronidazole, try inserting doses at night to allow better absorption. Also treat any co-existing yeast or bacterial vaginosis preventing proper adherence.

What happens if trichomoniasis is left untreated?

Without treatment, trichomoniasis can linger for years. Consequences may include:

  • Chronic, recurrent symptoms
  • Increased risk of HIV and other STIs
  • Spread to partners
  • Complications during pregnancy/childbirth
  • Infection ascending to the upper genital tract in women
  • Rarely, prostatitis in men

That’s why timely treatment with a full course of metronidazole or other antibiotics is important for a quick resolution of symptoms and preventing transmission and complications.

When to see a doctor

You should follow up with your doctor if:

  • Symptoms don’t start improving within 3-5 days of starting metronidazole
  • Symptoms return after treatment
  • Your partner tests positive for trichomoniasis
  • Repeat testing is still positive for trichomoniasis after treatment

This may indicate a need for further antibiotics, higher dosages, or treating any partners to prevent reinfection. Alert your doctor right away if you have:

  • Fever or chills
  • Lower abdominal or pelvic pain
  • Bleeding after intercourse

As these can signify complications requiring prompt medical evaluation.


In summary, it typically takes around 7-14 days for a course of oral or topical metronidazole to fully clear up trichomoniasis infection. Symptoms like discharge, odor, burning, and itching often start improving within 1-3 days, but complete parasite eradication takes longer.

To speed up clearing of trich with metronidazole: complete all doses, avoid alcohol, treat partners, practice good genital hygiene, take probiotics, support immunity, utilize symptom relievers, and improve medication absorption. See a doctor if symptoms persist or return after treatment. With appropriate antibiotics, trichomoniasis can usually be cured quickly with no long-term consequences.

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