Metronidazole 500 mg twice a day for 7 days is a specific prescription regimen used for certain bacterial and parasitic infections. For women, this exact dosing schedule is recommended for bacterial vaginosis (BV) and trichomoniasis.
The dose and duration matter. Metronidazole 500 mg twice a day for 7 days is not a general treatment for vaginal discharge, urinary symptoms, or pelvic pain. It does not treat every infection that can cause similar symptoms.
If you have been prescribed metronidazole 500 mg twice a day for 7 days, you will generally take one 500 mg tablet every 12 hours for seven days, for a total of 14 tablets. Always follow the instructions on your prescription because your clinician may give you different directions based on your diagnosis.
Here is what metronidazole 500 mg twice a day for 7 days actually treats, what it does not treat, how to take it, common side effects, and what to do if your symptoms do not improve.
TL;DR: Key Takeaways
- What metronidazole 500 mg twice a day for 7 days treats: This is a recommended regimen for symptomatic bacterial vaginosis and for trichomoniasis in women.
- What it does not treat: It is not a standard treatment for yeast infections or typical urinary tract infections, and it is not adequate by itself for pelvic inflammatory disease.
- How to take it: Take one 500 mg tablet twice daily for seven days, following your prescription instructions.
- How many tablets: A typical seven-day course means 14 tablets total.
- Common side effects: Nausea, diarrhea, headache, metallic taste, and sometimes dark urine.
- Do not stop early: Feeling better does not necessarily mean the infection has been completely treated. Follow the prescribed seven-day course unless your clinician tells you otherwise.
- For trichomoniasis: Sex partners should be treated, and sexually active women should be retested about three months after treatment because reinfection is common.
Have BV or trichomoniasis symptoms and want a clinician to review them from home? Book a $39 online urgent care visit with August AI. A US-licensed clinician can review your symptoms and medical history and prescribe treatment when clinically appropriate. The visit does not guarantee a prescription, and medication costs are separate. If you have severe pelvic pain, high fever, pregnancy-related concerns, or symptoms that may require an examination or testing, in-person care may be more appropriate.
What is metronidazole 500 mg twice a day for 7 days used for?
Metronidazole 500 mg twice a day for 7 days has two important uses in women: bacterial vaginosis and trichomoniasis.
Metronidazole belongs to a class of medicines called nitroimidazoles. It works against certain anaerobic bacteria and the parasite Trichomonas vaginalis. It does not work against every type of bacteria, and it does not treat fungal infections such as Candida.
That distinction matters because vaginal discharge, odor, itching, burning, and painful urination can have several different causes. Having one or more of these symptoms does not automatically mean metronidazole is the right medication.
The exact diagnosis determines whether metronidazole 500 mg twice a day for 7 days is appropriate.
People also ask
No. If you missed a dose of metronidazole, take it as soon as you remember, unless your next scheduled dose is only an hour or two away. In that case, skip the missed one and return to your normal 12-hour rhythm. Never take two tablets together to catch up, because doubling the dose increases nausea and metallic taste without improving the cure.
Yes. It is one of CDC's acceptable oral regimens for symptomatic bacterial vaginosis in pregnancy , alongside 250 mg three times daily for 7 days; tinidazole is avoided in pregnancy. For trichomoniasis, CDC notes that studies of single-dose and multidose metronidazole have shown no evidence of teratogenicity , and symptomatic pregnant women should be tested and treated at any stage.
Metronidazole 500 mg twice a day for 7 days for bacterial vaginosis
Bacterial vaginosis, or BV, happens when the normal balance of bacteria in the vagina changes. Anaerobic bacteria become more abundant while protective lactobacilli decrease.
Common BV symptoms include thin vaginal discharge and a strong fishy odor, particularly after sex. Some people have no symptoms.
The CDC lists metronidazole 500 mg orally twice daily for seven days as a recommended regimen for symptomatic BV. Other recommended options include metronidazole 0.75% vaginal gel for five days or clindamycin 2% cream for seven days.
If your clinician prescribed metronidazole 500 mg twice a day for 7 days for BV, take it according to the prescription rather than changing the dose or stopping once symptoms improve.
The seven-day schedule is the recommended oral regimen for this indication. Do not shorten the course simply because the odor or discharge improves after a few days.
For more detail, see our guide to metronidazole for BV: how the 7-day course differs from trichomoniasis treatment.
If you are unsure whether your symptoms are BV or yeast, see BV vs yeast infection: symptoms, smell & treatment differences.
People also ask
Sometimes. For trichomoniasis, yes: sexual partners need treatment or you will simply be reinfected, and male partners are typically given a single 2 g oral dose rather than the 7-day course. For bacterial vaginosis, routine treatment of male partners is not part of standard care, so a partner who was not offered anything has not been overlooked.
No. Its activity covers anaerobic bacteria and protozoa, and typical urinary tract infections are caused by organisms outside that spectrum, most often E. coli. Burning with urination can occur with vaginal infections too, which is why the symptoms get confused. If urinary symptoms are the main problem, that needs its own assessment and a different antibiotic.
Metronidazole 500 mg twice a day for 7 days for trichomoniasis
Trichomoniasis is a sexually transmitted infection caused by the parasite Trichomonas vaginalis.
Women may experience vaginal itching or irritation, burning, painful urination, or unusual discharge that can be yellowish or greenish. However, many people with trichomoniasis have no symptoms.
For women with trichomoniasis, the CDC recommends metronidazole 500 mg orally twice daily for seven days. This replaced the older approach of routinely using a single 2 g dose in women.
In the clinical trial supporting the recommendation, the seven-day regimen reduced the proportion of women who tested positive again at one month by about half compared with the 2 g single dose.
The recommended regimen is different for men with trichomoniasis. The CDC recommends metronidazole 2 g orally as a single dose for men, with other regimens used in specific situations.
Because trichomoniasis is an STI, current sex partners should be treated to reduce the risk of reinfection. Sex should be avoided until treatment has been completed and symptoms have resolved.
People also ask
Yes. Oral tablets are absorbed through the gut, so menstrual bleeding has no effect on how the medicine works, and there is no reason to pause or restart the course. That is one practical advantage over intravaginal gel, where timing around bleeding is a common source of confusion and missed applications.
BV vs. trichomoniasis: same metronidazole dose, different infection
| Feature | Bacterial vaginosis | Trichomoniasis |
|---|---|---|
| Cause | Change in vaginal bacterial balance | Trichomonas vaginalis, a parasite |
| STI? | No | Yes |
| Recommended regimen for women | Metronidazole 500 mg twice daily for 7 days | Metronidazole 500 mg twice daily for 7 days |
| Partner treatment | Not routinely recommended | Important to prevent reinfection |
| Retesting | No routine test of cure for uncomplicated BV | Retesting recommended for sexually active women about 3 months after treatment |
The fact that metronidazole 500 mg twice a day for 7 days is used for both conditions can make them seem interchangeable. They are not.
BV is a change in the vaginal bacterial balance, while trichomoniasis is an STI caused by a parasite. Partner treatment and follow-up are therefore different.
What does metronidazole 500 mg twice a day for 7 days not treat?
Knowing what this regimen does not treat is just as important as knowing what it does treat.
Yeast infections
Vaginal yeast infections are caused by Candida, a fungus. Metronidazole does not treat Candida.
Typical symptoms can include intense itching, irritation, redness, and thick white discharge. A yeast infection generally requires antifungal treatment, such as fluconazole or a topical azole, depending on the diagnosis and individual circumstances.
If you have symptoms that could be either BV or a yeast infection, do not assume metronidazole 500 mg twice a day for 7 days will treat both.
Typical urinary tract infections
Most uncomplicated UTIs are caused by bacteria such as Escherichia coli. Metronidazole is not a standard treatment for uncomplicated UTIs.
If you have burning with urination, frequent urination, urgency, or lower abdominal discomfort, you may need a urine evaluation and a different antibiotic if a UTI is confirmed.
Taking metronidazole for a typical UTI will not provide the appropriate treatment.
Pelvic inflammatory disease
Pelvic inflammatory disease, or PID, requires broader antibiotic coverage than metronidazole alone provides.
Metronidazole can be included as part of certain PID treatment regimens, but metronidazole 500 mg twice a day for 7 days by itself is not adequate treatment for PID.
Severe pelvic or abdominal pain, fever, chills, vomiting, or feeling seriously unwell warrants prompt medical evaluation.
Other STIs
Metronidazole is not the standard treatment for chlamydia, gonorrhea, or syphilis. Those infections require different testing and treatment approaches.
If you are unsure whether your symptoms could be an STI, our guide to STD testing online explains what testing can involve and when treatment may be needed.
How to take metronidazole 500 mg twice a day for 7 days
The usual meaning of metronidazole 500 mg twice a day for 7 days is one 500 mg tablet approximately every 12 hours for seven days.
That means:
- 500 mg per dose
- 2 doses per day
- 7 days of treatment
- 14 tablets total, if each tablet contains 500 mg
For example, your clinician may instruct you to take one dose in the morning and one in the evening. Try to take the doses at roughly the same times each day.
Follow the instructions on your prescription label. Do not change the dose, take extra tablets, or extend the course without speaking with your clinician.
You can take metronidazole with food if it causes stomach upset. Follow any specific instructions from your clinician or pharmacist regarding your formulation.
Do not use leftover metronidazole from a previous infection. Even if the symptoms seem identical, the underlying cause may be different.
How long does metronidazole 500 mg twice a day take to work?
Symptoms may begin improving within the first few days of treatment, but the timing varies depending on the infection and the individual.
If you are taking metronidazole 500 mg twice a day for 7 days, do not stop the medication simply because you feel better after two or three days.
Improved symptoms are not the same thing as completing the prescribed treatment. Continue taking the medication according to your prescription unless your clinician tells you to stop.
If symptoms are not improving, become worse, or return after treatment, contact a clinician rather than automatically starting another course.
What are the side effects of metronidazole 500 mg twice a day?
Common side effects of oral metronidazole can include:
- Nausea or stomach upset
- Diarrhea
- Headache
- Metallic or unpleasant taste
- Mild dizziness
- Darkened urine
These side effects are generally temporary.
Taking the medication with food may help with stomach upset when permitted by your prescription instructions.
Contact your clinician if side effects are severe, persistent, or difficult to distinguish from symptoms of the infection itself.
What if you miss a dose?
If you miss a dose of metronidazole 500 mg twice a day for 7 days, take it when you remember unless it is nearly time for your next scheduled dose.
If it is almost time for the next dose, skip the missed dose and return to your normal schedule.
Do not take two 500 mg tablets at once to make up for a missed dose unless a clinician specifically instructs you to do so.
If you vomit soon after taking a dose, contact your pharmacist or clinician. Whether another dose is needed depends on how soon you vomited and how much medication may have been absorbed.
Can you drink alcohol while taking metronidazole?
The traditional warning says to avoid alcohol during metronidazole treatment and for several days afterward. The CDC's STI guidance notes that available evidence does not provide convincing support for a disulfiram-like reaction between metronidazole and alcohol.
That does not mean alcohol is necessarily a good idea while you are taking the medication. Metronidazole itself can cause nausea, stomach upset, headache, and an unpleasant taste, and alcohol may make those symptoms worse.
If you want the simplest practical approach, avoid alcohol while taking metronidazole 500 mg twice a day for 7 days.
If you already had a drink after taking metronidazole and are concerned, contact your pharmacist or clinician for individualized advice.
For a deeper explanation, see our guide on metronidazole and alcohol: is the warning a myth or a real risk?.
What if metronidazole 500 mg twice a day for 7 days does not work?
Do not automatically repeat the same seven-day course if your symptoms persist or return.
Persistent symptoms can have several explanations. The original diagnosis may have been incorrect, the infection may have returned, reinfection may have occurred, or another condition may be causing the symptoms.
This is particularly important with trichomoniasis. Reinfection is common, which is why current sex partners should be treated and sexually active women should be retested approximately three months after treatment.
If symptoms continue after metronidazole 500 mg twice a day for 7 days, your clinician may recommend additional testing or a different treatment approach.
For more information about when online care can be appropriate for antibiotic prescribing, see can a telehealth doctor prescribe antibiotics?.
When should you get medical care?
Seek urgent medical care if you develop:
- Difficulty breathing, facial or throat swelling, widespread hives, or another sign of a severe allergic reaction
- Severe or worsening pelvic or abdominal pain
- High fever or chills with pelvic symptoms
- Seizures or severe neurological symptoms
Contact a clinician if:
- Your symptoms are not improving after several days of treatment
- Your symptoms return after completing the seven-day course
- You develop persistent numbness, tingling, or significant dizziness
- You suspect you have another infection in addition to BV or trichomoniasis
- You may have been exposed to an STI
If you are pregnant, breastfeeding, taking other medications, or have previously had an allergic reaction to metronidazole or another nitroimidazole, tell your clinician before starting treatment.
Metronidazole can be used during pregnancy when clinically indicated, so pregnancy alone does not mean this medication should automatically be avoided.
Conclusion
Metronidazole 500 mg twice a day for 7 days is a specific treatment regimen, not a general-purpose antibiotic. For women, it is a recommended regimen for symptomatic bacterial vaginosis and for trichomoniasis.
The same dose can be used for two different infections, but the rest of the treatment plan is not the same. Trichomoniasis requires attention to sex-partner treatment and follow-up testing, while uncomplicated BV does not routinely require partner treatment.
Metronidazole 500 mg twice a day for 7 days does not treat yeast infections or typical UTIs, and it cannot be used by itself as a complete treatment for PID. If you are not sure what is causing your symptoms, getting the diagnosis right is more important than simply taking an antibiotic.
If this regimen was prescribed for you, take it exactly as directed and complete the seven-day course unless your clinician tells you otherwise. If symptoms persist, return, or become severe, get reevaluated instead of starting another course on your own.
Frequently Asked Questions
No. Metronidazole 500 mg twice a day for 7 days is not a standard treatment for the bacteria that cause most uncomplicated UTIs.
If you have burning with urination, urgency, frequent urination, or lower abdominal discomfort, you should be evaluated for a UTI rather than taking leftover metronidazole.
Do not stop the course early unless your clinician tells you to.
Symptoms can improve before treatment is complete. If you were prescribed metronidazole 500 mg twice a day for 7 days, take it for the full seven days as directed.
No. Yeast infections are caused by fungi, while metronidazole treats certain bacteria and parasites.
A confirmed yeast infection generally requires antifungal treatment instead.
Yes. Flagyl is a brand name for metronidazole. Generic metronidazole contains the same active ingredient.
The important details are the medication strength and dosing instructions on your prescription.
In appropriate cases, yes. A telehealth clinician can review your symptoms, medical history, medications, and other relevant information to determine whether metronidazole is appropriate.
Online care may be useful when symptoms clearly fit a condition that can be evaluated remotely. However, persistent, recurrent, severe, or unclear symptoms may require an in-person examination or laboratory testing.
A telehealth visit does not guarantee a prescription.
Routine treatment of male sex partners is not recommended for uncomplicated BV.
Trichomoniasis is different. Current sex partners should receive treatment for trichomoniasis to reduce the risk of reinfection.
Sexually active women should be retested approximately three months after treatment because repeat infection is common.
If testing is being done to investigate persistent or recurrent infection, timing and test type matter. For example, the CDC advises against using a NAAT before three weeks after treatment completion because residual nucleic acid can produce a misleading positive result.
