Flagyl (metronidazole) is an antibiotic that also kills certain parasites. Doctors prescribe it to treat bacterial vaginosis, giardiasis, amoebiasis, and some mouth and abdominal infections. The key points to remember: avoid alcohol during treatment and for several days after it ends, complete the full course even if symptoms improve, a metallic taste is a common and temporary effect, and use during pregnancy requires the doctor's assessment.
What is Flagyl and why do doctors prescribe it?
Flagyl is the brand name for the active ingredient metronidazole, an antibiotic used to treat bacterial and parasitic infections [1]. It works by killing the bacteria and protozoa (single-celled parasites) that cause the infection [4]. You can find brief information about the active ingredient in the metronidazole entry in the medical glossary.
The medicine comes in several forms: tablets, syrup, suppositories, vaginal gel, and cream or gel for the skin. It may also be given by injection in a hospital [1]. It is available only by prescription [1]. In Jordan, the Jordan Food and Drug Administration (JFDA) regulates the registration and pricing of medicines. You can check the Flagyl page in the drug directory for the available form and strength.
Remember that antibiotics do not work against the common cold, influenza, or other viral infections. Taking them unnecessarily increases the risk of developing a drug-resistant infection later [4].
Which infections does Flagyl treat?
Your doctor chooses Flagyl based on the type of infection and the suspected bacterium or parasite. The following table summarizes its main uses:
| Condition | Important notes |
|---|---|
| Bacterial vaginosis | One of the known uses of the medicine [1]. It may be given as tablets or vaginal gel [5] |
| Trichomoniasis | A sexually transmitted parasitic infection. The partner is treated at the same time to prevent reinfection [5] |
| Gum infections and dental abscesses | Listed among the uses [1]. Another antibiotic may be combined with it at the dentist's discretion |
| Pelvic inflammatory disease and skin, wound, and ulcer infections | Listed among the uses [1] |
| Amoebiasis and giardiasis | Intestinal parasitic infections. Amoebiasis also has a liver form, according to the ClinicsJo drug directory |
| H. pylori infection and mild pseudomembranous colitis | Sometimes included in a treatment protocol set by the doctor (see the drug page) |
| Rosacea | The cream or gel is used, and it may take about two months or more before a clear difference appears [1][2] |
Flagyl does not treat every vaginal discharge
Vaginal infections can have similar symptoms, but their causes differ, and so do their treatments. Bacterial vaginosis and trichomoniasis respond to the appropriate antibiotics, whereas yeast infections (Candida) are usually treated with a cream or vaginal antifungal treatment [5]. Antibiotics themselves can also cause an overgrowth of yeast [5]. So do not treat yourself by guessing. Read about the difference between bacterial vaginosis and yeast infection or about vaginal yeast infection. Your doctor will usually take a medical history and examine you, and may examine a sample of the discharge under a microscope [5].
How is Flagyl used? Dosage, duration, and what to do if you miss a dose
The dose, form of the medicine, and length of treatment depend on the type and severity of the infection. Some infections are treated with a single dose, while others need a course that may last up to two weeks [2]. The usual dose for 500 mg tablets, as stated in the drug directory, is once, three times a day, though this may vary depending on the condition. Follow only what you have been told, and do not change the dose on your own.
- Tablets: Swallow whole with water, with food or immediately after it [2].
- Syrup: No food is needed. Shake well before measuring, and measure with the syringe or spoon provided, not a kitchen spoon [2].
- Vaginal gel: The usual dose for bacterial vaginosis is one applicator each night for 5 nights. Avoid intercourse while using it [2].
- Cream or gel: Apply a thin layer to the affected area, avoiding the eyes [2].
- Children: The dose depends on weight and requires a doctor's prescription or pharmacist's guidance. It should not be estimated at home.
Spread the doses evenly through the day. If the dose is three times daily, for example, take it in the morning, mid-afternoon, and at bedtime [2].
Complete the course even if you feel better
Continue treatment until the end, even if you feel better. Stopping early may allow the infection to return [2]. With many infections you will feel better within days, while with others it may take longer [1]. Treating both partners together is also essential for successful treatment of trichomoniasis [5].
Missed or extra doses
If you miss a dose, take it when you remember, unless the next dose is almost due. In that case, skip the missed dose and continue as usual. Never double the doses [2]. Taking one extra dose of tablets, syrup, or suppositories is unlikely to harm you. However, if you have taken more than one extra dose and new symptoms appear, seek advice from your doctor or pharmacist immediately [2]. For any severe symptoms, go to the nearest emergency department or call 911. Symptoms associated with an overdose include nausea, vomiting, loss of balance, and numbness [4].
Can I drink alcohol with Flagyl?
No. This is the most important rule of this treatment. Metronidazole can interact with alcohol and cause nausea or vomiting, stomach pain, redness and warmth of the face, difficulty breathing, and palpitations [3]. The ClinicsJo drug directory describes this as a reaction similar to that caused by disulfiram, which can progress to a drop in blood pressure.
How long should you wait after the last dose?
The UK National Health Service (NHS) recommends waiting two days after finishing treatment before drinking alcohol, so the medicine can leave the body [3]. The MedlinePlus leaflet for the injectable form states that alcohol should be avoided for at least 3 days after treatment ends [4], and the ClinicsJo drug directory also cites a period of 72 hours. Because sources differ slightly, it is safest to follow the three-day period, and to ask your pharmacist or doctor if your situation is special.
Hidden alcohol in everyday products
The concern is not limited to drinks. The same leaflet warns against products containing alcohol or propylene glycol [4]. Read the labels of cough medicines, oral solutions, and mouthwashes, and ask your pharmacist when in doubt. If you accidentally drink alcohol, stop drinking, monitor yourself, and see a doctor if troubling symptoms appear. Severe difficulty breathing or fainting requires calling 911 immediately.
What are Flagyl's side effects and how do I manage them?
Not everyone experiences side effects. The most common ones with tablets, syrup, suppositories, and vaginal gel are nausea or vomiting, diarrhea, and a mild metallic taste in the mouth [1]. The drug directory also adds dry mouth, headache, dizziness, and dark urine that is not harmful. The metallic taste and dark urine are well-known effects that do not, on their own, warrant concern. However, dark urine can also be a sign of dehydration (see the table).
| Symptom | What helps |
|---|---|
| Nausea or vomiting | Simple meals without rich or spicy food, taking the medicine after a meal or a light snack, and sipping water at short intervals. See a doctor if vomiting lasts more than 24 hours [3] |
| Diarrhea | Drink plenty of fluids, and do not take another anti-diarrheal medicine without consulting a pharmacist or doctor. See a doctor if it lasts more than 24 hours [3] |
| Metallic taste or coated tongue | Drink plenty of water and eat simple foods you like. If the tongue is heavily coated, it may be thrush (candidiasis), so ask a pharmacist or doctor [3] |
| Skin irritation with the cream or gel | Reduce how often you apply it, or stop for a few days until the irritation calms down. If it does not go away, stop using it and see a doctor [3] |
Signs of dehydration include passing little urine or having dark, strong-smelling urine [3]. If you use oral contraceptives and experience severe vomiting or diarrhea, or if it lasts more than 24 hours, their protection against pregnancy may be reduced. Check the pack leaflet [3] and speak with your doctor. For more information, read the comparison of contraception methods.
Numbness in the limbs
Long courses or high doses may cause numbness in the hands or feet (peripheral neuropathy). Tell your doctor as soon as it appears so they can decide whether the medicine should be stopped. The MedlinePlus leaflet confirms this, listing numbness, burning, and tingling among the symptoms that warrant contacting a doctor [4].
Pregnancy, breastfeeding, children, and other medicines
Pregnancy and breastfeeding
Flagyl should be avoided in the first trimester of pregnancy unless a doctor judges it necessary, according to the ClinicsJo drug directory. Tell your doctor if you are pregnant, planning a pregnancy, or breastfeeding, and contact them if you become pregnant during treatment [4]. On the other hand, bacterial vaginosis or trichomoniasis should not be left untreated during pregnancy, as they may increase the risk of preterm birth [5]. The decision is always made between the pregnant woman and her doctor. You can read more in the bacterial vaginosis guide.
Children
Doses for children are lower and depend on age and weight [2], and they should be determined by weight and given with a doctor's prescription or pharmacist's guidance. Do not give your child medicine that was left over from another family member. See can I use a prescription medicine prescribed for someone else?
Drug interactions
Tell your doctor and pharmacist about everything you take. According to the drug directory, the most significant interactions are:
- It enhances the effect of warfarin (a blood thinner), so INR monitoring is required.
- It raises lithium levels in the blood.
- Phenobarbital speeds up its breakdown, weakening its effect, and it should not be combined with busulfan.
- The MedlinePlus leaflet lists disulfiram (prohibited if taken within the last two weeks) and cimetidine as medicines the doctor must be informed about [4].
You should also inform your doctor about liver, kidney, or blood diseases, or Crohn's disease [4], as well as any previous drug allergy. To understand the difference between an interaction and a side effect, read what is a drug interaction?
A safety note: the injectable form's leaflet carries a warning that metronidazole caused cancer in laboratory animals, and advises discussing the benefits and risks with your doctor [4]. This is an additional reason to use it only when needed and for the duration set by your doctor.
When should you see a doctor, and when should you go to the emergency room?
Stop the medicine and contact your doctor immediately if you notice
Serious side effects are rare, occurring in fewer than 1 in 1,000 people [3], but they require stopping the medicine and contacting your doctor:
- Yellowing of the whites of the eyes or the skin (a sign of a liver or gallbladder problem).
- Unexpected infections, mouth ulcers, bruising, gum bleeding, or severe fatigue (may indicate a blood problem).
- Severe abdominal pain that radiates to the back (may be pancreatitis).
- Blurred or double vision [3].
- Numbness, burning, or tingling in the hands or feet [4].
Call 911 or go to the nearest emergency department immediately if you notice
- Headache with high fever and a stiff neck, especially with severe sensitivity to light (may rarely be meningitis).
- Hallucinations, mental confusion, or difficulty speaking (may indicate a very rare brain disorder) [3].
- Convulsions or fainting [4].
- Sudden swelling of the lips, mouth, throat, or tongue, difficulty breathing or swallowing, pale or bluish skin, or sudden dizziness and confusion (signs of a severe allergic reaction) [3].
Do not drive yourself to the emergency department. Ask someone else to take you or call an ambulance, and bring the medicine box and a list of your medicines [3]. To learn about drug allergies, read drug allergy.
How do I find the right doctor or clinic in Jordan?
Do not take Flagyl on your own before a doctor determines the cause of your symptoms. Choose a specialty based on your complaint:
- Vaginal discharge or itching: obstetrics and gynecology specialist.
- Persistent diarrhea or abdominal pain: internal medicine or gastroenterology.
- Gum pain or tooth abscess: dentist.
- Rosacea or skin infections: dermatologist.
You can search ClinicsJo by specialty and governorate, for example the directory of clinics that evaluate bacterial vaginosis in Jordan, or browse Amman listings such as Shmeisani clinics. Governorates have Ministry of Health primary health centers and mother and child health centers that can also serve as a starting point.
What to check in a doctor's profile
- Specialty and areas of clinical interest.
- Location, working hours, and the contact or booking methods available in the profile.
- The details the profile provides about the services offered.
Questions to ask your doctor or pharmacist
- What is the diagnosis, and do I need a test or culture before treatment?
- How long exactly is the course, and how should I take the doses?
- When can I drink alcohol again, and do my medicines or mouthwash contain alcohol?
- Does my partner need treatment as well?
- Does this medicine interact with my other medications, especially warfarin or lithium?
- What signs mean I should contact you or go to the emergency department?
Summary: key points to remember
Flagyl is effective against several bacterial and parasitic infections when prescribed for the correct diagnosis, but it is not suitable for every discharge or abdominal pain. Follow the dose and duration, complete the course, and avoid alcohol during treatment and for at least three days afterward. A metallic taste is unpleasant but usually temporary. Numbness, yellowing, severe rash, or changes in consciousness require immediate action. Consult your doctor about pregnancy and breastfeeding, and do not take a medicine prescribed for someone else.
Frequently asked questions
Can I drink alcohol while taking Flagyl?
No. Metronidazole interacts with alcohol, and you may experience nausea, vomiting, stomach pain, redness, palpitations, and difficulty breathing. Avoid alcohol throughout treatment and for at least three days (72 hours) after the last dose, watch for alcohol in some medicines and mouthwashes, and ask your pharmacist when in doubt.
Why do I have a metallic taste in my mouth with Flagyl?
A metallic taste is a common and temporary effect of metronidazole and does not mean there is a serious problem. It usually fades after treatment ends. Drinking plenty of water and eating simple foods you like can help. If your tongue is heavily coated, it may be thrush, so ask your pharmacist or doctor.
Can a pregnant woman use Flagyl?
Flagyl should be avoided in the first trimester of pregnancy unless the doctor considers it necessary. However, some untreated vaginal infections may increase the risk of preterm birth, so do not decide on your own. Tell your doctor if you are pregnant, breastfeeding, or planning a pregnancy, and they will choose the most suitable treatment for your situation.
Should I stop Flagyl when my symptoms improve?
No. Complete the course as prescribed by your doctor even if symptoms disappear, because stopping early may bring the infection back, especially parasitic and vaginal infections. For trichomoniasis, your partner must also be treated so the infection does not return. If you experience troubling side effects, contact your doctor before making any change.
Is dark urine with Flagyl dangerous?
Flagyl may cause dark-colored urine, which is a known effect and usually harmless. However, dark, strong-smelling urine with reduced urination may indicate dehydration, especially with vomiting or diarrhea, so drink more fluids. If yellowing of the eyes or skin appears, contact your doctor immediately.
When should I go to the emergency department after taking Flagyl?
Call 911 or go to the nearest emergency department if you experience swelling of the lips or throat, difficulty breathing, fainting, convulsions, hallucinations or confusion, or a severe headache with fever and a stiff neck. Stop the medicine, do not drive yourself, and take the medicine box with you.
Sources and references
- About metronidazole — NHS (UK National Health Service). Accessed: 2026-10-26.
- How and when to take or use metronidazole — NHS (UK National Health Service). Accessed: 2026-10-26.
- Side effects of metronidazole — NHS (UK National Health Service). Accessed: 2026-10-26.
- Metronidazole Injection: MedlinePlus Drug Information — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.
- Vaginitis | Vulvovaginitis — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.