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Flagyl (Metronidazole) Medication Overview
Flagyl, also known as metronidazole, is a prescription medication belonging to the class of nitroimidazole drugs. It is an antibiotic and antiprotozoal medication, meaning it fights against bacterial and protozoal infections. It has several indications and treats an array of conditions involving the bones, joints, skin, stomach, vagina, and more. While it carries some side effects and risks, Flagyl Metronidazole is generally well-tolerated and effective when clinically indicated.
Medical Indications for Flagyl (Metronidazole)
Flagyl can treat infections caused by certain bacteria and parasites. The details of these types of infections are detailed below.
Bacterial Infections
Flagyl (Metronidazole) is particularly effective against anaerobic bacteria, which survive in low-oxygen environments. This includes bacteria such as Clostridium difficile, Helicobacter pylori, and other anaerobic bacteria types. It works against these types of infections found in the skin, soft tissue, bone, joint, central nervous system (CNS), vagina, lower respiratory tract, and abdomen.
Protozoal Infections
Flagyl (Metronidazole) can also help to kill parasites, including Entamoeba histolytica, Trichomoniasis vaginalis, Balantidium coli, and blastocysts. These kinds of infections typically occur in the genitourinary system and digestive tract.
Other Conditions Flagyl (Metronidazole)Can Treat
In addition to the indications above, Flagyl can also treat rosacea and bacterial vaginosis.
Dosage and Administration for Flagyl (Metronidazole)
Flagyl comes in several routes of administration, including tablets, capsules, intravenous (IV), and vaginal formulations. The dose of Flagyl will depend on the condition, patient weight, patient age, patient health, and more. Typical dosing is as follows:
- Oral dosing. The usual dose for capsule Flagyl is 375 mg, while the tablet dosing is either 250 or 500 mg. The extended-release tablets should be taken on an empty stomach either one hour before or two hours after a meal. The other formulations can be taken with food to prevent stomach discomfort. Neither the tablets nor capsules should be split or crushed.
- IV dosing. The typical IV preparation is 5 mg/mL and the standard dose is 500 mg. Infusions should be given over the course of 30 to 60 minutes.
- Vaginal dose. The topical gel comes in 0.75% strength and contains 37.5 mg per applicator
Flagyl (Metronidazole) Dosage Based on Condition and Medical History
Your doctor will prescribe specific dosing based on your condition and medical history. Usual dosing for common conditions is listed below. These are normal doses; however, you should only ever take Flagyl as directed by your doctor.
- Bacterial vaginosis: 500 mg twice daily for seven days by mouth
- Trichomoniasis: 2 g or 500 mg twice daily for seven days by mouth
- Giardiasis: 250 mg three times daily or 500 mg twice daily for 5 to 7 days
- Abdominal infections: 500 mg every eight hours for four to seven days by mouth or IV
- Skin infections: 500 mg every six hours IV for 48 to 72 hours
- Surgical prophylaxis: 500 mg IV within one hour of surgery start
- Pelvic inflammatory disease (PID): 500 mg twice daily for 14 days
Potential Side Effects of Flagyl (Metronidazole)
Like with any drug, Flagyl (Metronidazole) can cause both minor and serious side effects. The more minor and temporary side effects and how to treat them are below:
- Nausea and vomiting. Avoid rich and spicy foods to help with stomach upset and maintain simple meals when eating. Depending on the type of Flagyl you are taking, you can take it with a meal or snack to avoid upset. Ensure to keep hydrated, especially if you are vomiting, and drink water frequently.
- Metallic taste. You may taste a metallic flavor in your mouth or feel like you have a furry tongue. Keep hydrated and eat simple foods. If you experience a furry tongue, this may indicate thrush. This would require follow-up with a healthcare provider.
- Diarrhea. If experiencing diarrhea, drink plenty of fluids to prevent dehydration. See medical attention if it lasts longer than 24 hours.
Potentially More Serious Side Effects of Flagyl (Metronidazole)
Like with any drug, Flagyl (Metronidazole) can cause both minor and serious side effects. The more minor and temporary side effects and how to treat them are below:
- Allergic reactions
- Seizures
- Changes to heart rhythm
- Dizziness
- Confusion
- Eye pain or changes to vision
- Liver injury
- Mouth blisters
- Fever
- Abnormal vaginal discharge, odor, or itching
- Neck pain or stiffness
- Light sensitivity
- Numbness or pain in the feet or hands
If you experience any of the above side effects, make sure to tell your doctor right away. These could be a sign of a more serious medical condition that requires attention.
Precautions and Contraindications for Flagyl (Metronidazole)
There are several precautions to take when starting Flagyl (Metronidazole). People with certain conditions may require more frequent monitoring or certain laboratory tests with therapy.
- Liver impairment. Individuals that have liver problems will take longer to metabolize Flagyl. Depending on the level of severity, your doctor may lower your dose and monitor for adverse events.
- Kidney impairment. Individuals with end stage renal disease (ESRD) may take longer to excrete Flagyl. In these individuals, frequent monitoring for adverse events is recommended.
- Drug-resistance. Flagyl should only be prescribed and taken if there is a high likelihood that it will work against the suspected infection. Inappropriate antibiotic or antiparasitic therapy increases your chances of developing drug-resistant parasites and bacteria.
- Blood dyscrasias. In patients with a history of blood dyscrasias, additional monitoring of leukocyte counts should be conducted before and after treatment. Flagyl runs the risk of inducing a mild leukopenia (low white blood cell count).
- Fungal superinfections. Individuals with existing candidiasis infection may have more severe symptoms, which would require additional medical intervention.
Who Should Not Take Flagyl (Metronidazole)
Additionally, certain individuals should not take Flagyl (Metronidazole). Specifically, individuals with:
- Serious allergy to metronidazole or other nitroimidazole derivatives
- Cockayne syndrome, which can cause severe liver issues or liver failure
- First-trimester pregnancy
Interactions with Flagyl (Metronidazole)
Flagyl is known to interact with certain medications and substances, including:
- Alcohol. Patients should not drink alcohol during treatment and for at least three days after treatment. If alcohol is consumed, there is a risk of nausea, vomiting, stomach cramps, flushing, and headaches.
- Disulfiram. Patients who have taken disulfiram within the preceding two weeks of treatment should not take metronidazole.
- Blood thinners. Flagyl can increase prothrombin time, thus affecting how blood thinners work. If taking together, your INR should be monitored more carefully.
- Lithium. Lithium toxicity has occurred in individuals taking high doses of lithium with Flagyl.
- CYP450 inducers and inhibitors. Certain drugs affect how certain liver enzymes work, which affects how slow or fast the body metabolizes Flagyl.
- Busulfan. Flagyl can increase busulfan levels in the body, resulting in busulfan toxicity.
Effectiveness and Expectations of Flagyl (Metronidazole)
Flagyl is usually very effective in treating bacterial and protozoal infections when directed. Individuals should always finish their full course of Flagyl (Metronidazole), even when their symptoms improve, to ensure the infection is fully gone. Make sure always to take your dosage as prescribed for the full course for optimal effectiveness.
Long-Term Use and Monitoring of Flagyl (Metronidazole)
Long-term treatment with Flagyl (Metronidazole) is not recommended because of the risk of drug-resistant bacteria and associated side effects.
Alternatives and Complementary Therapies
Usually, there are other antibiotics that will work against a particular infection other than just Flagyl (Metronidazole). You may also utilize probiotics and dietary changes after treatment to restore the “good” bacteria killed by Flagyl and improve gut health.
Frequently Asked Questions About Flagyl (Metronidazole)
How does Flagyl work?
Flagyl works by interacting with the DNA (genetic material) in the bacteria or parasite. It causes DNA breakage and breakdown, resulting in cell death in susceptible organisms.
Can you drink while on Flagyl (Metronidazole)?
You should not drink when you take Flagyl. Additionally, you should continue to avoid drinking for at least three days after finishing Flagyl therapy.
How long does it take Flagyl to work?
It may take a few days to start seeing a resolution of your symptoms after starting Flagyl (Metronidazole).
Do I have to finish Flagyl even if I feel better?
You should always finish the full course of antibiotics you are prescribed, even if you feel better. Even if your symptoms have subsided, you may still have bacteria in your body. If you stop too early, you can develop what is known as “antibiotic resistance”. This occurs when the bacteria in your body changes so that it is resistant to the medication. That medication will no longer work for that bacteria and may not work again in the future. Thus, finishing your whole course of Flagyl (Metronidazole) is very important.
Can Flagyl (Metronidazole) work for the cold and flu?
Flagyl kills certain bacteria and parasites, meaning that it does not fight against viral infections. The common cold and flu are considered viral infections and thus cannot be treated with Flagyl (Metronidazole).
How do I store the Flagyl (Metronidazole)?
Store your Flagyl medication at room temperature. Protect it from light and keep it out of reach of pets and children.
Do I need to take Flagyl with food?
You can take Flagyl (Metronidazole) with food. However, if you are taking the extended-release version of Flagyl, you must space it out either one hour before a meal or two hours after a meal.
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