Metronidazole: A Powerful Antibiotic for a Range of Infections
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Order Metronidazole →What Is Metronidazole?
Metronidazole is a potent antibiotic used to treat a variety of bacterial and parasitic infections. It is available only with a prescription, which can be obtained following a consultation with a qualified healthcare professional — including via Access Doctor’s GPhC-regulated online consultation service. Metronidazole is available in tablet form, as a topical gel (Zidoval), and as a cream — making it a versatile tool in treating a broad range of infections.
What Does Metronidazole Treat?
Metronidazole is a nitroimidazole antibiotic that targets anaerobic bacteria and protozoa — organisms that thrive in environments with little to no oxygen. This mechanism makes it effective against a wide spectrum of infections:
Bacterial Vaginosis & PID
The most common use — first-line NICE-recommended treatment for BV and pelvic inflammatory disease.
Dental Infections
Dental abscesses and infected gums frequently respond well to metronidazole treatment.
Skin Conditions
Rosacea (as gel or cream), infected skin ulcers, bedsores, and wound infections.
Internal Infections
Trichomoniasis (STI), giardiasis, amoebiasis, C. difficile infection, diverticulitis, and intra-abdominal infections.
Important: Metronidazole is ineffective against viral infections such as colds, flu, or COVID-19. It should only be used for infections confirmed or strongly suspected to be bacterial or parasitic by a qualified healthcare professional.
How Does Metronidazole Work?
Once inside a bacterial or parasitic cell, metronidazole is chemically reduced by anaerobic organisms — creating unstable, reactive intermediate compounds. These compounds damage the organism’s DNA, disrupting essential cellular functions and causing cell death.
This mechanism makes metronidazole particularly effective against anaerobic pathogens and certain protozoa, distinguishing it from many other antibiotics that require oxygen-dependent metabolic processes. It acts as both an antibacterial and an antiparasitic agent — hence its wide range of clinical applications.
Key Facts About Metronidazole
- Avoid alcohol during treatment and for at least 48 hours after. Combining metronidazole with alcohol triggers a disulfiram-like reaction — see our full guide: Metronidazole side effects and interactions.
- Common side effects include nausea, a metallic taste, diarrhoea, and occasionally headache or dizziness.
- Treatment duration varies by condition — from a single dose for trichomoniasis to several weeks for rosacea.
- Complete the full course — always finish your prescribed course, even if symptoms improve, to prevent recurrence and antibiotic resistance.
Dosage and Administration
The prescribed dose and duration of metronidazole treatment depend on the type and severity of the infection:
| Condition | Typical dose | Duration |
|---|---|---|
| Bacterial vaginosis | 400mg twice daily or 2g single dose | 5–7 days (or single dose) |
| Trichomoniasis | 2g single dose or 400mg twice daily | Single dose or 5–7 days |
| Dental infection | 200–400mg three times daily | 3–7 days |
| Rosacea | Topical gel/cream applied twice daily | Several weeks |
Metronidazole tablets should be swallowed whole with a glass of water, preferably after eating to minimise stomach upset. Always follow the dosage and duration prescribed by your clinician precisely.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember — unless it is almost time for your next dose. In that case, skip the missed dose and take the next one at the regular time. Never double up doses. Setting a daily alarm on your phone can help prevent missed doses during your course.
Interactions With Other Medications
Always inform your prescriber about all medications you are taking — including over-the-counter medicines, herbal supplements, and vitamins. Key interactions include warfarin (increased bleeding risk), lithium (elevated blood levels), disulfiram (psychotic reaction risk), 5-fluorouracil, and ciclosporin. See the full interactions table in our metronidazole side effects guide.
Pregnancy and Breastfeeding
The use of metronidazole during pregnancy and breastfeeding should be discussed thoroughly with your prescriber. While metronidazole is sometimes used during pregnancy — particularly for treating BV, where untreated infection poses its own risks — it is generally avoided in the first trimester unless absolutely necessary. Metronidazole passes into breast milk; breastfeeding is typically not recommended during treatment and for some time after completing the course. Your prescriber will provide guidance based on your individual circumstances.
Antibiotic Resistance
Overuse or misuse of antibiotics contributes to antibiotic resistance — one of the most significant global health challenges today. When bacteria evolve to resist metronidazole, infections become harder to treat. To minimise this risk: only take metronidazole when prescribed; complete the full course even if you feel better; and never share your medication or self-medicate with leftover antibiotics.
💊 Prescription Antibiotic
Metronidazole
First-line antibiotic for bacterial vaginosis. MHRA-approved oral tablets, prescribed via GPhC-regulated online consultation.
Order Metronidazole →💊 Prescription Vaginal Cream
Dalacin Cream (Clindamycin)
MHRA-approved vaginal cream for BV. Topical clindamycin — targeted action directly at the site of infection.
Order Dalacin Cream →Get Metronidazole for BV Online
Complete a free confidential consultation reviewed by GPhC-registered pharmacist independent prescribers. Metronidazole or Dalacin Cream — discreet next-day delivery.
Treat Bacterial Vaginosis Online →Frequently Asked Questions About Metronidazole
What does metronidazole treat?
Metronidazole treats bacterial vaginosis, pelvic inflammatory disease, trichomoniasis, giardiasis, amoebiasis, C. difficile, dental abscesses, rosacea, and various anaerobic bacterial infections. It is effective against anaerobic bacteria and certain protozoa.
How does metronidazole work?
As a nitroimidazole antibiotic, metronidazole enters bacterial and parasitic cells and creates reactive compounds that damage their DNA, causing cell death. It is particularly effective against anaerobic organisms that thrive in low-oxygen environments.
Can I take metronidazole with food?
Yes — taking metronidazole tablets with or after food helps reduce nausea and stomach upset. Swallow whole with a glass of water. Avoid alcohol entirely during treatment and for 48 hours after.
What should I do if I miss a metronidazole dose?
Take the missed dose as soon as you remember — unless it is almost time for your next dose. In that case, skip the missed dose. Never double up. Set a daily reminder to help maintain consistency.
Is metronidazole effective against viral infections?
No — metronidazole only treats bacterial and parasitic infections. It is ineffective against viruses including colds, flu, and COVID-19. It should only be used when a bacterial or parasitic infection has been confirmed or clinically suspected.
Can I get metronidazole online in the UK?
Yes — Access Doctor is a GPhC-registered online pharmacy. Complete a short confidential online consultation reviewed by GPhC-registered pharmacist independent prescribers. If appropriate, metronidazole is prescribed and dispatched for next-day delivery in discreet packaging.
References
- NICE. Bacterial vaginosis. Clinical Knowledge Summaries. Available at: cks.nice.org.uk/topics/bacterial-vaginosis
- NHS. Bacterial vaginosis. Available at: nhs.uk/conditions/bacterial-vaginosis
- Electronic Medicines Compendium. Metronidazole tablets 400mg — SmPC. Available at: medicines.org.uk/emc
- Electronic Medicines Compendium. Dalacin Cream 2% w/w — SmPC. Available at: medicines.org.uk/emc
- GPhC. Standards for registered pharmacies. Available at: pharmacyregulation.org
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment. Metronidazole and Dalacin Cream are prescription-only medicines — a medical consultation is required before they can be dispensed. In a medical emergency, call 999.