Flagyl ER (Metronidazole) Extended-Release Tablets: Prices and Pack Options

Flagyl ER is the extended-release oral tablet form of metronidazole, a nitroimidazole antibiotic and antiprotozoal medicine. We list it in two strengths, 200 mg and 400 mg, with several pack sizes for each, so the real choice in front of you is strength, quantity, and the unit value that goes with each pack. This guide walks through the packages we carry, what the strengths and quantities mean for a prescribed course, and how ordering, prescription status, and delivery work for UK customers.

Your Real Choice: Strength, Pack Size, and Value

Because Flagyl ER is supplied as a tablet taken by mouth, the decision we present is straightforward: which strength has been prescribed and how many tablets are required for the planned course. Our pack quantities are counted in pills, so every pack contains a stated number of tablets rather than a volume or a pre-set course bundle. This makes it easy to compare quantities, but the lowest unit price should not take priority over obtaining the correct prescribed amount.

Our Available Packages and Unit Value

We currently offer 200 mg Flagyl ER in packs of 120, 180, 270, or 360 pills, and 400 mg Flagyl ER in packs of 90, 120, 180, 270, or 360 pills. Pack prices and the resulting price per pill vary by quantity. The comparison below sets out the exact price, unit value, and relative saving for each 400 mg pack size we carry, so you can weigh total cost against price per pill while keeping the prescribed quantity in view.

We calculate unit value consistently across every pack size we list, so the figures above reflect our own current pricing only. A lower price per pill is one useful factor among several; it should be considered alongside the prescribed course length, the number of tablets that will actually be used, the expiry date, and appropriate storage. Antibiotics should not be bought as speculative stock for an unassessed future infection.

Which Flagyl ER Strength and Quantity Fits Your Prescription?

Metronidazole dosing is determined by the infection being treated, age and body weight where relevant, liver function, and other individual clinical factors. The 200 mg and 400 mg strengths allow different prescribed doses to be supplied; they are not simply interchangeable options. Do not replace a prescribed 400 mg tablet with two 200 mg tablets, or make any other strength substitution, unless a prescriber or pharmacist has confirmed that it is appropriate for the exact product and regimen. Extended-release tablets must not be split, crushed, or chewed.

• Confirm whether the prescribed strength is 200 mg or 400 mg before selecting a pack.
• Count the total number of tablets required for the complete prescribed course and choose an available pack accordingly.
• Follow the prescribed dosing frequency rather than assuming that every metronidazole regimen is the same.
• Do not keep leftover antibiotic tablets for self-treatment of a later illness; ask a pharmacist how unwanted medicine should be disposed of.

The table below sets out the pack-size options available for each strength we carry, separately from pricing, so you can see at a glance which quantities exist for 200 mg compared with 400 mg.

Flagyl ER, Generic Metronidazole, and Related Antibiotic Options

Flagyl ER is a branded extended-release presentation of metronidazole. The active ingredient is the same substance found in other metronidazole medicines, but release characteristics, dosing schedules, strengths, and administration instructions can differ between formulations. Standard-release and extended-release tablets should therefore not be substituted without professional confirmation. For information about antibiotics with different antibacterial spectra, see Amoxil and Augmentin. These penicillin-class antibiotics are not direct substitutes for metronidazole. You can also browse Antibiotics for related options.

What Flagyl ER Is Used For

Metronidazole is active against susceptible anaerobic bacteria and certain protozoal organisms. Depending on the formulation and prescribed regimen, it may be used for conditions including bacterial vaginosis, trichomoniasis, giardiasis, amoebiasis, some dental infections, and certain intra-abdominal or pelvic infections. It can also form part of a combination regimen for Helicobacter pylori eradication. Not every metronidazole formulation or dosing schedule is suitable for every one of these conditions, so the indication for this extended-release tablet should be confirmed by a prescriber. Readers researching bacterial vaginosis or trichomoniasis treatment can also visit our Woman's Health section.

How Metronidazole Works and How Flagyl ER Should Be Taken

Inside susceptible anaerobic bacteria and protozoa, metronidazole is converted into reactive compounds that damage DNA and disrupt nucleic-acid synthesis. Human cells are much less likely to activate metronidazole through this pathway, which helps provide its selective antimicrobial effect. Take Flagyl ER exactly as directed and at a consistent time. Extended-release metronidazole regimens are often designed for once-daily administration, but the exact frequency and course length depend on the product and condition being treated.

Flagyl ER tablets should be swallowed whole and must not be split, crushed, or chewed, because damaging the tablet can alter the way the medicine is released. Extended-release metronidazole is generally taken on an empty stomach, at least one hour before or two hours after food, unless the product leaflet or prescriber gives different instructions. Complete the prescribed course even if symptoms improve earlier. If a dose is missed, follow the patient information leaflet or ask a pharmacist; do not take a double dose unless specifically instructed.

Safety, Interactions, and Who Should Take Extra Care

Common metronidazole side effects include nausea, diarrhoea, abdominal discomfort, headache, and a metallic taste. Alcohol should be avoided during treatment and for the period stated in the product leaflet after the final dose, commonly at least 48 hours, because the combination may cause nausea, vomiting, flushing, abdominal discomfort, headache, or palpitations. Metronidazole can increase the effect of warfarin and related anticoagulants and can interact with lithium, disulfiram, busulfan, ciclosporin, and enzyme-inducing anticonvulsants such as phenytoin or phenobarbital. A prescriber or pharmacist should check the full medicine list before treatment begins.

Stop taking the medicine and seek medical advice promptly if serious neurological symptoms develop, including confusion, seizures, marked unsteadiness, visual changes, or persistent numbness, tingling, or burning pain in the hands or feet. Longer or repeated courses may require clinical review and, in some circumstances, blood-count or liver-function monitoring. People with significant liver disease, active neurological disorders, or blood disorders should ensure that the prescriber is aware of their history.

• Pregnancy: UK guidance advises that metronidazole should be used in pregnancy only when a prescriber judges it necessary, with high single-dose regimens avoided, particularly in the first trimester.
• Breastfeeding: metronidazole passes into breast milk. Use may be compatible with breastfeeding, but the infant should be monitored for gastrointestinal upset, oral thrush, poor feeding, or rash, and large single doses should be avoided.
• Children: oral metronidazole is used in children, including infants over 1 month, but dosing is age- and weight-specific. An extended-release tablet may not be suitable for a child who cannot swallow it whole.
• Driving: dizziness, drowsiness, confusion, hallucinations, seizures, or visual disturbance can impair driving. Do not drive or operate machinery if affected.

Metronidazole should not be used by anyone with a known hypersensitivity to metronidazole, another nitroimidazole, or an excipient in the particular tablet. Metronidazole is authorised for human medicinal use in the United Kingdom; this describes the active ingredient rather than the approval status of any individual brand, strength, or pack.

Prescription Status and Access in the United Kingdom

In the UK, metronidazole in this dosage form is classified as a prescription-only medicine. This classification applies to the medicine and dosage form rather than to a particular pack size. Under our ordering policy, we do not require you to upload or send us a prescription before we accept an order for Flagyl ER. Our checkout requirement does not change the medicine's underlying prescription-only classification, and a prescriber's assessment remains the appropriate way to confirm the indication, formulation, dose, and course length for an individual patient.

Ordering, Delivery, and Receiving Your Flagyl ER Order

We have operated as an online pharmacy catalogue since 2018. Our support team is available 24 hours a day by email and online chat, with a pharmacist available to answer questions about your order. Once you choose a strength and pack size, our checkout confirms the exact option selected before payment, and we pack and dispatch orders for delivery to UK addresses.

• Choose the prescribed strength, 200 mg or 400 mg, and an available pack size that covers the prescribed quantity.
• Review the exact price, strength, and pack details at checkout before confirming payment.
• Contact our support team by email or online chat if you have questions before or after ordering.
• Check your delivery confirmation for dispatch and arrival details once your order has been placed.

Storing Flagyl ER Safely

Flagyl ER tablets should be stored at 20°C to 25°C in a tightly closed, light-resistant container, protected from light and kept out of the sight and reach of children. Leave the tablets in their supplied packaging unless the dispensing instructions state otherwise. Check the expiry date printed on the pack before use, and do not take tablets that are expired, damaged, or stored incorrectly. A pharmacist can advise on safe disposal of unwanted tablets.

Making the Best-Value Choice for Your Order

The right pack size balances three things: the exact strength prescribed, the number of tablets required for the course, and the price per pill shown in the package comparison above. A larger pack may have a lower unit price, but it is not better value if it leaves unnecessary antibiotic tablets unused. Compare the available quantity with the prescribed total, check the formulation and strength carefully, and review the final price and pack details before checkout. This keeps the choice focused on an appropriate course rather than on unit price alone.