Flagyl 400mg (Metronidazole) — Uses, Dosage, Side Effects Pakistan
- Flagyl = metronidazole, effective against anaerobic bacteria and parasites
- Common uses: amoebiasis, giardiasis, bacterial vaginosis, dental abscess
- Absolutely no alcohol — causes a severe, potentially fatal reaction
- Stomach upset and metallic taste are common side effects
- Avoid in the first trimester of pregnancy
What Is Flagyl?
Flagyl is Sanofi-Aventis's brand name for metronidazole. It is an antibiotic and antiparasitic agent that works specifically against anaerobic bacteria (those that thrive in oxygen-free environments) and parasites.
| Generic name | Metronidazole |
| Drug class | Nitroimidazole antibiotic |
| Available forms | 200 mg, 400 mg, 500 mg tablets; syrup; IV; vaginal gel |
| OTC availability | Prescription only |
| Price in Pakistan | ~150–250 PKR for 14 tablets |
What Is Flagyl Used For?
1. Amoebiasis (Very Common in Pakistan)
Intestinal infection caused by Entamoeba histolytica — spread through contaminated food and water. Symptoms: bloody diarrhoea, stomach pain. Peaks during Pakistan's hot summer months.
2. Giardiasis
Giardia parasite — causes chronic diarrhoea, gas, bloating, and weight loss.
3. Bacterial Vaginosis (BV)
Vaginal odour and discharge in women — treated with Flagyl tablet or gel.
4. Trichomoniasis
A sexually transmitted infection — both partners must be treated simultaneously.
5. Dental Infections
Tooth abscess and gum disease — often combined with Augmentin.
6. C. Difficile Colitis
Severe diarrhoea following antibiotic use.
7. H. Pylori (Stomach Bacteria)
Used in triple therapy: Risek + Amoxicillin + Flagyl.
8. Surgical Prophylaxis
Pre-operative protection before bowel surgery.
Dosage
| Amoebiasis | 800 mg three times daily for 5–10 days |
| Giardiasis | 2 grams once daily for 3 days OR 400 mg three times daily for 5 days |
| Bacterial Vaginosis | 400 mg twice daily for 7 days |
| Trichomoniasis | 2 grams as a single dose OR 400 mg twice daily for 7 days |
| Dental infection | 400 mg three times daily for 5 days |
Take with food — this reduces stomach upset. Always complete the full course.
Side Effects
Common:
- Nausea, vomiting
- Metallic taste in the mouth (a signature side effect of metronidazole)
- Headache
- Loss of appetite
- Dark-coloured urine
- Furry tongue
Serious (Rare):
- Severe allergic reaction
- Peripheral neuropathy (with long-term use)
- Seizures
- Stevens-Johnson syndrome
CRITICAL WARNING: No Alcohol Whatsoever
Disulfiram-like reaction: Drinking alcohol during Flagyl treatment or within 48 hours of the last dose causes:
- Severe nausea and vomiting
- Intense headache
- Flushing and sweating
- Rapid heartbeat (palpitations)
- Dangerous drop in blood pressure
- In severe cases, death is possible
Also check cough syrups and mouthwashes — many contain alcohol as an inactive ingredient.
Loose stools, suspected amoebiasis, or a bacterial infection? Get the right diagnosis and prescription on Ilaaj AI — without leaving home.
Chat with AI Doctor NowPregnancy and Breastfeeding
- First trimester: Avoid — risk of harm to fetal development
- 2nd and 3rd trimesters: May be used under a doctor's supervision
- Breastfeeding: Avoid feeding for 12–24 hours after a single high dose (2g)
Drug Interactions
- Warfarin: Increased bleeding risk
- Lithium: Risk of toxicity
- Phenytoin: Increases phenytoin levels
- Disulfiram: Risk of psychosis
Available Brands in Pakistan
- Flagyl (Sanofi-Aventis) — original brand
- Generic metronidazole
- Metsil (Sami Pharmaceuticals)
- Trichozole
Conclusion
Flagyl (metronidazole) is Pakistan's workhorse antibiotic for amoebiasis, giardiasis, and dental infections. Use it only with a doctor's prescription, complete the full course, and absolutely no alcohol — not during treatment, and not for 48 hours afterwards. For an accurate diagnosis before starting any antibiotic, consult a doctor on Ilaaj AI — from home.
Frequently Asked Questions
What is Flagyl tablet used for?
Flagyl (metronidazole) is an antibiotic effective against anaerobic bacteria and parasites. Common uses in Pakistan include amoebiasis (bloody diarrhoea), giardiasis, bacterial vaginosis, trichomoniasis, dental infections, H. pylori (stomach bacteria), and C. difficile colitis. It is a prescription-only medicine. Always complete the full course.
What is the dosage of Flagyl?
Amoebiasis: 800 mg three times daily for 5–10 days. Giardiasis: 2 grams once daily for 3 days. Bacterial vaginosis: 400 mg twice daily for 7 days. Trichomoniasis: 2 grams as a single dose. Dental infection: 400 mg three times daily for 5 days. Take with food. A doctor will adjust the dose based on your specific condition.
Why can't you drink alcohol with Flagyl?
Flagyl combined with alcohol causes a disulfiram-like reaction — severe nausea, vomiting, headache, flushing, rapid heartbeat, and a dangerous drop in blood pressure. In severe cases it can be fatal. This applies during treatment and for 48 hours after the last dose. Also check cough syrups and mouthwashes for hidden alcohol.
What are the side effects of Flagyl?
Common: nausea, vomiting, metallic taste in the mouth (a signature side effect), headache, loss of appetite, dark-coloured urine, furry tongue. Serious but rare: peripheral neuropathy with long-term use, seizures, severe allergic reactions. Taking Flagyl with food reduces stomach upset.
Is Flagyl safe during pregnancy?
Avoid in the first trimester — risk of harm to fetal development. In the 2nd and 3rd trimesters it may be used under a doctor's supervision for severe infections. During breastfeeding: avoid feeding for 12–24 hours after a single high dose (2g). Topical vaginal gel is preferred for bacterial vaginosis during pregnancy.
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