Metronidazole 250mg Tablets

Metronidazole is a nitroimidazole antimicrobial. It acts as a prodrug that is activated by reduction of its nitro group by anaerobic organisms and certain protozoa. This reduction forms reactive cytotoxic compounds that bind to and damage DNA, leading to inhibition of nucleic acid synthesis and cell death.

Urgent Side Effects: Seek Medical Help Right Away

Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek medical attention:

Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Redness or white patches in the mouth or throat
Vaginal itching or discharge
Fast or abnormal heartbeat
Pain when passing urine or blood in urine
Passing urine more often
Pelvic pain
Ringing in the ears, hearing loss, or other changes in hearing

Nervous System Problems

This medication can cause nervous system problems, which may be long-lasting. If you experience any of the following symptoms, contact your doctor right away:

Burning, numbness, or tingling sensations that are not normal
Changes in balance or eyesight
Dizziness or fainting
Headache
Insomnia
Seizures
Trouble speaking
Confusion
Depression
Irritability
Fatigue
Weakness

Aseptic Meningitis

This medication may increase the risk of a severe brain problem called aseptic meningitis. If you experience any of the following symptoms, contact your doctor right away:

Headache
Fever
Chills
Severe nausea or vomiting
Stiff neck
Rash
Sensitivity to light
Drowsiness
Confusion

Low White Blood Cell Counts

This medication can cause low white blood cell counts, which may increase the risk of infection. If you experience any of the following symptoms, contact your doctor right away:

Fever
Chills
Sore throat

Severe Skin Reactions

This medication can cause severe skin reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and other serious reactions. If you experience any of the following symptoms, seek medical help right away:

Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in the mouth, throat, nose, eyes, genitals, or skin
Fever
Chills
Body aches
Shortness of breath
Swollen glands

Other Side Effects

Most people do not experience serious side effects, but some may occur. If you experience any of the following symptoms, contact your doctor if they bother you or do not go away:

Constipation
Diarrhea
Stomach pain
Upset stomach
Vomiting
Decreased appetite
Stomach cramps
Metallic taste
Headache
Joint pain
* Decreased libido

Reporting Side Effects

If you have questions about side effects or want to report any side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have Cockayne syndrome, as some individuals with this condition have developed liver problems while taking this medication. In some cases, these liver issues have been severe, persistent, or even fatal.
If you have taken disulfiram within the past 14 days.
If you are less than 12 weeks pregnant, as this medication is not intended for use in certain patients during this stage of pregnancy.

This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health issues with your doctor and pharmacist. They will help determine whether it is safe to take this medication in combination with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.

As this medication may interfere with certain laboratory tests, it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this drug. If you are undergoing dialysis, consult with your doctor to discuss any necessary precautions.

To minimize potential interactions, you may need to avoid consuming alcohol or products containing alcohol or propylene glycol during treatment with this medication and for at least 72 hours after your last dose. Examples of products that may contain alcohol or propylene glycol include some cough syrups. Consuming these substances may cause adverse effects such as stomach cramps, nausea, vomiting, headaches, and flushing. Consult with your doctor to determine if you need to avoid alcohol or products containing alcohol or propylene glycol.

Do not exceed the recommended treatment duration, as this may increase the risk of a secondary infection. If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.

If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor to discuss the potential benefits and risks of this medication to both you and your baby.

• Alcohol (including alcohol-containing products like cough syrups, mouthwash) - disulfiram-like reaction (abdominal cramps, nausea, vomiting, headaches, flushing)
• Disulfiram - psychotic reactions

• Warfarin (and other oral anticoagulants) - increased anticoagulant effect (monitor INR/PT)
• Lithium - increased lithium levels (monitor lithium levels)
• Busulfan - increased busulfan levels (increased toxicity)
• Phenytoin - increased phenytoin levels, decreased metronidazole levels
• Phenobarbital - decreased metronidazole levels

• Cimetidine - decreased metronidazole clearance (increased metronidazole levels)
• Fluorouracil - increased fluorouracil toxicity
• Cyclosporine - increased cyclosporine levels (monitor cyclosporine levels)
• Tacrolimus - increased tacrolimus levels (monitor tacrolimus levels)

• Oral contraceptives - theoretical reduction in efficacy (use alternative contraception)

• Nausea
• Vomiting
• Diarrhea
• Metallic taste
• Headache
• Dizziness
• Peripheral neuropathy (numbness, tingling, weakness in extremities)
• Seizures
• Rash
• Darkening of urine
• Signs of candidiasis (oral thrush, vaginal yeast infection)

Metronidazole is generally considered safe for use during the second and third trimesters of pregnancy when clearly needed. Use in the first trimester is generally avoided unless the benefits outweigh the potential risks, due to some conflicting data regarding teratogenicity, though most studies do not show an increased risk of birth defects.

Metronidazole is excreted into breast milk in concentrations similar to maternal plasma. The American Academy of Pediatrics considers it compatible with breastfeeding. For single high doses (e.g., 2g for trichomoniasis), some experts recommend pumping and discarding breast milk for 12-24 hours after the dose to minimize infant exposure. For multi-dose regimens, monitor the infant for gastrointestinal upset (diarrhea, candidiasis) or metallic taste aversion.

Dosing is weight-based. Use with caution in neonates due to immature hepatic function and prolonged half-life. Monitor for adverse effects, especially neurological. Safety and efficacy for some indications (e.g., C. difficile) are well-established.

No specific dose adjustment is typically needed based on age alone, but elderly patients may have reduced hepatic or renal function, requiring dose adjustments based on impairment. They may also be more susceptible to neurological adverse effects (e.g., peripheral neuropathy). Monitor closely for adverse reactions.

• Metronidazole is effective against anaerobic bacteria and certain protozoa (e.g., Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica).
• The metallic taste is a common and often bothersome side effect.
• Warn patients explicitly about the disulfiram-like reaction with alcohol; this is a critical patient education point.
• Darkening of urine (reddish-brown) is a harmless side effect due to metabolites.
• For C. difficile infection, metronidazole is typically used for mild-to-moderate cases or as an alternative to vancomycin.
• Prolonged use (especially >10-14 days) or high doses increase the risk of peripheral neuropathy; monitor for symptoms.
• Can cause a false-negative result in the Treponema pallidum immobilization test for syphilis.

• Clindamycin (for anaerobic infections, bacterial vaginosis)
• Tinidazole (for trichomoniasis, giardiasis, amebiasis - similar class, longer half-life)
• Vancomycin (oral, for C. difficile infection)
• Doxycycline (for bacterial vaginosis, some anaerobic infections)
• Secnidazole (for bacterial vaginosis, trichomoniasis - single dose)

If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.