Flagyl vs. Bactrim

Flagyl, Flagyl ER, and Flagyl Injection (metronidazole) and Bactrim (sulfamethoxazole and trimethoprim) are antibiotics used to treat a variety of bacterial infections

Side effects of Flagyl include:

• nausea,
• abdominal cramps,
• stomach upset,
• vomiting,
• diarrhea,
• constipation,
• headache,
• weight loss (anorexia),
• dizziness,
• dry mouth,
• dark-colored urine, or
• a metallic taste in the mouth or changes in taste.

Uncomfortable side effects that may become serious are:

• fevers,
• pain with urination,
• mouth sores,
• tingling or pricking sensations that may become permanent,
• brain disease, and
• seizures.

Serious but unlikely side effects of Flagyl include:

• unsteadiness,
• seizures,
• mood changes,
• numbness or tingling of the hands or feet, and
• painful urination.

Common side effects of Bactrim include:

• loss of appetite,
• nausea,
• vomiting,
• painful or swollen tongue,
• dizziness,
• spinning sensation,
• ringing in your ears,
• tiredness, or
• sleep problems (insomnia).

Tell your doctor if you experience serious side effects of Bactrim including:

• bruising or bleeding,
• aplastic anemia,
• jaundice,
• hepatic necrosis,
• mouth sores,
• joint aches,
• severe skin rashes,
• itching, and
• sore throat.

What is Flagyl?

Flagyl, Flagyl ER, and Flagyl Injection (metronidazole) are antimicrobial drugs used to treat bacterial vaginosis, trichomonas, amebiasis, and anaerobic bacterial infections.

What is Bactrim?

Bactrim (sulfamethoxazole and trimethoprim) DS is a combination of two antibiotics used to treat urinary tract infections, acute otitis media, bronchitis, Shigellosis, Pneumocystis pneumonia, traveler's diarrhea, methicillin-resistant Staphylococcus aureus (MRSA), and other bacterial infections susceptible to this antibiotic.

Flagyl may interact with blood thinners or seizure medications.

Flagyl may also interact with cimetidine, lithium, or disulfiram.

Bactrim may interact with blood thinners or seizure medications.

Bactrim may also interact with antidepressants, cyclosporine, oral diabetes medications, digoxin, diuretics (water pills), indomethacin, leucovorin, calcium folinate, methotrexate, or heart or blood pressure medications.

Flagyl is supplied in 250 and 500 mg strength tablets, Flagyl ER is available in 750 mg strength tablets, and Flagyl Injection in 500 mg strength in a buffered 100 ml vial. Dosage is quite variable and dependent upon the severity of disease and other considerations made by the treating physician. Most of the serious side effects may occur with any of these three preparations of Flagyl. Flagyl may cause liver enzyme levels to increase; lithium and creatinine levels should be checked to avoid lithium toxicity or renal compromise. Alcohol may increase the side effects of Flagyl. Patients on disulfiram should not take Flagyl until they have had a two week interval without taking disulfiram, especially alcoholic patients, to avoid psychotic reactions. Treatment in pregnant women (during first 3 months is not advised) or women who are breastfeeding should only be done if the benefits outweigh the potential problems. Flagyl passes into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding. Except for use in amebiasis, studies in pediatric patients are not available; Flagyl ER has no pediatric studies.

Bactrim is available in tablets in two strengths; 400 mg sulfamethoxazole and 80 mg trimethoprim and the "DS" form which means double strength, 800 mg sulfamethoxazole and 160 mg trimethoprim. Patients should follow their doctor's instructions and take all of the Bactrim prescribed. Patients allergic to sulfa compounds should not take Bactrim. Bactrim may interact with many drugs; the patient and prescribing doctor should be aware of any potential interactions. Bactrim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus; the same situation exists for women who are breastfeeding and their neonates.