Metronidazole (Flagyl) vs. clindamycin (Cleocin)

What is metronidazole (Flagyl)? What is clindamycin (Cleocin)?

Metronidazole is an antibiotic used to treat Giardia infections of the small intestine, amebic liver abscess, amebic dysentery (infection of the colon causing bloody diarrhea), bacterial vaginosis, trichomonas vaginal infections, carriers of trichomonas (both sexual partners) who do not have symptoms of infection, abscesses (in the liver, pelvis, abdomen, and brain, C. difficile, Helicobacter pylori (H. pylori), acne rosacea, and metronidazole vaginal gel is used to treat bacterial vaginosis.

Clindamycin is an antibiotic used for treating serious infections. It is effective against several types of bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, and Staphylococcus epidermidis, and Propionibacterium acnes. The topical form of clindamycin is used to treat bacterial vaginosis.

What are the side effects of metronidazole (Flagyl) and clindamycin (Cleocin)?

Metronidazole

Flagyl is a useful antibiotic and is generally well tolerated with appropriate use.

The most common and minor side effects include:

Side effects that are uncomfortable, but may become serious include:

Serious side effects of Flagyl are rare and the drug should be stopped if these symptoms appear:

Clindamycin

The most common side effects of clindamycin are

Clindamycin causes Clostridium difficile associated diarrhea (CDAD) because it can alter the normal bacteria in the colon and encourage overgrowth Clostridium difficile, a bacteria which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting clindamycin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

Other serious side effects of clindamycin include:

What is the dosage of metronidazole (Flagyl) and clindamycin (Cleocin)?

Metronidazole

  • Metronidazole may be taken orally with or without food.
  • In the hospital, metronidazole can be administered intravenously to treat serious infections.
  • The liver is primarily responsible for eliminating metronidazole from the body, and doses may need to be reduced in patients with liver disease and abnormal liver function.

Clindamycin

  • The recommended dose for adults for serious infections is 150 to 450 mg every 6 to 8 hours up to a maximum dose of 1.8 grams per day.
  • For pediatric patients the recommended dose is 8 to 20 mg/kg/day divided into 3 or 4 equal doses.
  • To avoid throat irritation, clindamycin should be taken with a full glass of water.

What drugs interact with metronidazole (Flagyl) and clindamycin (Cleocin)?

Metronidazole

  • Alcohol should be avoided because metronidazole and alcohol together can cause severe nausea, vomiting, cramps, flushing, and headache.
  • Metronidazole can increase the blood-thinning effects of warfarin (Coumadin, Jantoven) and increase the risk of bleeding probably by reducing the breakdown of warfarin.
  • Cimetidine (Tagamet) increases blood levels of metronidazole while cholestyramine (Questran, Questran Light) reduces blood levels of metronidazole by reducing its absorption.
  • Metronidazole should not be combined with amprenavir (Agenerase) for treating human immunodeficiency disease (infection with HIV) because amprenavir contains propylene glycol.
  • Metronidazole blocks the breakdown of propylene glycol in the liver leading to accumulation of propylene glycol in blood. Accumulation of propylene glycol could cause seizures, increased heart rate, and lead to kidney failure.
  • Metronidazole increases the blood levels of carbamazepine (Tegretol, Tegretol XR, Equetro, Carbatrol), lithium (Eskalith, Lithobid) and cyclosporine though unknown mechanisms. Serious reactions may occur if these drugs are taken with metronidazole.

Clindamycin

  • Clindamycin may act as a neuromuscular blocker. This means it can increase the action of neuromuscular blocking drugs (for example, pancuronium and vecuronium), which are used during surgery.

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Are metronidazole (Flagyl) and clindamycin (Cleocin) safe to use while pregnant or breastfeeding?

Metronidazole

  • Metronidazole is not used in early pregnancy because of potential adverse effects on the fetus.
  • Metronidazole is excreted in breast milk. Females who are nursing, because of potential adverse effects on the newborn, should not use metronidazole.

Clindamycin

  • The frequency of congenital abnormalities was not increased when pregnant women used clindamycin during the second and third trimesters. Clindamycin should not be used during the first trimester of pregnancy unless it is clearly needed because it has not been properly evaluated during the first trimester of pregnancy.
  • Clindamycin is excreted in breast milk and should not be used by nursing mothers or nursing should be stopped

Summary

Metronidazole (Flagyl) and clindamycin (Cleocin) phosphate vaginal cream are antibiotics used to treat vaginal infections. A difference is metronidazole is taken orally and clindamycin phosphate vaginal cream is used topically (on the skin).

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Medically Reviewed on 12/5/2018
References
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