Metronidazole

Metronidazole has been around for a long time for rosacea and usually you hear about the topical gel or cream. However, now metronidazole is being presribed orally for rosacea. You should read about an anecdotal experience of oral metronidazoe:

Siliconmessiah

Siliconmessiah Continued

We will see if we hear more about such treatments being used by other rosaceans and if there are any side effects or risks involved with such oral doses of metronidazole for rosacea.

Note this statement from rxlist.com:
"To reduce the development of drug-resistant bacteria and maintain the effectiveness of Flagyl and other antibacterial drugs, Flagyl should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria."

Warnings and Precautions from rxlist.com

Sudden death due to metronidazole/ethanol interaction.
Cina SJ, Russell RA, Conradi SE.
Division of Surgical Pathology, Johns Hopkins Hospital, Baltimore, MD, USA. ; Am J Forensic Med Pathol. 1996 Dec;17(4):343-6.

Cautions of Metronidazole Use from Medscape

Adverse Reactions from epocrates.com

Precautions and Side Effects from healthcentral.com

Precautionary Drug Insert from intekom.com

Special Precautions:

It is a standard recommendation to avoid alcohol while taking metronidazole, although recent research suggests that the medication might not actually interact significantly with alcohol

Metronidazole can cause seizures. Let your healthcare provider know immediately if you have a seizure while taking this drug.

If you are pregnant or breastfeeding, please note this warning about using Metronidazole:

Metronidazole is considered a pregnancy Category B medication. This means that it is probably safe for use during pregnancy, although the full risks are not known. Talk to your healthcare provider about the risks and benefits of using this drug when pregnant (see Metronidazole and Pregnancy for more information). Currently, it is not recommended that women in their first trimester take metronidazole to treat trichomoniasis (a sexually transmitted infection) or bacterial vaginosis. emedtv.com

Other warnings from emedtv.com:

Metronidazole can worsen a pre-existing yeast infection (such as thrush or a vaginal yeast infection). These yeast infections usually require treatment with an antifungal medication.

If you have liver disease, your body may not metabolize this medication as well as it should. As a result, your healthcare provider will probably recommend a lower metronidazole dosage.

Adverse effects from Wikipedia:

Common adverse drug reactions (≥1% of patients) associated with systemic metronidazole therapy include: nausea, diarrhea, and/or metallic taste in the mouth. Intravenous administration is commonly associated with thrombophlebitis. Infrequent adverse effects include: hypersensitivity reactions (rash, itch, flushing, fever), headache, dizziness, vomiting, glossitis, stomatitis, dark urine, and/or paraesthesia.

High doses and/or long-term systemic treatment with metronidazole is associated with the development of black hairy tongue, leukopenia, neutropenia, increased risk of peripheral neuropathy and/or CNS toxicity

Metronidazole is listed by the International Agency for Research on Cancer (IARC) as a potential human carcinogen. Although some of the testing methods have been questioned, it has been shown to cause cancer in experimental animals. Yet, metronidazole was shown to be safe in humans. It appears to have a fairly low potential for cancer risk and under most circumstances the benefits of treatment outweigh the risk. Metronidazole is banned in the EU for veterinary use in the feed of animals.

Earlier studies suggested a relation between metronidazole and various birth defects. Those studies are nowadays considered flawed and more recent studies "do not support a significant increased risk for birth defects or other adverse effects on the fetus."

Common adverse drug reactions associated with topical metronidazole therapy include local redness, dryness, and/or skin irritation; and eye watering (if applied near eyes). Wikipedia

Interaction with alcohol

Consuming ethanol (alcohol) while using metronidazole has long been thought to have a disulfiram-like reaction with effects that can include nausea, vomiting, flushing of the skin, tachycardia (accelerated heart rate), and shortness of breath, however there are studies calling that notion into question. Consumption of alcohol should be avoided by patients during systemic metronidazole therapy and for at least 48 hours after completion of treatment. However, the mechanism of this reaction in the clinical setting has recently been questioned by some authors, and a possible central toxic serotonin reaction for the alcohol intolerance suggested. Wikipedia

Potentially fatal serotonin syndrome

Recently, according to Wikipedia there have been reported cases of SSRI/SNRI and metronidazole induced serotonin syndrome, this information is not included on the metronidazole patient information leaflet.

Outbreak of Stevens-Johnson syndrome/toxic epidermal necrolysis associated with mebendazole and metronidazole use among Filipino laborers in Taiwan.
Chen KT, Twu SJ, Chang HJ, Lin RS.
Am J Public Health. 2003 Mar;93(3):489-92.

Topical Use of Metronidazole:

Metronidazole cream, gel, and lotion vehicles have similar efficacies. There were no substantial differences between concentrations of 0.75% and 1%, or between once daily and twice daily regimens.

Cumulative irritation potential among metronidazole gel 1%, metronidazole gel 0.75%, and azelaic acid gel 15%