As is the case with any other medication, there may be some instances where metronidazole use is not recommended or usage will have to be adjusted in order to prevent or reduce the risk of negative interactions occurring from other drugs, medical conditions, or even food and drink.
According to the U.S. National Library of Medicine, drugs that may interact with metronidazole include the following:
- Disulfiram – taking metronidazole, frequently used in treatment programs, with disulfiram may cause psychotic reactions
- Alcoholic beverages – taking metronidazole with alcohol can cause abdominal cramps, nausea, vomiting, headaches, and flushing
- Warfarin and other oral anticoagulants – taking metronidazole with anticoagulants (blood thinners) can cause bleeding problems
- Lithium – metronidazole can increase the amount of lithium in the blood to dangerous levels
- Busulfan – using metronidazole can increase the amount of busulfan, a chemotherapy drug that treats certain kinds of leukemia, in the bloodstream
- Drugs that inhibit CYP450 enzymes – taking metronidazole with cimetidine or other drugs that reduce CYP450 enzymes—which are important to the formation and breakdown of molecules and cells inside the body—can cause metronidazole to stay inside the body too long
- Drugs that induce CYP450 enzymes – taking metronidazole with phenytoin, phenobarbital, or other drug that stimulate CYP450 enzymes can cause metronidazole to leave the body too quickly
Please note that this list may not be complete, and other interactions with drugs not listed here may occur.
Metronidazole and Clindamycin
Both metronidazole and clindamycin can treat vaginal infections.
Metronidazole and Tylenol
There are no known drug interactions between metronidazole and acetaminophen, also known as Tylenol. This fact does not necessarily mean that no drug interactions exist, though.
Sometimes the foods and beverages a person consumes can interact with the medications they take.
Food and drink that may interact with metronidazole include:
- Alcohol – using alcohol while on metronidazole can cause abdominal cramps, nausea, vomiting, headaches, and flushing
- Food containing propylene glycol – consuming drink mixes, bread and dairy products, cake mix, dressings, dried soups, popcorn, soft drinks, fast foods, food coloring, and other food containing propylene glycol can cause unpleasant symptoms, such as abdominal cramps, nausea, vomiting, headaches, and flushing
Please note that this list may not be complete, and that other foods and beverages may interact with this metronidazole.
Metronidazole and Wine
Drinking wine or other alcohol while taking metronidazole can cause a disulfiram-like reaction. Disulfiram is a drug that doctors often use to treat drinking problems by creating an unpleasant physical reaction to alcohol. Metronidazole can cause a disulfiram-like reaction to wine or other types of alcohol with symptoms that can include:
- Nausea and vomiting
- Flushing of the skin
- Stomach cramps
- Rapid heart rate
- Chest pain
- Difficulty breathing
When taking wine and metronidazole, it may lead to a worsening of these symptoms.
Disease & Conditions Interactions
Sometimes certain medications can increase the risk of negative side effects for patients with certain diseases or other medical conditions. These conditions and negative side effects include:
- Neurologic toxicity – those with seizure disorders or other nervous system problems can suffer neurological problems, such as seizures, vertigo, confusion, and more after taking this drug
- Colitis – taking this medication can disrupt the balance of beneficial and unhealthy bacteria living in the gut to allow an overgrowth of the toxin Clostridium difficile, which may be a primary cause of antibiotic-associated colitis
- Certain blood disorders – taking this medication with certain blood disorders can cause low white blood cell count (WBC), low platelet count, and poor bone marrow function
- Alcoholism – consuming alcohol while taking this drug can cause nausea and vomiting, sweating, flushing, headache, abdominal cramps, and low blood pressure (hypotension)
- Dialysis – dialysis is a treatment that cleans toxins from the blood in patients whose kidneys no longer work; dialysis can remove metronidazole from the bloodstream before the antibiotic has a chance to work
- Liver disease – the liver breaks down (metabolizes) metronidazole and other substances in the body; liver disease can slow metabolism in a way that allows this drug to build up to dangerous levels
- Sodium restrictions – patients who have high blood pressure (hypertension), congestive heart failure, or fluid retention are often on low-salt diets and other sodium restrictions; the brand of ready-to-use injectable metronidazole, Flagyl I.V. RTU, contains a significant amount of sodium
Please note that this list may not be complete, and there may be other diseases and medical conditions where patients should not take metronidazole.
Metronidazole and Sex
Depending upon your reason for taking metronidazole your doctor may advise you that you should avoid having sex, as intercourse may reduce the strength of the medication, which can prevent it from working properly. Furthermore, the oils in the cream and vaginal gel version may damage the latex in certain contraceptive devices, such as condoms, diaphragms, and cervical caps. Such damage may cause the contraceptive devices to leak, wear out sooner, or otherwise work improperly.
Metronidazole and Pregnancy
For more information, please visit our page on metronidazole and pregnancy risks.