Metronidazole is effective against anaerobic bacteria and protozoa.
Before you read
Test yourself first: 3 questions
Question 1 of 3
A client taking metronidazole for a bacterial infection asks the nurse why alcohol must be avoided. Which response by the nurse is correct?
Answer: B. Metronidazole causes a disulfiram-like reaction with alcohol, producing flushing, nausea, vomiting, abdominal cramps, and headache. Clients must avoid all alcohol, including in mouthwash and cough syrups, during therapy and for at least 3 days after. It does not reduce drug levels, cause kidney stones, or change urine color in a dangerous way.
Question 2 of 3
A client taking metronidazole is being discharged. Which instruction is essential to prevent a serious drug interaction?
Answer: B. Metronidazole produces a disulfiram-like reaction (flushing, nausea, vomiting, tachycardia) when combined with alcohol. The client must avoid alcohol during therapy and for at least 3 days after completing the medication.
Question 3 of 3
A nurse is administering an oral antibiotic that must be taken on an empty stomach for proper absorption. Which medication requires this instruction?
Answer: A. Penicillin V and other penicillins (and tetracyclines) are best absorbed on an empty stomach, taken about 1 hour before or 2 hours after meals. Many other drugs are taken with food to reduce GI upset, but the classic teaching for optimal absorption applies to oral penicillin. Amoxicillin can be taken with or without food; metronidazole and nitrofurantoin are taken with food to reduce GI distress.
Keep the streak going with more questions like these, each with a full rationale.
What is metronidazole?
Its hallmark is a severe disulfiram-like reaction with alcohol, so alcohol must be strictly avoided. The key principle is no alcohol during therapy and for at least 48 to 72 hours afterward.
Key points to remember
- Metronidazole is effective against anaerobic bacteria and protozoa.
- It causes a severe disulfiram-like reaction (flushing, severe nausea, vomiting, tachycardia) when combined with alcohol.
- Alcohol must be avoided during therapy and for at least 48 to 72 hours after the last dose.
- It commonly causes a metallic taste, nausea, and harmless darkening of the urine.
- It can potentiate warfarin and increase bleeding risk.
- For trichomoniasis, sexual partners are treated at the same time to prevent reinfection.
Nursing priorities
- Screen for and emphasize complete avoidance of alcohol including in mouthwash and cough syrups.
- Monitor INR in patients taking warfarin and assess for bleeding.
- Assess for and report CNS effects such as numbness, tingling, or seizures.
- Teach that treating sexual partners is needed for trichomoniasis.
- Take with food to reduce GI upset.
Labs & values
Patient teaching
- Do not drink any alcohol during treatment and for at least 3 days after the last dose, and check cough syrups and mouthwash for alcohol.
- Your urine may turn dark, which is harmless, and you may notice a metallic taste.
- If treated for a trichomonas infection, your partner must be treated too.
- Report numbness, tingling, or seizures, and take with food to reduce stomach upset.
Red flags: report now
- Severe flushing, vomiting, and palpitations after alcohol indicate a disulfiram-like reaction and require evaluation.
- Numbness, tingling, or seizures may indicate neurotoxicity and must be reported.
- Increased bruising or bleeding in patients on warfarin should be reported.
References
Clinical references for this topic
