Likmez Drug Interactions: What to Avoid and What to Tell Your Doctor

Likmez (metronidazole oral suspension) is a powerful antibiotic with several clinically significant drug interactions. Some interactions are contraindicated — meaning you must not combine them. Others require monitoring or dose adjustments. Here's what you need to know before starting Likmez.

Critical: Alcohol Is Contraindicated with Likmez

This is the most important interaction to know. Do not drink alcohol or consume propylene glycol during Likmez treatment and for at least 3 days after your last dose.

Metronidazole inhibits aldehyde dehydrogenase, the enzyme that breaks down acetaldehyde (a toxic alcohol metabolite). When alcohol builds up, it causes a disulfiram-like reaction: severe nausea, vomiting, abdominal cramps, flushing, headache, and palpitations.

This includes ALL sources of alcohol:

• Beer, wine, spirits, mixed drinks
• Alcohol-containing medications (some cough syrups, liquid cold remedies, NyQuil, etc.)
• Mouthwash containing alcohol (Listerine and others)
• Propylene glycol-containing products

Critical: Disulfiram (Antabuse) — Contraindicated

Likmez is absolutely contraindicated in patients who have taken disulfiram (Antabuse) within the last 2 weeks. The combination has caused severe psychotic reactions in alcoholic patients, including confusion, hallucinations, and agitation. Tell your doctor if you have ever taken disulfiram.

Major Interaction: Warfarin (Coumadin, Jantoven)

Metronidazole significantly increases the blood-thinning effect of warfarin. This happens because metronidazole inhibits CYP2C9, the liver enzyme responsible for warfarin metabolism. Higher warfarin levels increase bleeding risk.

If you take warfarin, your doctor should monitor your INR (international normalized ratio) more closely during and after Likmez treatment. A warfarin dose reduction is often needed. Do not stop warfarin on your own — always consult your doctor.

Major Interaction: Lithium (Lithobid, Eskalith)

Metronidazole can increase lithium blood levels, raising the risk of lithium toxicity. Signs of lithium toxicity include hand tremor, confusion, diarrhea, nausea, blurred vision, dizziness, and in severe cases — seizures or kidney damage.

If you are on lithium for bipolar disorder or another condition, tell your prescriber before starting Likmez. Lithium levels should be monitored during and after treatment.

Moderate Interaction: Phenytoin (Dilantin)

Metronidazole inhibits the metabolism of phenytoin, an anti-seizure medication. This can lead to elevated phenytoin levels and toxicity symptoms such as dizziness, nausea, double vision, slurred speech, and difficulty with coordination (ataxia).

If you take phenytoin, report any new neurological symptoms during Likmez treatment. Your doctor may want to monitor phenytoin levels.

Moderate Interaction: Lopinavir/Ritonavir Oral Solution

The oral solution form of lopinavir/ritonavir (Kaletra) contains propylene glycol. Combining Likmez with propylene glycol causes the same disulfiram-like reaction as alcohol. If you take lopinavir/ritonavir, use the tablet form (not the oral solution) during Likmez treatment. Consult your HIV specialist.

Additional Interactions to Know

Busulfan: Metronidazole may increase busulfan levels, raising risk of busulfan toxicity (used in some cancer treatments). Avoid combining if possible.

Cyclosporine: May increase cyclosporine levels. Monitor closely if you are on immunosuppressive therapy after organ transplant.

Live bacterial vaccines (e.g., typhoid oral vaccine): Likmez may reduce the effectiveness of live bacterial vaccines. Avoid vaccination with live bacterial vaccines while taking Likmez.

Lab test interference: Metronidazole may interfere with certain lab tests (e.g., some AST, ALT, glucose hexokinase tests), potentially causing false results. Tell all lab personnel and doctors you are on Likmez.

What to Tell Your Doctor Before Starting Likmez

Before starting Likmez, tell your healthcare provider about:

• All prescription medications, including warfarin, lithium, phenytoin, HIV medications
• All OTC medications, herbal supplements, and vitamins
• Any history of liver or kidney disease
• Blood disorders (history of blood dyscrasia)
• Cockayne syndrome diagnosis
• Disulfiram use in the past 2 weeks
• Pregnancy or breastfeeding status

For information on Likmez side effects and when to call your doctor, see: Likmez Side Effects: What to Expect and When to Call Your Doctor.

Struggling to find Likmez at a pharmacy? medfinder can help you locate it near you quickly.