Likmez Side Effects: What to Expect and When to Call Your Doctor

Likmez (metronidazole oral suspension) is an effective antibiotic, but like all medications, it comes with a range of possible side effects. Most are mild and resolve on their own. But some are serious and require immediate medical attention. This guide covers everything you need to know about Likmez side effects in 2026.

Likmez Boxed Warning: What You Must Know First

Likmez carries a FDA Boxed Warning — the most serious type of drug warning. The warning states:

Metronidazole (the active ingredient) has been shown to be carcinogenic (cancer-causing) in mice and rats in long-term studies. This risk has not been confirmed in humans at standard therapeutic doses, but because of this finding, the FDA requires that Likmez be used only when necessary — not prescribed for minor infections or used longer than needed.

What this means for you: Follow your doctor's prescribed course exactly. Do not take Likmez beyond the prescribed duration or for infections it wasn't prescribed for.

Common Side Effects of Likmez

The following side effects are common and typically mild. They may improve as your body adjusts to the medication:

• Nausea and stomach upset: The most commonly reported side effect. Taking Likmez with food or crackers can help reduce stomach discomfort.
• Diarrhea: Like all antibiotics, Likmez can disrupt normal gut bacteria and cause diarrhea. Mild diarrhea is common; severe or bloody diarrhea may indicate C. difficile — call your doctor.
• Headache: Mild headaches are reported in some patients. Usually manageable with hydration and over-the-counter pain relievers (acetaminophen preferred over NSAIDs).
• Metallic or unpleasant taste: A distinctive metallic taste in the mouth is common with metronidazole. It is temporary and goes away after treatment ends.
• Dizziness: Some patients feel lightheaded or dizzy. Avoid driving or operating machinery until you know how Likmez affects you.
• Dark or discolored urine: Urine may turn dark brown or reddish. This is harmless and caused by metronidazole metabolites — not blood.
• Loss of appetite: Decreased appetite is common, especially with nausea. Try eating small, frequent meals.

Serious Side Effects: Call Your Doctor Immediately

The following side effects are rare but serious. Stop taking Likmez and call your doctor or seek emergency care immediately if you experience:

• Neurological symptoms: Numbness or tingling in hands or feet (peripheral neuropathy), seizures, confusion, encephalopathy, unsteady walking, or slurred speech. Peripheral neuropathy can be persistent if Likmez is not stopped promptly.
• Severe skin reactions (SCARs): Toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), DRESS, or AGEP — serious, potentially life-threatening skin reactions. Symptoms include widespread rash, blistering, skin peeling, fever, or mucous membrane involvement.
• Aseptic meningitis: Rare. Symptoms include severe headache, stiff neck, fever, nausea, vomiting, and sensitivity to light.
• C. difficile-associated diarrhea: Watery or bloody stools, cramping, or fever during or after treatment. Contact your doctor immediately.
• Severe allergic reaction: Hives, itching, swelling of the face or throat, trouble breathing, or rapid heartbeat — seek emergency care.
• Severe liver problems: Particularly in patients with Cockayne syndrome — contraindicated in this population due to risk of fatal liver failure.

The Alcohol Warning: Critical Information

One of the most important warnings with Likmez is the alcohol restriction. Do not drink alcohol or consume products containing propylene glycol while taking Likmez and for at least 3 days after your last dose.

Combining alcohol with metronidazole causes a disulfiram-like reaction: severe nausea, vomiting, flushing, headache, cramping, and rapid heartbeat. This applies to alcohol in medications (cough syrups, mouthwash), not just drinks.

How to Minimize Side Effects

• Take Likmez with food or a light snack to reduce nausea
• Stay well hydrated throughout your course of treatment
• Avoid alcohol completely — including in foods, mouthwash, and medications — during treatment and for 3 days after
• Shake the bottle well before each dose and use a calibrated measuring device — never a household spoon
• Complete the full course even if you feel better — stopping early can allow infection to return and promote resistance
• Discard any unused suspension 10 days after opening the bottle

For a full list of drug interactions and what to tell your doctor before starting Likmez, see: Likmez Drug Interactions: What to Avoid and What to Tell Your Doctor.

If you're having trouble finding Likmez at your pharmacy, medfinder can help locate it near you.