Cefdinir: a practical guide to use, dose, and safety

Cefdinir (brand name Omnicef) is a third‑generation oral cephalosporin antibiotic you’ll commonly see for ear infections, sinusitis, bronchitis, skin infections, and some pneumonia cases. It fights bacteria, not viruses — so it won’t help a cold or the flu. If your doctor prescribes cefdinir, this page gives clear, useful tips on how to take it, what to watch for, and how to avoid problems.

How to take cefdinir

Typical adult dosing is 300 mg every 12 hours or 600 mg once daily, depending on the infection. For children, the usual approach is 7 mg/kg every 12 hours (or 14 mg/kg once daily), with a maximum of 600 mg per day. Always follow your prescriber's instructions — doses can change if kidney function is reduced.

Take cefdinir with or without food. But if you use antacids that contain aluminum or magnesium, or iron supplements, take them at least 2 hours before or after cefdinir. Those products can cut how much antibiotic your body absorbs. Finish the full course even if you feel better, because stopping early can let the infection come back or breed resistant bacteria.

Store the capsules or suspension at room temperature and shake the liquid before each dose. If you miss a dose, take it as soon as you remember unless it’s almost time for the next dose — don’t double up.

Side effects, interactions, and when to call your doctor

The most common side effects are diarrhea, nausea, headache, and rash. Diarrhea that’s severe or watery could be a sign of C. difficile infection — call your doctor right away. A red or orange discoloration of stool can occur if you take iron with cefdinir; this is usually harmless but alarming if you weren’t warned.

If you’ve had a serious allergic reaction to penicillin or other cephalosporins, tell your prescriber. Cross‑reactivity is uncommon but possible. Also mention liver or kidney disease, pregnancy, or breastfeeding so your clinician can adjust treatment.

Drug interactions to remember: antacids and iron reduce absorption, and probenecid can raise cefdinir levels. If you take multiple prescriptions, list them all for your provider or pharmacist.

Want to compare brand vs generic? Generic cefdinir is widely available and works the same as Omnicef. It’s a prescription medicine — avoid unverified online sellers. If ordering meds online, choose pharmacies with clear contact info, proper licensing, and positive reviews. When in doubt, call your clinic or pharmacist.

Questions for your prescriber: Do I need a different dose for my kidneys? How long should I take it for this infection? What should I do if side effects start? Getting those answers up front makes treatment safer and simpler.

Cefdinir is a reliable option for many bacterial infections when used correctly. Keep notes on how you feel during treatment and reach out to your healthcare team if anything seems off.