Cefdinir Antibiotic Guide: What It Treats, Dosage & Cost
Cefdinir is a broad-spectrum antibiotic that works against many of the bacteria behind everyday infections — ear infections, sinus infections, strep throat, and skin infections. Here is everything you need to know.
Need a Cefdinir Prescription?
A telehealth provider can evaluate your infection and send a prescription to your pharmacy today.
What Is Cefdinir?
Cefdinir is a third-generation oral cephalosporin antibiotic. Cephalosporins are beta-lactam antibiotics related to penicillin — they work by disrupting the bacteria's ability to build their cell walls, which causes the bacterial cells to break apart and die.
It was originally sold as Omnicef, though that brand has largely been replaced by generic cefdinir. It comes as capsules (300 mg) and as an oral suspension (125 mg/5 mL) for children.
What Infections Does Cefdinir Treat?
| Infection | Typical Patient | Course Length |
|---|---|---|
| Acute otitis media (ear infection) | Children and adults | 5–10 days |
| Acute bacterial sinusitis | Adults and children | 10 days |
| Community-acquired pneumonia | Adults (mild-moderate) | 10 days |
| Pharyngitis / strep throat | Children and adults | 5–10 days |
| Uncomplicated skin infections | Adults and children | 10 days |
| Acute exacerbations of chronic bronchitis | Adults | 5–10 days |
Dosage
Standard adult dosing:
- 300 mg twice daily (every 12 hours) — most infections
- 600 mg once daily — an alternative for pneumonia and skin infections in adults
Children's dosing is weight-based: typically 7 mg/kg every 12 hours or 14 mg/kg once daily for eligible infections.
📌 Cefdinir and iron
Iron supplements — including multivitamins with iron — significantly reduce the absorption of cefdinir. Take cefdinir at least 2 hours before or after any iron-containing product. This includes iron-fortified infant formula. Cefdinir can also turn stools or formula a reddish color — this is harmless and caused by a drug-iron reaction in the gut.
Side Effects & Warnings
- Diarrhea — most common, usually mild
- Nausea and vomiting
- Headache
- Rash — stop and call your provider if a rash develops
- Vaginal yeast infection
🚨 Severe allergic reaction
Like all beta-lactam antibiotics, cefdinir can rarely cause severe allergic reactions (anaphylaxis). Seek emergency care immediately if you develop hives, facial swelling, difficulty breathing, or rapid heart rate after taking cefdinir. Also watch for signs of C. difficile colitis (severe, watery diarrhea after antibiotic use) and contact your provider if it occurs.
Cefdinir and Penicillin Allergy
A common question: Can I take cefdinir if I am allergic to penicillin?
The short answer is: it depends on your allergy. The cross-reactivity rate between penicillins and cephalosporins is low — estimated at about 1–2% for true allergy. Cefdinir has a different side chain structure from penicillin, so the risk is very small. Many providers will prescribe cefdinir to penicillin-allergic patients, especially for milder reported reactions. However, if your penicillin allergy caused anaphylaxis, your provider may choose an entirely different antibiotic class like azithromycin or clindamycin.
Frequently Asked Questions
Is cefdinir better than amoxicillin?
Not necessarily better — different. Amoxicillin is still the first-line choice for most ear, throat, and sinus infections because it is cheaper and has a long track record. Cefdinir is a good alternative when amoxicillin has failed, when the patient has a mild penicillin allergy, or when a broader-spectrum drug is needed. Your provider will choose based on your situation.
How long does cefdinir stay in your system?
Cefdinir has a relatively short half-life of about 1.7 hours. It is largely eliminated from your body within 24 hours of your last dose. This is why it must be taken consistently — twice daily or once daily depending on the dose — to maintain effective levels throughout treatment.
Why did my child's stool turn red on cefdinir?
This is a well-known, harmless side effect. Cefdinir reacts with iron in food, formula, or supplements in the GI tract to create a reddish compound. It does not indicate bleeding or a serious problem. If you stop the iron supplement during the course, the discoloration usually stops. Always mention it to your pediatrician if you are unsure.
Can cefdinir treat a UTI?
Cefdinir is not FDA-approved for UTIs and is generally not a first-line choice. It has limited activity against E. coli, the most common UTI-causing bacteria. Better options for UTIs include nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin. Cephalexin is sometimes used and has better coverage for UTIs than cefdinir.
How much does cefdinir cost without insurance?
Generic cefdinir typically costs $15–$40 for a 10-day course with a free prescription discount card. The exact price depends on the pharmacy and dose. Compare current prices near you at /drug/cefdinir.
Can I get cefdinir prescribed online?
Yes. Many common infections cefdinir treats — ear infections, sinusitis, strep throat — can be evaluated via telehealth. A licensed provider can assess your symptoms and, if appropriate, send a cefdinir prescription to your pharmacy the same day.
Get a Cefdinir Prescription Online
A licensed telehealth provider can evaluate your infection and send your prescription today.