Medications

Cefdinir (Omnicef and others)

A cephalosporin antibiotic used to treat bacterial infections, including ear infections, sinus infections, pneumonia, and skin infections.

Plan year 2027 · Source: CMS · Checked 2026-10-30

How Medicare covers it

Part D (capsules and oral suspension taken at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

Coverage details
Part B status	No cefdinir row in the CMS Part B Spending by Drug HCPCS file (RY26, data through 2024) — no J-code basis; coverage path is Part D.
Medicare Advantage	Most Medicare Advantage plans that include drug coverage (MAPD plans) use the same formulary-and-tier system; the plan's own drug list decides coverage and copay — check the plan's formulary.
Medicare Supplement (Medigap)	Medicare Supplement (Medigap) plans sold today do not include prescription drug coverage; drug coverage comes from Part D or an MAPD plan.

What it treats

Cefdinir is a cephalosporin antibiotic used to treat bacterial infections caused by susceptible bacteria, including community-acquired pneumonia, acute worsening (exacerbation) of chronic bronchitis, acute maxillary sinusitis, sore throat and tonsil infections (pharyngitis/tonsillitis), uncomplicated skin and skin-structure infections, and, in children, acute bacterial ear infections (otitis media). It treats bacteria only, not viruses.

What it is for, in depth

Cefdinir is a cephalosporin antibiotic used to treat infections caused by bacteria that can be killed by this drug. In adults and teens it treats community-acquired pneumonia, a sudden worsening of chronic bronchitis, acute maxillary sinus infection, sore throat and tonsil infections, and uncomplicated skin infections. In children it also treats acute bacterial ear infections. It treats bacteria only, not viruses. It works by blocking bacteria from building their cell wall, so the bacteria break apart and die. It comes as 300 mg capsules and as an oral liquid, taken by mouth with or without food. For most adult infections the dose is 300 mg every 12 hours or 600 mg once a day, usually for 5 to 10 days depending on the infection. Doses for children are based on body weight.

How it works

It is a cephalosporin (beta-lactam) antibiotic. It kills bacteria by blocking the building of the bacterial cell wall, so the bacteria break apart and die.

How it is taken

Capsules (300 mg) and an oral suspension taken by mouth, with or without food. For most adult infections the label dose is 300 mg every 12 hours or 600 mg once a day, usually for 5 to 10 days depending on the infection; children's doses are based on weight. Take antacids and iron supplements at least 2 hours before or 2 hours after cefdinir, because they block its absorption.

Common side effects

In capsule trials in adults and adolescents, most side effects were mild and went away on their own; stoppages were mostly for stomach and bowel problems, usually diarrhea or nausea, and 0.4% stopped because of rash. Common effects in the trials included diarrhea, nausea, abdominal pain, indigestion, headache, rash, and vaginal yeast infection (vaginitis/moniliasis).

Serious warnings

Like other antibiotics, cefdinir can allow C. difficile to overgrow in the bowel and cause severe, sometimes life-threatening diarrhea (colitis) during or even months after treatment. Serious allergic reactions, including anaphylaxis, and severe skin reactions have been reported with cephalosporin antibiotics. Kidney problems and blood disorders are also described for this drug class.

Who should be careful

Anyone with a serious allergy to cefdinir, other cephalosporins, or penicillins — cross-allergic reactions can occur, and it should not be used if a prior reaction was severe. People with kidney impairment need lower or less frequent doses. Use care with a history of colitis or C. difficile diarrhea.

Major interactions

Aluminum- or magnesium-containing antacids cut cefdinir absorption by about 40% — take cefdinir at least 2 hours before or after the antacid. Iron supplements and iron-fortified foods also cut absorption (about 80% with a 60 mg elemental iron supplement and about 31% with iron-fortified vitamins), so separate them by at least 2 hours as well. Probenecid blocks the kidneys from clearing cefdinir and roughly doubles its levels.

Why it is in its tier

Cefdinir is most often placed on Tier 3. It is listed by 100.0% of Part D plans in the data, and 54.01% of the plans that list it put it on Tier 3. Tier 3 is a higher-cost tier, so your share of the cost is usually higher than on the lower tiers, even though many plans place this drug on a lower tier instead. That split placement is itself part of the picture. The drivers you can see in the data are mixed: cefdinir is a generic antibiotic, not a brand-only drug, but plans do not agree on its place. Its cost level is low. The CMS dashboard puts average spending per beneficiary at $19.06 for 2024. That is a CMS program average, not a copay and not what you will pay at the pharmacy. Individual plans vary, so check your own plan for your exact cost.

Sources

CEFDINIR CAPSULE [PD-RX PHARMACEUTICALS, INC.] — DailyMed
MedlinePlus — National Library of Medicine
MedlinePlus — Cefdinir

What official patient guides say

Cefdinir comes as a capsule and a liquid suspension to take by mouth, with or without food, every 12 or 24 hours for 5 to 10 days, depending on the condition being treated. Take it at around the same times every day, and shake the suspension well before each use so it mixes evenly. If you miss a dose, take it as soon as you remember, but if it is almost time for the next dose, skip it and do not take a double dose. Store the capsules and suspension tightly closed at room temperature, away from excess heat and moisture, and throw away any unused suspension after 10 days.

Source: MedlinePlus — Cefdinir

Part D formulary coverage

Formulary summary
Most common tier	3
Plans listing this drug	5495
Total Part D plans	5495
Share of plans listing it	100
Formularies listing it	286

Tier	Plans
Tier 1	372 plans
Tier 2	2001 plans
Tier 3	2968 plans
Tier 4	154 plans

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

With Medicare Part D
Most common tier	Tier 3
Typical copay	$30 — half of plans charge between $0 and $45
Typical coinsurance	20.0% of the price
Based on	2918 plans that cover this drug · 2027 plan year

Without insurance, the cash benchmark is $0.1076 per unit (CEFDINIR 125 MG/5 ML SUSP) — about $3.23 for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Similar medications

Other medications in the same FDA pharmacologic class (Cephalosporin Antibacterial):

Part D spending averages (2024)

Brand name	Generic name	Total claims 2024	Total spending 2024	Total beneficiaries 2024	Rank by beneficiaries 2024
Cefdinir	Cefdinir	2.314e+06	3.53555e+07	1855308	69

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

5,495 plans from 509 companies list this drug on a formulary for 2027. Search by company or plan name, or filter by tier. Cost sharing is the plan's published amount for this drug's tier in the initial coverage stage (1-month retail supply), where the plan publishes it; a blank means the plan does not publish it.

Company	Plan	Tier	Copay	Coinsurance