Medications

Cefaclor

A cephalosporin antibiotic taken by mouth (capsules, extended-release tablets, or liquid) for bacterial infections such as bronchitis, ear infections, throat and tonsil infections, and urinary infections.

Plan year 2027 · Source: CMS · Checked 2026-10-31

How Medicare covers it

Part D (forms used 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 cefaclor 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

Cefaclor treats infections caused by susceptible bacteria, including middle ear infections (otitis media), lower respiratory tract infections including pneumonia, pharyngitis and tonsillitis (throat infections), urinary tract infections including pyelonephritis and cystitis, and skin and skin-structure infections. It should be used only for infections proven or strongly suspected to be caused by bacteria, and it does not treat viral infections such as the common cold.

What it is for, in depth

Cefaclor is a cephalosporin antibiotic taken by mouth for infections caused by susceptible bacteria. It treats middle ear infections, lower respiratory tract infections including pneumonia, pharyngitis and tonsillitis, which are throat infections, urinary tract infections including pyelonephritis and cystitis, and skin and skin-structure infections. It should be used only for infections proven or strongly suspected to be caused by bacteria, and it does not treat viral infections such as the common cold. Cefaclor kills bacteria by blocking the building of the bacterial cell wall. It comes as a 250 MG oral capsule, a 500 MG oral capsule, a 500 MG extended-release oral tablet taken over 12 HR, and a 50 MG/ML oral suspension. For streptococcal infections, treatment should continue for at least 10 days, as described in the label content.

How it works

Cefaclor is a semisynthetic cephalosporin antibiotic taken by mouth. Like other cephalosporins, it kills bacteria by blocking the building of the bacterial cell wall.

How it is taken

It is a capsule (250 mg or 500 mg) taken by mouth. The usual adult dose is 250 mg every 8 hours; for more severe infections such as pneumonia, or infections caused by less susceptible organisms, the dose may be doubled. The usual children's dose is 20 mg/kg/day divided every 8 hours (40 mg/kg/day for more serious infections, otitis media, or less susceptible organisms, up to a maximum of 1 g/day). For streptococcal (beta-hemolytic) infections, treatment should continue for at least 10 days.

Common side effects

Stomach and bowel symptoms occur in about 2.5% of patients and include diarrhea (1 in 70); nausea and vomiting have been reported rarely. Allergic-type skin reactions, including morbilliform (measles-like) eruptions, occurred in about 1.5% of patients, and itching, hives, and a positive Coombs test each occurred in fewer than 1 in 200 patients. Genital itching and vaginitis occurred in about 1 in 50 patients.

Serious warnings

Serious allergic reactions, including anaphylaxis, Stevens-Johnson syndrome, and toxic epidermal necrolysis, have been reported rarely, and anaphylaxis may be more common in people with a penicillin allergy history — cross-hypersensitivity among beta-lactam antibiotics may occur in up to 10% of patients with a history of penicillin allergy. Serum-sickness-like reactions (rash with joint pain, sometimes with fever) have been reported, more often in children and during a second course. Clostridioides difficile associated diarrhea and pseudomembranous colitis, ranging from mild to life-threatening, have been reported with nearly all antibacterial agents including cefaclor. Several cephalosporins have triggered seizures, particularly in patients with kidney impairment when the dosage was not reduced.

Who should be careful

People with a known allergy to the cephalosporin group of antibiotics must not take cefaclor. People with a penicillin allergy, any drug allergy, a history of stomach or bowel disease (particularly colitis), or markedly impaired kidney function need extra care — older patients are more likely to have reduced kidney function. Safety in infants under 1 month of age has not been established. It should be used during pregnancy only if clearly needed, and caution is advised for nursing mothers.

Major interactions

Probenecid blocks the kidney excretion of cefaclor, as with other beta-lactam antibiotics, raising its blood levels. Increased anticoagulant effect has been reported when cefaclor and oral anticoagulants such as warfarin are given together. Cefaclor can cause a false-positive urine glucose result with Benedict's and Fehling's solutions and with Clinitest tablets.

Why it is in its tier

Cefaclor is most often placed on Tier 3. It is listed by 99.85% of Part D plans, and 55.0% of listing plans put it on Tier 3, which is 3018 of 5487 listing plans. That is a majority, though many plans place it lower, especially on Tier 2. Tier 3 is a middle tier. In general Medicare terms, Tier 1 has the lowest copays, often $0-$15, Tier 3 costs more than the lowest generic tiers, and Tier 5 specialty drugs carry the highest percentage coinsurance. The CMS dashboard shows average spending per beneficiary in 2024 of $98.342246029. That figure is a CMS program average, not a patient's copay, and it shows a low cost level for this generic antibiotic. Its middle-tier placement, rather than the lowest tier, is what the formulary data show across plans, even though cefaclor is a generic medicine and is listed by almost all plans.

Sources

CEFACLOR capsule — DailyMed
MedlinePlus — National Library of Medicine
MedlinePlus — Cefaclor

What official patient guides say

Cefaclor comes as a capsule, an extended-release (long-acting) tablet, and a suspension (liquid) to take by mouth. Take the capsule and liquid with or without food every 8 or 12 hours, and the long-acting tablet within 1 hour of eating a meal every 12 hours (twice a day) for 7 to 10 days, at around the same times every day, exactly as directed. Shake the suspension well before each use, and swallow the long-acting tablets whole; do not split, chew, or crush them. You should begin to feel better during the first few days, and take cefaclor until you finish the prescription, even if you feel better — stopping too soon or skipping doses may leave the infection not completely treated. If you miss a dose, take it as soon as you remember, unless it is almost time for the next dose — then skip it and continue your regular schedule; do not take a double dose. Keep the medication in its container, tightly closed, out of sight and reach of children: store capsules and tablets at room temperature away from excess heat and moisture, not in the bathroom, with the tablets also away from light, and keep the liquid in the refrigerator, tightly closed, disposing of any unused medication after 14 days. Dispose of unneeded medication through a medicine take-back program; do not flush it.

Source: MedlinePlus — Cefaclor

Part D formulary coverage

Formulary summary
Most common tier	3
Plans listing this drug	5487
Total Part D plans	5495
Share of plans listing it	99.85
Formularies listing it	284

Tier	Plans
Tier 1	411 plans
Tier 2	1919 plans
Tier 3	3018 plans
Tier 4	139 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 $44.75
Typical coinsurance	20.0% of the price
Based on	2969 plans that cover this drug · 2027 plan year

Without insurance, the cash benchmark is $0.9627 per unit (CEFACLOR 250 MG CAPSULE) — about $28.88 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
Cefaclor	Cefaclor	9351	532425	5414	1179
Cefaclor ER	Cefaclor	118	34244.1	107	2690

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

5,487 plans from 506 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