Cefaclor XR

How Does Cefaclor XR Work?

Cefaclor XR works through inhibition of bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) — the enzymes bacteria use to construct and maintain their protective peptidoglycan cell walls. When these proteins are inhibited, the bacteria cannot build or repair their cell wall. The wall degrades under internal osmotic pressure, and the bacteria lyse (burst) and die.

This mechanism is shared across all beta-lactam antibiotics (penicillins, cephalosporins, carbapenems, monobactams). As a second-generation cephalosporin, cefaclor offers improved activity against certain gram-negative organisms — particularly Haemophilus influenzae and Moraxella catarrhalis — compared to first-generation agents like cephalexin.

Resistance to cefaclor occurs primarily through three mechanisms: production of beta-lactamase enzymes that hydrolyze the beta-lactam ring; modification of penicillin-binding proteins (as seen in MRSA); and reduced outer membrane permeability in some gram-negative species. The plasma half-life of cefaclor is approximately 1 hour regardless of formulation, with the XR tablet providing a slower, more sustained release that maintains therapeutic concentrations over the 12-hour dosing interval.

How Hard Is It to Find Cefaclor XR in Stock?

Cefaclor XR presents a moderate findability challenge for patients. While it does not appear on the FDA's official drug shortage list as of 2026, it is not a widely stocked medication at most retail pharmacies. The original brand (Ceclor CD) has been discontinued, leaving only generic versions available from a limited number of manufacturers. Many pharmacies stock Cefaclor XR in small quantities or not at all due to its relatively low prescription volume.

Patients frequently need to call multiple pharmacies or ask for special orders (which typically take 1-3 business days). Independent pharmacies may have better access than large chains. Urban areas with many pharmacy options tend to have better availability than rural locations. The strict food requirement of the XR formulation also means it cannot be simply substituted with immediate-release capsules without a prescriber's guidance on appropriate dose adjustment.

If you're having trouble finding Cefaclor XR at your local pharmacy, medfinder is a paid service that contacts pharmacies near you to check which ones have it in stock, then texts you the results — saving you the time of calling around yourself.

Who Can Prescribe Cefaclor XR?

Cefaclor XR is not a controlled substance, so it does not require DEA scheduling authorization. Any licensed healthcare provider with prescribing authority in their state can prescribe it. There are no REMS (Risk Evaluation and Mitigation Strategy) requirements or special certifications needed.

Types of providers who commonly prescribe Cefaclor XR:

Primary Care Physicians (family medicine, internal medicine)

Nurse Practitioners (NPs) and Physician Assistants (PAs)

Urgent care providers

Pulmonologists (for COPD/chronic bronchitis patients)

Infectious disease specialists

Pediatricians (for patients 16 and older using the ER formulation; IR forms approved for younger children)

Telehealth providers can prescribe Cefaclor XR for most of its indicated conditions (bronchitis, pharyngitis, sinusitis, uncomplicated skin infections) through platforms like Teladoc, MDLive, or Amazon Clinic. More complex conditions (such as ABECB in a patient with advanced COPD) may require in-person evaluation.

Is Cefaclor XR a Controlled Substance?

No. Cefaclor XR is not a controlled substance. It is not scheduled by the DEA and has no recognized potential for abuse or dependence. Any licensed healthcare provider with prescribing authority — including primary care physicians, nurse practitioners, and physician assistants — can prescribe it without any special DEA registration or prescribing restrictions.

As a non-controlled prescription antibiotic, Cefaclor XR prescriptions can be called in, faxed, or electronically sent to any pharmacy. Refills may be permitted depending on the prescriber's discretion and the clinical situation, though antibiotics are generally prescribed for a single course. Transfers between pharmacies are straightforward and do not require special authorization.

Common Side Effects of Cefaclor XR

The most common side effects reported with Cefaclor XR are gastrointestinal in nature. These are usually mild and often improve with continued use:

Diarrhea (most common)

Nausea

Vomiting

Abdominal pain or stomach upset

Mild skin rash

Headache

Vaginal yeast infection (in women)

Serious side effects requiring immediate medical attention:

Severe allergic reactions (anaphylaxis): difficulty breathing, swelling of face/lips/tongue/throat, hives

Clostridioides difficile-associated diarrhea (CDAD): watery or bloody diarrhea, fever, severe cramps — may occur up to 2 months after stopping the antibiotic

Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN): painful blistering rash — rare but life-threatening

Serum sickness-like reaction: rash, joint pain, and fever — more common with cefaclor than other cephalosporins; typically appears 5-7 days into treatment

Seizures: especially at high doses or in patients with renal impairment

Final Thoughts on Cefaclor XR

Cefaclor XR is an effective second-generation cephalosporin antibiotic with a well-established safety profile. When used appropriately for indicated bacterial infections — and taken correctly with food, as a whole tablet — it provides bactericidal activity against common respiratory, skin, and pharyngeal pathogens. Its twice-daily dosing makes it more convenient than the immediate-release formulation for many patients.

The main challenges with Cefaclor XR in 2026 are practical: it can be difficult to find at retail pharmacies due to its relatively low prescription volume, and the retail price without insurance or discounts can be surprisingly high. Patients who know to ask for special orders, use pharmacy discount cards like GoodRx, and explore independent pharmacies will have the best luck accessing this medication. For patients who truly cannot find it, effective alternatives including cefuroxime and cefdinir are available.

If you need help locating Cefaclor XR at a pharmacy near you, medfinder is a paid service that contacts pharmacies on your behalf and texts you results — making the search fast, simple, and effective.