Keflex (cephalexin) is most often prescribed for infections caused by susceptible gram-positive and some gram-negative bacteria. Typical indications include skin and soft tissue infections such as cellulitis, impetigo, and wound infections; upper and lower respiratory tract infections like pharyngitis, tonsillitis, and bronchitis when bacterial causes are suspected; otitis media (middle ear infection); uncomplicated urinary tract infections; and certain bone infections when appropriate. Clinicians select Keflex when the likely pathogens (for example Staphylococcus aureus and Streptococcus species) are known or suspected to be sensitive to a first-generation cephalosporin. Laboratory cultures and susceptibility testing help confirm effectiveness and guide therapy when needed.
Dosing of Keflex depends on the type and severity of infection, patient age, weight, and kidney function. For many adults with uncomplicated infections, common regimens are 250 mg every 6 hours or 500 mg every 12 hours; clinicians may increase to 1,000 mg per day in divided doses for more severe infections, with a typical maximum daily dose not exceeding 4 grams. Pediatric dosing is weight-based—commonly 25 to 50 mg/kg/day divided into doses every 6 to 12 hours—so accurate weight measurement is essential. For reconstituted oral suspension, shake well and use an accurate dosing device. Complete the full prescribed course even if symptoms improve early; stopping antibiotics prematurely can lead to treatment failure and resistance.
Adjustments are necessary in renal impairment because cephalexin is primarily eliminated by the kidneys. Patients with reduced creatinine clearance should receive lower doses or extended dosing intervals; specific adjustments should be guided by a prescriber familiar with renal dosing. If you have any uncertainty about dosing—especially for infants, elderly patients, or those with kidney disease—consult a healthcare professional before taking Keflex.
Before taking Keflex, inform your healthcare provider of any allergies to cephalosporins, penicillins, or other beta-lactam antibiotics. Although cross-reactivity between penicillins and cephalosporins is lower than once thought, a history of severe penicillin allergy (anaphylaxis) warrants careful evaluation and may contraindicate use. Tell your provider about kidney disease, liver disease, gastrointestinal disorders (including a history of colitis), seizure disorders, pregnancy or breastfeeding, and all other medications and supplements you take.
Monitor for gastrointestinal symptoms during treatment: cephalexin can disrupt normal gut flora and, in some cases, trigger Clostridioides difficile-associated diarrhea. If you experience severe or persistent diarrhea, abdominal cramping, or bloody stools, seek medical attention promptly. Use antibiotics only when clearly indicated—overuse increases the risk of resistance and adverse effects.
Keflex is contraindicated in patients with a known hypersensitivity to cephalexin or other cephalosporins. Exercise caution in individuals with a history of severe allergic reactions to penicillins; discuss risks and alternative antibiotics with your clinician. Additionally, if you have a history of severe gastrointestinal disease such as colitis associated with prior antibiotic use, cephalexin should be used cautiously or avoided. Always disclose all prior adverse drug reactions to ensure safe prescribing.
Common side effects of Keflex are generally mild and include gastrointestinal complaints—nausea, vomiting, abdominal pain, and diarrhea—and less commonly, dizziness, fatigue, or headache. Skin reactions such as rash or itching may occur; if you develop hives, swelling of the face or throat, difficulty breathing, or any sign of anaphylaxis, seek emergency care immediately.
Serious but less common adverse effects include antibiotic-associated colitis (Clostridioides difficile infection), liver enzyme elevations, blood count abnormalities such as neutropenia or thrombocytopenia, and rare cases of kidney dysfunction. If you notice jaundice, persistent fever, unusual bleeding or bruising, or dark urine, contact your healthcare provider. Report any unexpected or severe reactions promptly so therapy can be adjusted.
Cephalexin has relatively few major drug interactions, but a few are clinically important. Probenecid can raise blood levels of cephalexin by decreasing renal excretion, potentially increasing risk of toxicity; dosing adjustments may be needed if both are used. Concurrent use with nephrotoxic agents such as certain aminoglycoside antibiotics or high-dose loop diuretics can increase the risk of kidney injury; monitor renal function closely.
Anticoagulant therapy (e.g., warfarin) may be affected by antibiotics, including cephalosporins, sometimes increasing bleeding risk; clinicians may monitor INR more frequently during coadministration. While evidence is limited, severe diarrhea from antibiotic use can interfere with oral contraceptive effectiveness—use additional contraception if concerned. Always provide a full medication list to your clinician to assess interactions before starting Keflex.
If you miss a dose of Keflex, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose—do not double up to catch up. Doubling doses can increase side effect risks without improving effectiveness. Maintain regular dosing intervals as prescribed to sustain effective antibiotic levels and optimize treatment outcomes.
In the event of an overdose, symptoms may include severe gastrointestinal upset (nausea, vomiting, diarrhea), and in patients with renal impairment, neurologic symptoms such as lethargy, confusion, or seizures may occur due to accumulation. If an overdose is suspected, seek immediate medical attention or contact a poison control center. Treatment is primarily supportive: gastrointestinal decontamination may be considered shortly after ingestion, and hemodialysis can remove cephalexin in severe cases or in patients with significant renal failure.
Store capsules and tablets of Keflex at room temperature, protected from light and moisture, and kept out of reach of children. Do not store in the bathroom. Reconstituted oral suspension typically requires refrigeration and should be used within the timeframe specified on the label (often 7–14 days); always follow the pharmacy’s instructions for storage and discard any unused suspension after the recommended period. Proper storage helps maintain potency and safety.
In the United States, Keflex is classified as a prescription-only medication; it should only be used after an appropriate clinical assessment confirms a bacterial infection likely to respond to cephalexin. Southwest Georgia Regional Medical Center offers a legal and structured pathway for patients needing timely access to Keflex without a prior external prescription. Through clinician-led evaluations—either in-person or via telemedicine—and established standing orders or on-site prescriptive authority, eligible patients receive a medical assessment, appropriate counseling about risks and benefits, and medication dispensed when clinically indicated. This approach ensures safe, evidence-based use while maintaining compliance with state and federal regulations.
Patients seeking Keflex through Southwest Georgia Regional Medical Center should expect a documented medical evaluation that includes a review of allergies, current medications, medical history, and any necessary diagnostic testing. This process protects patient safety, reduces inappropriate antibiotic use, and provides continuity of care. If Keflex is not appropriate, clinicians will recommend alternative therapy or referral as needed. Always follow the center’s guidance and report any adverse reactions or concerns during or after treatment.
Keflex is the brand name for cephalexin, an oral first‑generation cephalosporin antibiotic. It kills bacteria by interfering with cell wall synthesis, which is effective against many gram‑positive bacteria and some gram‑negative species.
Keflex is often used for skin and soft tissue infections (like cellulitis and infected wounds), uncomplicated urinary tract infections, ear infections, throat infections caused by susceptible bacteria, and some bone infections when appropriate.
Keflex can be taken with or without food; taking it with food may reduce stomach upset. Follow the prescribed dose schedule exactly and complete the full course even if symptoms improve.
Common side effects include gastrointestinal symptoms (nausea, vomiting, diarrhea), headache, and sometimes mild allergic skin rashes. Most side effects are mild and resolve after stopping the drug.
Serious but rare effects include severe allergic reactions (anaphylaxis), Clostridioides difficile–associated diarrhea, severe skin reactions, and abnormal liver or kidney test results. Seek immediate care for signs of severe allergy, high fever with diarrhea, or jaundice.
Cross‑reactivity exists but is lower than historically thought. Many patients with non‑severe penicillin allergies can tolerate cephalosporins, but people with a history of immediate, severe penicillin anaphylaxis should consult an allergist or prescriber before taking Keflex.
Keflex is generally considered low risk in pregnancy (category info varies by region) but should only be used when clearly needed and prescribed by a clinician. Small amounts pass into breast milk; most experts consider it compatible with breastfeeding, but discuss with your provider.
Yes. Keflex is commonly used in pediatrics for appropriate infections; dosing is weight‑based. Always use a pediatric dose and formulation provided or confirmed by a healthcare professional.
Dosing depends on the infection and patient factors (age, weight, kidney function). Do not change or stop dosing without medical advice; stopping early can lead to relapse or resistance even if you feel better.
Cephalexin has relatively few drug interactions but can interact with probenecid (extends levels) and may affect oral contraceptive efficacy minimally in rare cases. Always tell your clinician about all medications and supplements you take.
Take the missed dose as soon as you remember unless it’s almost time for the next dose; do not double up doses. Maintain the regular schedule thereafter.
Store at room temperature away from moisture and heat. Dispose of unused antibiotics per local guidelines—do not flush medications or simply throw them in household trash when avoidable.
Yes. Misuse or overuse of Keflex can contribute to antibiotic resistance. Use only when prescribed, take the full course, and avoid antibiotics for viral illnesses.
See your doctor if symptoms worsen, if you develop high fever, severe diarrhea (especially with blood), signs of allergic reaction (hives, swelling, breathing difficulty), or signs of liver/kidney problems (jaundice, dark urine, reduced urine output).
Yes. Patients with significant kidney impairment often need dose adjustments or extended dosing intervals. Elderly patients may also require monitoring and adjustment. Your prescriber will tailor dosing based on kidney function.
Both are oral first‑generation cephalosporins with similar spectra. Cefadroxil has a longer half‑life, allowing less frequent dosing (often once or twice daily), which can aid adherence; effectiveness for many infections is comparable.
Cefazolin is an injectable first‑generation cephalosporin commonly used for surgical prophylaxis and IV treatment of more serious infections. Keflex is oral and suitable for outpatient therapy but is not appropriate for severe infections requiring IV therapy.
Cefuroxime (a second‑generation cephalosporin) generally offers broader gram‑negative coverage than Keflex and better activity against certain respiratory pathogens, making cefuroxime a common choice for some community respiratory infections where broader coverage is needed.
Third‑generation oral cephalosporins like cefdinir have broader gram‑negative coverage and sometimes better penetration into tissues. Keflex retains strong gram‑positive activity (staph and strep); choice depends on the suspected pathogen and local resistance patterns.
They can both treat otitis media when the causative organisms are susceptible, but cefaclor (second generation) may have different dosing and side effect profiles. The best choice depends on local resistance patterns, prior antibiotic exposure, and allergy history.
Cefpodoxime (a third‑generation oral cephalosporin) often has improved gram‑negative coverage and may be preferred for some UTIs or resistant respiratory pathogens. Keflex is effective for many uncomplicated UTIs and skin infections caused by susceptible organisms.
Ceftriaxone is a broad‑spectrum, long‑acting third‑generation cephalosporin given IV or IM and is used for serious systemic infections, meningitis, and bloodstream infections. Keflex is oral and intended for milder outpatient infections; they are not interchangeable for severe disease.
Yes; most first‑generation cephalosporins have similar efficacy against common skin pathogens like Staphylococcus aureus (non‑MRSA) and Streptococcus species. Choice often depends on dosing convenience, formulation, and patient factors.
Cross‑reactivity among cephalosporins depends on chemical side‑chain similarities. If you’ve had an allergic reaction to one cephalosporin, discuss specific drug history with your clinician or allergist before taking another; some cephalosporins may be safer than others.
They have overlapping but distinct spectra. For many skin infections and some UTIs, Keflex is an appropriate alternative; for infections where enterococci or certain gram‑negative bacteria are suspected, amoxicillin or another agent may be preferred. Substitution should follow prescriber guidance.
Side effects are broadly similar across oral cephalosporins—GI upset, diarrhea, and allergic reactions are most common. Differences are mostly in frequency and rare adverse events; individual tolerance varies.
Key factors include the suspected or confirmed pathogen and its susceptibility, infection severity, route of administration needed (oral vs IV), patient kidney function, allergy history, dosing convenience, and local resistance patterns. A clinician will weigh these to select the most appropriate agent.