Keflex 125mg/5ml Susp 200ml
It is used to treat bacterial infections.
Drug Class
Antibiotic
Pharmacologic Class
First-generation Cephalosporin
Pregnancy Category
Category B
FDA Approved
Jan 1971
DEA Schedule
Not Controlled
Overview
What is this medicine?
Cephalexin is an antibiotic that belongs to a group of medicines called cephalosporins. It works by killing bacteria that cause infections. It is used to treat various bacterial infections, such as ear infections, skin infections, bone infections, and urinary tract infections.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If it causes stomach upset, take it with food to help minimize this side effect. Continue using the medication even if your symptoms improve.
Before taking a liquid dose, shake the container well. Measure the dose carefully using the measuring device that comes with the medication. If a measuring device is not provided, ask your pharmacist for one to ensure accurate dosing.
Storing and Disposing of Your Medication
Store the medication in the refrigerator to maintain its potency. Discard any unused portion after 2 weeks. Keep the container lid tightly closed to prevent contamination. Store all medications in a safe location, out of the reach of children and pets, to avoid accidental ingestion.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. If it causes stomach upset, take it with food to help minimize this side effect. Continue using the medication even if your symptoms improve.
Before taking a liquid dose, shake the container well. Measure the dose carefully using the measuring device that comes with the medication. If a measuring device is not provided, ask your pharmacist for one to ensure accurate dosing.
Storing and Disposing of Your Medication
Store the medication in the refrigerator to maintain its potency. Discard any unused portion after 2 weeks. Keep the container lid tightly closed to prevent contamination. Store all medications in a safe location, out of the reach of children and pets, to avoid accidental ingestion.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take the medication exactly as prescribed by your doctor, even if you start to feel better. Do not skip doses or stop taking it early, as this can lead to antibiotic resistance.
- Shake the oral suspension well before each use.
- Measure liquid medicine carefully using the provided measuring spoon or cup, not a household spoon.
- Cephalexin can be taken with or without food. If it causes stomach upset, take it with food or milk.
- Stay hydrated by drinking plenty of fluids.
- Avoid alcohol consumption, as it may worsen side effects like stomach upset.
- If you are taking oral contraceptives, discuss with your doctor as some antibiotics may reduce their effectiveness (though this is controversial for cephalexin).
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
250 mg to 500 mg every 6 hours, or 500 mg every 12 hours
Dose Range:
250 - 1000 mg
Condition-Specific Dosing:
mildToModerateInfections:
250 mg every 6 hours or 500 mg every 12 hours
skinAndSoftTissueInfections:
500 mg every 12 hours
streptococcalPharyngitis:
250 mg every 6 hours or 500 mg every 12 hours for at least 10 days
boneInfections:
250 mg to 500 mg every 6 hours
urinaryTractInfections:
250 mg every 6 hours or 500 mg every 12 hours
Pediatric Dosing
Neonatal:
Not established (use caution, consult specific guidelines)
Infant:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours (up to 100 mg/kg/day for severe infections)
Child:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours (up to 100 mg/kg/day for severe infections)
Adolescent:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours (up to 100 mg/kg/day for severe infections), or adult dosing if weight allows
Dose Adjustments
Renal Impairment:
Mild:
CrCl 30-59 mL/min: No dose adjustment typically needed, but consider extending dosing interval to every 8-12 hours for severe infections.
Moderate:
CrCl 15-29 mL/min: 250 mg every 8-12 hours (max 500 mg every 8-12 hours).
Severe:
CrCl < 15 mL/min: 250 mg every 12-24 hours (max 500 mg every 12-24 hours).
Dialysis:
Hemodialysis: 250 mg to 500 mg after each dialysis session. Peritoneal Dialysis: 250 mg every 12 hours.
Hepatic Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Pharmacology
Mechanism of Action
Cephalexin is a bactericidal antibiotic that inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins (PBPs). This inhibits the final transpeptidation step of peptidoglycan synthesis in the bacterial cell wall, leading to cell lysis and death.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 90%
Tmax:
Approximately 1 hour (oral suspension may be slightly faster)
FoodEffect:
Food delays absorption but does not significantly affect the total amount absorbed.
Distribution:
Vd:
Approximately 0.26 L/kg
ProteinBinding:
Approximately 10-15%
CnssPenetration:
Limited (does not achieve therapeutic concentrations in CSF unless meninges are inflamed)
Elimination:
HalfLife:
Approximately 0.5 to 1.2 hours (prolonged in renal impairment)
Clearance:
Primarily renal clearance
ExcretionRoute:
Renal (glomerular filtration and tubular secretion)
Unchanged:
Approximately 70-90%
Pharmacodynamics
OnsetOfAction:
Rapid
PeakEffect:
Within 1 hour of administration
DurationOfAction:
Dependent on dosing interval (typically 6-12 hours based on half-life and MIC)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of a severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), such as:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, or eyes
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Fever, chills, or sore throat
Unexplained bruising or bleeding
Feeling extremely tired or weak
Confusion
Hallucinations (seeing or hearing things that are not there)
Difficulty urinating or changes in urine output
Seizures
Severe dizziness
Severe headache
Severe joint pain
Vaginal itching or discharge
Important Note: Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called C. diff-associated diarrhea (CDAD) may occur. This condition can lead to life-threatening bowel problems. If you experience stomach pain, cramps, or loose, watery, or bloody stools, contact your doctor immediately. Before treating diarrhea, consult with your doctor.
Other Possible Side Effects
Most people taking this medication do not experience severe side effects, and some may not have any side effects at all. However, if you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical attention:
Stomach pain or diarrhea
Upset stomach or vomiting
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult with your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of a severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis), such as:
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, or eyes
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Fever, chills, or sore throat
Unexplained bruising or bleeding
Feeling extremely tired or weak
Confusion
Hallucinations (seeing or hearing things that are not there)
Difficulty urinating or changes in urine output
Seizures
Severe dizziness
Severe headache
Severe joint pain
Vaginal itching or discharge
Important Note: Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called C. diff-associated diarrhea (CDAD) may occur. This condition can lead to life-threatening bowel problems. If you experience stomach pain, cramps, or loose, watery, or bloody stools, contact your doctor immediately. Before treating diarrhea, consult with your doctor.
Other Possible Side Effects
Most people taking this medication do not experience severe side effects, and some may not have any side effects at all. However, if you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical attention:
Stomach pain or diarrhea
Upset stomach or vomiting
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult with your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of an allergic reaction: rash, hives, itching, swelling of the face, lips, tongue, or throat, difficulty breathing or swallowing.
- Severe or watery diarrhea, especially if it contains blood or mucus (may be a sign of Clostridioides difficile-associated diarrhea).
- Unusual bleeding or bruising.
- Yellowing of the skin or eyes (jaundice).
- Dark urine.
- Persistent sore throat or fever (may indicate a new infection or blood disorder).
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
If you are currently taking probenecid, as this may interact with the medication.
Additionally, to ensure safe treatment, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your existing health problems
This information will help your doctor determine whether it is safe for you to take this medication in conjunction with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
If you are currently taking probenecid, as this may interact with the medication.
Additionally, to ensure safe treatment, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your existing health problems
This information will help your doctor determine whether it is safe for you to take this medication in conjunction with your other medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you are taking this drug for an extended period, your doctor may recommend regular blood tests to monitor your condition.
If you have diabetes and regularly test your urine for glucose, consult with your doctor to determine the most suitable testing method for you, as this medication may interfere with certain test results.
Be aware that this drug can affect the outcomes of some laboratory tests. Therefore, it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this medication.
Do not take this medication for longer than prescribed, as this can increase the risk of developing a secondary infection.
If you are pregnant, planning to become pregnant, or are breastfeeding, discuss the potential benefits and risks of this medication with your doctor to make an informed decision about your treatment.
If you have diabetes and regularly test your urine for glucose, consult with your doctor to determine the most suitable testing method for you, as this medication may interfere with certain test results.
Be aware that this drug can affect the outcomes of some laboratory tests. Therefore, it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this medication.
Do not take this medication for longer than prescribed, as this can increase the risk of developing a secondary infection.
If you are pregnant, planning to become pregnant, or are breastfeeding, discuss the potential benefits and risks of this medication with your doctor to make an informed decision about your treatment.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Epigastric distress
- Diarrhea
- Hematuria (blood in urine)
- In rare cases, seizures (especially in patients with renal impairment)
What to Do:
Call 1-800-222-1222 (Poison Control) immediately or seek emergency medical attention. Treatment is primarily supportive; hemodialysis may be useful in severe cases of overdose, especially with renal impairment.
Drug Interactions
Moderate Interactions
- Metformin
- Probenecid
- Oral Contraceptives (potential theoretical interaction)
Monitoring
Baseline Monitoring
Culture and Susceptibility Testing
Rationale: To confirm susceptibility of the causative organism to cephalexin and guide appropriate therapy.
Timing: Prior to initiation of therapy
Renal Function (BUN, Creatinine)
Rationale: To establish baseline renal function, especially in elderly patients or those with pre-existing renal impairment, as cephalexin is primarily renally eliminated.
Timing: Prior to initiation of therapy
Routine Monitoring
Clinical Response (resolution of signs/symptoms of infection)
Frequency: Daily during acute treatment, then as clinically indicated
Target: Improvement or resolution of infection
Action Threshold: Lack of improvement or worsening symptoms may indicate treatment failure, resistance, or superinfection.
Signs of Superinfection (e.g., oral thrush, vaginal candidiasis, severe diarrhea)
Frequency: Daily during treatment and for several weeks post-treatment
Target: Absence of new infections
Action Threshold: Development of new infections requires evaluation and appropriate management (e.g., discontinuation of cephalexin, antifungal/antimicrobial therapy).
Renal Function (BUN, Creatinine)
Frequency: Periodically, especially in patients with pre-existing renal impairment or on prolonged therapy
Target: Within patient's baseline range
Action Threshold: Significant increase may require dose adjustment or discontinuation.
Symptom Monitoring
- Rash
- Hives
- Itching
- Swelling (face, lips, tongue, throat)
- Difficulty breathing or swallowing
- Severe diarrhea (especially if bloody or watery)
- Abdominal pain/cramping
- Fever
- Sore throat
- Unusual bleeding or bruising
- Yellowing of skin or eyes (jaundice)
- Dark urine
- Unusual tiredness or weakness
Special Patient Groups
Pregnancy
Cephalexin is generally considered safe for use during pregnancy (Pregnancy Category B). Animal reproduction studies have not demonstrated a risk to the fetus, and there are no adequate and well-controlled studies in pregnant women. It should be used during pregnancy only if clearly needed.
Trimester-Specific Risks:
First Trimester:
No increased risk of congenital anomalies observed in human studies.
Second Trimester:
Generally considered safe.
Third Trimester:
Generally considered safe.
Lactation
Cephalexin is excreted in small amounts into breast milk. It is generally considered compatible with breastfeeding (Lactation Risk L2 - Safer). Monitor breastfed infant for potential adverse effects such as diarrhea, candidiasis (thrush, diaper rash), or allergic reaction (rash).
Infant Risk:
Low risk of adverse effects; potential for alteration of infant gut flora, leading to diarrhea or candidiasis.
Pediatric Use
Cephalexin is widely used and generally well-tolerated in pediatric patients. Dosing is weight-based. Safety and efficacy have been established for various infections in pediatric patients from infancy through adolescence. Neonatal use requires caution and specific guidelines due to immature renal function.
Geriatric Use
No overall differences in safety or effectiveness have been observed between elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Due to the higher likelihood of decreased renal function in elderly patients, dose adjustment based on creatinine clearance may be necessary.
Clinical Information
Clinical Pearls
- Cephalexin is a first-generation cephalosporin, primarily active against Gram-positive bacteria (e.g., Staphylococcus aureus, Streptococcus pyogenes) and some Gram-negative bacteria (e.g., E. coli, Klebsiella pneumoniae, Proteus mirabilis).
- It is a common choice for skin and soft tissue infections, streptococcal pharyngitis, and uncomplicated urinary tract infections.
- The oral suspension should be stored in the refrigerator and discarded after 14 days.
- Patients should be advised to complete the full course of therapy to prevent the development of antibiotic resistance.
- Cross-reactivity with penicillins is low (approximately 1-5%), but caution is advised in patients with a history of severe penicillin allergy.
Alternative Therapies
- Amoxicillin
- Dicloxacillin
- Clindamycin
- Macrolides (e.g., Azithromycin, Clarithromycin) for specific indications
- Other cephalosporins (e.g., Cefadroxil, Cefazolin)
Cost & Coverage
Average Cost:
Not available Not available
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe and effective treatment, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it is a good idea to consult with your pharmacist. If you have any questions or concerns about this medication, do not hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When reporting the incident, be prepared to provide details about the medication taken, the amount, and the time it occurred.