Keflex 250mg/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 many different types of bacterial infections, such as ear infections, skin 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 device is not provided, ask your pharmacist for one to ensure accurate measurement.
Storing and Disposing of Your Medication
Store the medication in the refrigerator to maintain its effectiveness. Discard any unused portion after 2 weeks. Keep the lid tightly closed and store all medications in a safe location, out of the reach of children and pets.
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 a 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 device is not provided, ask your pharmacist for one to ensure accurate measurement.
Storing and Disposing of Your Medication
Store the medication in the refrigerator to maintain its effectiveness. Discard any unused portion after 2 weeks. Keep the lid tightly closed and store all medications in a safe location, out of the reach of children and pets.
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 a missed one.
Lifestyle & Tips
- Take the medication exactly as prescribed by your doctor. Do not skip doses or stop taking it early, even if you feel better, as this can lead to antibiotic resistance.
- Shake the suspension well before each use.
- Measure the 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.
- Store the suspension in the refrigerator and discard any unused portion after 14 days.
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:
mild_moderate_infections:
250 mg every 6 hours or 500 mg every 12 hours
severe_infections:
500 mg to 1 g every 6 hours (maximum 4 g/day)
Pediatric Dosing
Neonatal:
Not established (use with caution, consult specific guidelines)
Infant:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours
Child:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours (up to 100 mg/kg/day for severe infections, max 4 g/day)
Adolescent:
25 to 50 mg/kg/day in divided doses every 6 or 8 hours (up to 100 mg/kg/day for severe infections, max 4 g/day, or adult dosing if weight appropriate)
Dose Adjustments
Renal Impairment:
Mild:
CrCl 30-59 mL/min: No specific adjustment needed for standard doses, but monitor.
Moderate:
CrCl 15-29 mL/min: 250 mg every 8-12 hours or 500 mg every 12 hours.
Severe:
CrCl < 15 mL/min: 250 mg every 12-24 hours or 500 mg every 24 hours.
Dialysis:
Hemodialysis: 250 mg to 500 mg after each dialysis session. Peritoneal Dialysis: 250 mg every 12 hours or 500 mg every 24 hours.
Confidence:
High
Hepatic Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed
Pharmacology
Mechanism of Action
Cephalexin is a first-generation cephalosporin antibiotic. It exerts its bactericidal action by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, thereby inhibiting the transpeptidation step of peptidoglycan synthesis. This leads to the disruption of the cell wall, resulting in bacterial cell lysis and death.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 90%
Tmax:
Approximately 1 hour (fasted state)
FoodEffect:
Food may delay 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 therapeutically effective concentrations in CSF)
Elimination:
HalfLife:
Approximately 0.5 to 1.2 hours (normal renal function)
Clearance:
Primarily renal clearance
ExcretionRoute:
Renal (glomerular filtration and tubular secretion)
Unchanged:
Approximately 70-90% excreted unchanged in urine within 8 hours
Pharmacodynamics
OnsetOfAction:
Rapid
PeakEffect:
Within 1 hour of administration
DurationOfAction:
Approximately 6-8 hours (based on dosing frequency)
Confidence:
Medium
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 immediately or seek emergency medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty 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
+ Fatigue
+ 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
Diarrhea, especially if it is severe, bloody, or accompanied by stomach pain or cramps (a rare but potentially life-threatening condition called C. diff-associated diarrhea, or CDAD, may occur)
Common Side Effects
Most people experience few or no side effects while taking this medication. However, some common side effects may occur, including:
Stomach pain or diarrhea
Upset stomach or vomiting
If any of these side effects or any other symptoms bother you or do not go away, contact your doctor for advice.
Reporting Side Effects
If you have questions or concerns about side effects, you can:
Contact your doctor for medical advice
Report side effects to the FDA at 1-800-332-1088
Submit a report 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 immediately or seek emergency medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty 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
+ Fatigue
+ 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
Diarrhea, especially if it is severe, bloody, or accompanied by stomach pain or cramps (a rare but potentially life-threatening condition called C. diff-associated diarrhea, or CDAD, may occur)
Common Side Effects
Most people experience few or no side effects while taking this medication. However, some common side effects may occur, including:
Stomach pain or diarrhea
Upset stomach or vomiting
If any of these side effects or any other symptoms bother you or do not go away, contact your doctor for advice.
Reporting Side Effects
If you have questions or concerns about side effects, you can:
Contact your doctor for medical advice
Report side effects to the FDA at 1-800-332-1088
Submit a report online at https://www.fda.gov/medwatch
Seek Immediate Medical Attention If You Experience:
- Severe diarrhea (watery or bloody stools), especially if accompanied by fever or stomach cramps (could be C. difficile infection)
- New or worsening rash, hives, or itching
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
- Unusual bruising or bleeding
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Signs of a new infection (e.g., fever, sore throat, chills) that may indicate a superinfection
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.
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 if it is safe for you to take this medication with your other drugs and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor to confirm 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.
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 if it is safe for you to take this medication with your other drugs and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor to confirm 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. Additionally, be sure to notify all your healthcare providers and laboratory personnel that you are taking this medication, as it may affect the accuracy of certain lab tests.
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, it is crucial to discuss the potential benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
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. Additionally, be sure to notify all your healthcare providers and laboratory personnel that you are taking this medication, as it may affect the accuracy of certain lab tests.
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, it is crucial to discuss the potential benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Epigastric distress
- Diarrhea
- Hematuria (blood in urine)
- Renal dysfunction (rare)
- Convulsions (rare)
What to Do:
In case of overdose, seek immediate medical attention or call a Poison Control Center (1-800-222-1222). Treatment is primarily supportive. Gastric lavage may be indicated if performed within 1 hour of ingestion. Hemodialysis may be useful in accelerating the removal of cephalexin from the blood, especially in patients with renal impairment.
Drug Interactions
Major Interactions
- Metformin (increased metformin levels, monitor for lactic acidosis)
- Probenecid (decreased renal excretion of cephalexin, leading to increased and prolonged cephalexin plasma concentrations)
Moderate Interactions
- Warfarin (potential for increased INR, monitor coagulation parameters)
- Live bacterial vaccines (e.g., typhoid vaccine - may reduce efficacy of vaccine)
- Oral contraceptives (theoretical risk of reduced efficacy, though not consistently proven)
Monitoring
Baseline Monitoring
Renal function (BUN, creatinine)
Rationale: To establish baseline for dose adjustment in renal impairment and for prolonged therapy.
Timing: Prior to initiation of therapy, especially in patients with known or suspected renal impairment.
Routine Monitoring
Signs and symptoms of infection resolution
Frequency: Daily
Target: Improvement in fever, pain, inflammation
Action Threshold: Lack of improvement or worsening symptoms after 2-3 days may indicate treatment failure or resistant organism.
Signs and symptoms of adverse reactions (e.g., diarrhea, rash)
Frequency: Daily
Target: Absence of severe adverse effects
Action Threshold: Development of severe diarrhea (especially C. difficile-associated diarrhea), widespread rash, or signs of allergic reaction requires immediate evaluation and discontinuation.
Renal function (BUN, creatinine)
Frequency: Periodically, especially during prolonged therapy or in patients with pre-existing renal impairment
Target: Within normal limits or stable
Action Threshold: Significant increase in BUN/creatinine may necessitate dose adjustment or discontinuation.
Symptom Monitoring
- Fever
- Pain
- Redness
- Swelling
- Pus/discharge
- Diarrhea (especially severe or bloody)
- Rash
- Itching
- Difficulty breathing
- Swelling of face/throat
Special Patient Groups
Pregnancy
Cephalexin is generally considered safe for use during pregnancy (Pregnancy Category B). Animal reproduction studies have not shown 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 malformations observed.
Second Trimester:
No specific risks identified.
Third Trimester:
No specific risks identified.
Lactation
Cephalexin is excreted in small amounts into breast milk. It is generally considered compatible with breastfeeding (Lactation Risk L2 - Safer). Monitor breastfed infants for potential adverse effects such as diarrhea, candidiasis (thrush, diaper rash), or allergic reactions (rash).
Infant Risk:
Low risk of adverse effects. Potential for alteration of infant gut flora, leading to diarrhea or candidiasis.
Pediatric Use
Dosing is weight-based. Generally well-tolerated in pediatric patients. Close monitoring for adverse effects, especially gastrointestinal disturbances and allergic reactions, is recommended. Ensure accurate measurement of liquid formulations.
Geriatric Use
No specific dose adjustment is needed based on age alone. However, elderly patients are more likely to have decreased renal function, which may require dose adjustment based on creatinine clearance. Monitor renal function closely in this population.
Clinical Information
Clinical Pearls
- Cephalexin is a first-generation cephalosporin, effective against many Gram-positive bacteria (e.g., Staphylococcus aureus, Streptococcus pyogenes) and some Gram-negative bacteria (e.g., E. coli, Klebsiella pneumoniae, Proteus mirabilis).
- It is commonly used for skin and soft tissue infections, urinary tract infections, and respiratory tract infections (e.g., pharyngitis, tonsillitis).
- Not effective against MRSA (Methicillin-resistant Staphylococcus aureus) or Pseudomonas aeruginosa.
- Patients with a history of severe hypersensitivity (e.g., anaphylaxis) to penicillin should generally avoid cephalexin due to potential cross-reactivity, although the risk is low (1-10%).
- Complete the full course of therapy to prevent the development of antibiotic resistance.
- Oral suspension should be refrigerated and discarded after 14 days.
Alternative Therapies
- Other first-generation cephalosporins (e.g., Cefazolin - IV)
- Penicillins (e.g., Amoxicillin, Dicloxacillin - if susceptible)
- Macrolides (e.g., Azithromycin, Clarithromycin - for penicillin-allergic patients, depending on susceptibility)
- Clindamycin (for skin/soft tissue infections, including some MRSA strains, but different spectrum)
- Trimethoprim/Sulfamethoxazole (for UTIs, some skin infections)
Cost & Coverage
Average Cost:
Varies widely by pharmacy and formulation per 200ml suspension
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't 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 seeking help, be prepared to provide detailed information about the overdose, including the substance taken, the amount, and the time it occurred.