Cephalexin 125mg/5ml Susp 100ml
It is used to treat bacterial infections.
Drug Class
Antibiotic
Pharmacologic Class
First-generation Cephalosporin
Pregnancy Category
B
FDA Approved
Jan 1971
DEA Schedule
Not Controlled
Overview
What is this medicine?
Cephalexin is an antibiotic medication used to treat various bacterial infections, such as ear infections, skin infections, and urinary tract infections. It works by killing the bacteria that cause these 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 you experience stomach upset, taking it with food may help. Continue using the medication even if your symptoms improve.
Before taking a dose, shake the liquid medication well. Measure liquid doses carefully using the measuring device that comes with the medication. If one is not provided, ask your pharmacist for a suitable device to measure your doses.
Storing and Disposing of Your Medication
Store your medication in the refrigerator and discard any unused portion after 2 weeks. Keep the lid tightly closed and store all medications in a safe place, 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 dose.
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 you experience stomach upset, taking it with food may help. Continue using the medication even if your symptoms improve.
Before taking a dose, shake the liquid medication well. Measure liquid doses carefully using the measuring device that comes with the medication. If one is not provided, ask your pharmacist for a suitable device to measure your doses.
Storing and Disposing of Your Medication
Store your medication in the refrigerator and discard any unused portion after 2 weeks. Keep the lid tightly closed and store all medications in a safe place, 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 dose.
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 the infection returning or becoming harder to treat.
- 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, try taking it with food or milk.
- Drink plenty of fluids to help prevent kidney stones, though this is a rare side effect.
- Avoid alcohol while taking antibiotics, as it can worsen side effects like stomach upset.
Available Forms & Alternatives
Available Strengths:
- Cephalexin 250mg/5ml Susp 100ml
- Cephalexin 250mg/5ml Susp 200ml
- Cephalexin 125mg/5ml Susp 100ml
- Cephalexin 125mg/5ml Susp 200ml
- Cephalexin 250mg Capsules
- Cephalexin 500mg Capsules
- Cephalexin 250mg Tablets
- Cephalexin 500mg Tablets
- Cephalexin 750mg Capsules
- Cephalexin 125mg/5ml Susp 100ml
- Cephalexin 500mg Tablets
- Cephalexin 250mg Tablets
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
severeInfections:
500 mg to 1000 mg every 6 hours
skinAndSoftTissueInfections:
500 mg every 12 hours
streptococcalPharyngitis:
250 mg every 6 hours or 500 mg every 12 hours for at least 10 days
urinaryTractInfections:
250 mg every 6 hours or 500 mg every 12 hours
Pediatric Dosing
Neonatal:
Not established (use with caution, consult specialist)
Infant:
25 to 50 mg/kg/day in divided doses (every 6 or 8 hours). For severe infections, up to 100 mg/kg/day.
Child:
25 to 50 mg/kg/day in divided doses (every 6 or 8 hours). For severe infections, up to 100 mg/kg/day. Max 4 g/day.
Adolescent:
Same as adult dosing (250 mg to 500 mg every 6 hours, or 500 mg every 12 hours)
Dose Adjustments
Renal Impairment:
Mild:
CrCl 30-59 mL/min: No adjustment needed for standard doses, consider extending interval to q8-12h for higher doses.
Moderate:
CrCl 10-29 mL/min: 250 mg to 500 mg every 12 hours.
Severe:
CrCl <10 mL/min: 250 mg to 500 mg every 12 to 24 hours.
Dialysis:
Hemodialysis: Administer a supplemental dose of 250-500 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. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, thereby inhibiting the transpeptidation stage 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 the rate of absorption (Tmax) but does not significantly affect the extent of absorption (AUC).
Distribution:
Vd:
Approximately 0.26 L/kg
ProteinBinding:
Approximately 10-15%
CnssPenetration:
Limited (does not achieve therapeutically effective concentrations in CSF unless meninges are inflamed)
Elimination:
HalfLife:
Approximately 0.5 to 1.2 hours (in individuals with normal renal function)
Clearance:
Primarily renal clearance via glomerular filtration and tubular secretion.
ExcretionRoute:
Renal (urine)
Unchanged:
Approximately 70-90% of the dose is excreted unchanged in the urine within 8 hours.
Pharmacodynamics
OnsetOfAction:
Rapid (within 1 hour)
PeakEffect:
Approximately 1 hour after oral administration
DurationOfAction:
Approximately 6-8 hours (based on dosing interval)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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
Diarrhea, especially if it is severe, bloody, or accompanied by stomach pain or cramps (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Common Side Effects
Most people experience few or no side effects when 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 experience any side effects, you can report them to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor is also available to provide guidance and support regarding side effects.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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
Diarrhea, especially if it is severe, bloody, or accompanied by stomach pain or cramps (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Common Side Effects
Most people experience few or no side effects when 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 experience any side effects, you can report them to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor is also available to provide guidance and support regarding side effects.
Seek Immediate Medical Attention If You Experience:
- Severe or watery diarrhea, especially if it contains blood or mucus (may be a sign of C. difficile infection)
- New or worsening rash, hives, or itching
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
- Severe stomach pain or cramps
- Unusual bruising or bleeding
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Fever or sore throat that doesn't improve
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 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 second 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 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 second 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 suspected overdose, seek immediate medical attention. Call 911 or your local poison control center (e.g., 1-800-222-1222 in the US). Treatment is generally supportive, including gastric lavage or activated charcoal if ingestion was recent. Hemodialysis may be useful in severe cases.
Drug Interactions
Major Interactions
- Metformin (increased metformin levels, risk of lactic acidosis)
- Probenecid (decreased renal excretion of cephalexin, increased cephalexin levels)
Moderate Interactions
- Oral Contraceptives (potential for reduced efficacy, though evidence is weak for most antibiotics)
- Warfarin (potential for enhanced anticoagulant effect, monitor INR)
- Live Bacterial Vaccines (e.g., Typhoid vaccine - may reduce efficacy of vaccine)
Monitoring
Baseline Monitoring
Renal function (CrCl, BUN, Creatinine)
Rationale: Cephalexin is primarily renally eliminated; dose adjustment is necessary in renal impairment.
Timing: Prior to initiation, especially in elderly or patients with known renal issues.
Allergy history (especially to penicillins or other cephalosporins)
Rationale: Risk of cross-reactivity.
Timing: Prior to initiation.
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.
Gastrointestinal symptoms (diarrhea, nausea, vomiting)
Frequency: Daily
Target: Absence or mild, tolerable symptoms
Action Threshold: Severe or persistent diarrhea (especially bloody) may indicate C. difficile infection; discontinue and investigate.
Skin rash or allergic reactions
Frequency: Daily
Target: Absence of rash, itching, swelling
Action Threshold: Development of rash, urticaria, or signs of anaphylaxis requires immediate discontinuation.
INR (if on warfarin)
Frequency: As clinically indicated, especially at initiation or dose change
Target: Therapeutic range for patient's condition
Action Threshold: Significant deviation from target range; adjust warfarin dose as needed.
Symptom Monitoring
- Fever
- Pain
- Inflammation
- Redness
- Swelling
- Pus/discharge
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Skin rash
- Itching
- Hives
- 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:
Low risk, no evidence of teratogenicity.
Second Trimester:
Low risk.
Third Trimester:
Low risk.
Lactation
Cephalexin is excreted in small amounts into breast milk. It is generally considered compatible with breastfeeding (Lactation Risk L2). Monitor breastfed infants for potential adverse effects such as diarrhea, candidiasis (thrush, diaper rash), or allergic reactions (rash).
Infant Risk:
Low risk.
Pediatric Use
Cephalexin is widely used and generally well-tolerated in pediatric patients. Dosing is weight-based. Neonatal use should be approached with caution and under specialist guidance due to immature renal function.
Geriatric Use
Elderly patients may have reduced renal function, which can lead to higher plasma concentrations of cephalexin. Dose adjustment based on creatinine clearance is recommended in elderly patients with impaired renal function. Otherwise, no specific dose adjustment is needed.
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 a common choice for skin and soft tissue infections (e.g., cellulitis, impetigo), uncomplicated urinary tract infections, and streptococcal pharyngitis.
- Cephalexin is NOT effective against MRSA (Methicillin-Resistant Staphylococcus aureus) or most anaerobic bacteria.
- Complete the full course of therapy, even if symptoms improve, to prevent resistance and recurrence.
- Oral suspension should be refrigerated after reconstitution and discarded after 14 days.
Alternative Therapies
- Other first-generation cephalosporins (e.g., Cefazolin - IV)
- Penicillins (e.g., Amoxicillin, Dicloxacillin - depending on susceptibility)
- Macrolides (e.g., Azithromycin, Clarithromycin - for penicillin-allergic patients, different spectrum)
- Fluoroquinolones (e.g., Ciprofloxacin, Levofloxacin - broader spectrum, reserved for specific infections)
- Trimethoprim/Sulfamethoxazole (for UTIs, skin infections, different spectrum)
- Clindamycin (for skin/soft tissue infections, anaerobic coverage)
Cost & Coverage
Average Cost:
Varies, typically low per 100ml of 125mg/5ml suspension
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Preferred Generic) or Tier 2 (Non-Preferred Generic) on most insurance formularies.
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. 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 be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.