Cephalexin

Introduction

Cephalexin is an antibiotic drug belonging to the cephalosporin class. It is used to treat bacterial infections caused by susceptible Gram-positive bacteria, including skin, respiratory, urinary tract, and bone infections. It is also often prescribed as an off-label remedy for UTI infections, acne, impetigo, and gum diseases.

Uses for

Cephalexin is primarily used in the treatment of infections caused by Gram-positive bacteria, such as streptococci and staphylococci. Some off-label uses for cephalexin include treatment of impetigo, gum diseases, and urinary tract infections.

Brand Name	Cephalexin
Type
Weight
Generic	Cephalexin
Manufacturer
Available in	English বাংলা

Mechanism of Action

Cephalexin works by inhibiting the synthesis of peptidoglycan, which is an essential component of the bacterial cell wall. This action makes the cell wall weak and susceptible to destruction, leading to death of the bacterial cells.

How Long Does It Take To Work?

Cephalexin starts to work within 1 to 2 hours of taking the medicine. Symptoms of an infection should start to improve within a few days of taking the medication.

Absorption

Cephalexin is rapidly and completely absorbed following oral administration.

Route of Elimination

Cephalexin is eliminated through the kidneys by glomerular filtration and tubular secretion.

Dosage Information

Cephalexin is available in oral tablets and capsules in dosages of 250, 500, and 750 mg. For skin, bone, and urinary tract infections, the usual dose is 250-500mg twice daily or 500-750mg once daily. For respiratory infections, the usual dose is 250-500mg every 6-8 hours or 500-750mg every 12 hours.

Administration

Cephalexin should be taken with food and plenty of fluids to help prevent irritation of the stomach and intestines. If you miss a dose, take it as soon as you remember unless it is close to the time of your next dose. In that case, skip the missed dose and continue with your regular dosing schedule.

Side Effects

Common side effects of Cephalexin include nausea, vomiting, and diarrhea. Other side effects include rash, dizziness, headache, and abdominal pain. In rare cases, Cephalexin may also cause allergic reactions or liver damage. Call your doctor right away if you experience any unusual or severe symptoms.

Toxicity

Cephalexin is considered to be safe and well-tolerated. However, an overdose may lead to nausea, vomiting, and diarrhea. Severe overdose may result in liver damage, kidney damage, and coma.

Precaution

Patients with kidney and/or liver disease, asthma, and pregnant or breastfeeding women should take Cephalexin with caution, as they are more susceptible to its side effects. As the drug may interact with other medications, it is important to inform your physician if you are on any other medication, including over the counter drugs.

Interaction

Cephalexin may interact with other drugs and should not be administered with drugs that reduce the activity of bacteria, such as tetracyclines and macrolide antibiotics.

Disease Interaction

Cephalexin may interact with certain chronic diseases, such as kidney and liver disease. Patients with kidney or liver disease should take the medication with caution and under medical supervision.

Drug Interaction

Cephalexin may interact with other drugs, such as penicillin, tetracyclines, and macrolide antibiotics. It may also interact with drugs that reduce the activity of bacteria, such as chloramphenicol, probenecid, and allopurinol. It is important to inform your physician if you are taking any other medication before taking cephalexin.

Food Interactions

Cephalexin may interact with food and beverages. Taking it with food may decrease its effectiveness. It should not be taken with alcohol.

Pregnancy Use

Pregnant women should take cephalexin with caution and only after consulting their physician. This drug can be used during pregnancy if deemed necessary by the physician.

Lactation Use

Cephalexin should be used with caution in lactating women. It should not be used during the first trimester of pregnancy.

Acute Overdose

An overdose of cephalexin may lead to nausea, vomiting, and diarrhea. Severe overdoses may cause liver damage, kidney damage, and even coma in rare cases. Seek medical attention right away if you suspect an overdose.

Contraindication

Cephalexin should not be used in patients with known hypersensitivity or allergy to cephalosporins. It should also not be used in patients with kidney and liver disease.

Use Direction

Cephalexin should be used as directed by a physician. Take it with food and plenty of fluids to help prevent stomach irritation. Do not skip doses or stop taking the drug even if symptoms improve.

Storage Condition

Cephalexin should be stored at room temperature, away from heat and moisture. Keep all medicines out of reach of children.

Volume of Distribution

Cephalexin has a volume of distribution of 0.14-0.25 L/kg.

Half Life

The half life of cephalexin is 0.9-1.2 hours.

Clearance

The clearance of cephalexin is 0.07-0.55 L/h/kg.

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Some Frequently Asked Questions About Cephalexin

1. What is Cephalexin ?

Cephalexin is an oral antibiotic in the cephalosporin class, specifically a first-generation cephalosporin. It is used to treat a variety of bacterial infections by interfering with the bacteria’s cell wall synthesis, leading to their death. It’s available under brand names like Keflex or as a generic in capsules, tablets, or liquid suspension.

2. What class of drug is Cephalexin ?

Cephalexin belongs to the cephalosporin class of antibiotics, which are beta-lactam antibiotics similar to penicillins. As a first-generation cephalosporin, it’s particularly effective against gram-positive bacteria and some gram-negative bacteria.

3. How does Cephalexin work?

Cephalexin works by binding to penicillin-binding proteins (PBPs) in bacterial cell walls, inhibiting the final step of peptidoglycan synthesis. This weakens the cell wall, causing the bacteria to burst due to osmotic pressure. It’s bactericidal, meaning it kills bacteria rather than just stopping their growth.

4. What conditions does Cephalexin treat?

It treats infections caused by susceptible bacteria, including:

• Skin infections: E.g., cellulitis, impetigo.
• Respiratory tract infections: E.g., streptococcal pharyngitis (strep throat).
• Urinary tract infections (UTIs): E.g., cystitis.
• Bone infections: E.g., osteomyelitis.
• Ear infections: E.g., otitis media.

It’s not effective against viral infections.

5. Is Cephalexin used for anything other than infections?

Its primary use is for bacterial infections. It’s occasionally used prophylactically (e.g., before dental procedures in patients with heart conditions to prevent endocarditis), but this is less common and depends on medical guidelines.

6. How is Cephalexin taken?

Cephalexin is taken orally as capsules, tablets, or a liquid suspension. It’s usually taken every 6–12 hours (2–4 times daily) with or without food, though food may reduce stomach upset. The liquid form should be shaken well before use.

7. What is the typical dosage for adults?

For adults, the usual dose is 250–500 mg every 6 hours or 500 mg every 12 hours, depending on the infection’s severity. For severe infections, up to 4 grams daily may be prescribed, split into doses. Treatment typically lasts 7–14 days.

8. What is the dosage for children?

For children, the dose is based on weight, typically 25–50 mg/kg/day, divided into 2–4 doses. For example, a 20 kg child might take 500–1000 mg daily. Higher doses (up to 100 mg/kg/day) may be used for severe infections, under medical supervision.

9. Can Cephalexin be taken with food?

Yes, it can be taken with or without food. Taking it with food may reduce stomach irritation, though it slightly slows absorption without affecting overall effectiveness.

10. What should I do if I miss a dose?

If you miss a dose, take it as soon as you remember unless it’s nearly time for the next dose. In that case, skip the missed dose and continue the schedule. Don’t double up, as this increases side effect risks.

11. How quickly does Cephalexin work?

Cephalexin starts killing bacteria within hours, but symptom relief may take 1–2 days. Full resolution depends on the infection type and severity, often requiring the full course (7–14 days) to prevent recurrence.

12. What are the common side effects?

Common side effects include:

• Diarrhea: Due to gut flora disruption.
• Nausea: Mild stomach upset.
• Vomiting: Less common but possible.
• Rash: Mild skin reactions.

These are usually temporary and mild.

13. What are the serious side effects?

Rare but serious side effects include:

• Allergic reactions: Rash, swelling, or difficulty breathing.
• Clostridium difficile colitis: Severe diarrhea from gut overgrowth.
• Liver issues: Yellowing skin (jaundice).
• Kidney problems: Reduced urine output.

Seek immediate medical help if these occur.

14. Why does Cephalexin cause diarrhea?

It disrupts normal gut bacteria, allowing overgrowth of harmful bacteria like *Clostridium difficile*. This can lead to loose stools or, rarely, severe colitis. Probiotics may help, but consult a doctor if diarrhea persists.

15. Can Cephalexin cause allergic reactions?

Yes, especially in those allergic to cephalosporins or penicillins (due to cross-reactivity). Symptoms include rash, itching, or anaphylaxis (rare). Stop use and seek help if severe reactions occur.

16. Who should not take Cephalexin ?

It’s contraindicated for:

• People allergic to cephalosporins: Or with penicillin allergy history (10% cross-reactivity risk).
• Severe kidney disease: Without dose adjustment.

Caution is needed in these cases.

17. Is Cephalexin safe during pregnancy?

Yes, it’s classified as Category B by the FDA, meaning no evidence of fetal harm in animal studies. It’s often used in pregnancy for UTIs, but only under medical supervision.

18. Can I take Cephalexin while breastfeeding?

Yes, it passes into breast milk in small amounts but is generally safe. Monitor the infant for diarrhea or rash, and consult a doctor if concerned.

19. Does Cephalexin interact with other medications?

Yes, it may interact with:

• Probenecid: Increases Cephalexin blood levels.
• Metformin: May increase metformin levels.
• Warfarin: Rarely enhances bleeding risk.

Inform your doctor of all medications.

20. Can I drink alcohol while taking Cephalexin ?

Alcohol doesn’t directly interact with Cephalexin , but it may worsen side effects like nausea or delay healing. Moderate drinking is usually fine, but avoid excess.

21. Does Cephalexin cause weight gain?

No, it doesn’t affect metabolism or cause weight gain. Any weight change might relate to illness or recovery.

22. Can Cephalexin be taken at night?

Yes, it can be taken at any time, as long as doses are evenly spaced (e.g., every 6 6 or 12 hours). Nighttime dosing is fine if it fits your schedule.

23. How long do I need to take Cephalexin ?

Complete the full course (usually 7–14 days), even if symptoms improve, to prevent bacterial resistance or recurrence. Stopping early can worsen the infection.

24. Can Cephalexin be stopped suddenly?

Don’t stop early unless advised by a doctor, as it may lead to incomplete treatment. There’s no withdrawal risk, but the infection could return.

25. Does Cephalexin affect blood sugar?

No, it doesn’t directly affect blood sugar. Any changes would be unrelated to the drug.

26. Can Cephalexin cause yeast infections?

Yes, by disrupting normal flora, it can increase the risk of vaginal yeast infections or oral thrush, especially in women or those with diabetes.

27. What should I avoid while taking Cephalexin ?

Avoid skipping doses and unnecessary antibiotics to prevent resistance. No specific food or activity restrictions apply.

28. Can Cephalexin cause fatigue?

Fatigue isn’t a common side effect. If it occurs, it’s likely from the infection, not the drug.

29. Is Cephalexin safe for elderly patients?

Yes, but dose adjustments may be needed for reduced kidney function, common in older adults. Monitoring is key.

30. Does Cephalexin affect the liver?

Rarely, it may cause mild liver enzyme elevations, but significant liver damage is uncommon unless pre-existing liver disease exists.

31. Can Cephalexin be used in children?

Yes, it’s safe for children with weight-based dosing (25–100 mg/kg/day). It’s commonly used for ear or skin infections.

32. What’s the maximum dose of Cephalexin ?

The maximum is 4 grams daily for adults, split into doses, though this is rare and reserved for severe infections.

33. Can Cephalexin cause dizziness?

Dizziness is rare and not a typical side effect. If it occurs, it might relate to dehydration or the infection.

34. How is Cephalexin different from other antibiotics?

Compared to penicillins, it’s broader-spectrum but less effective against some gram-negative bacteria than later cephalosporins. It’s oral and well-tolerated.

35. Can Cephalexin prevent infections?

It’s not typically used preventatively except in specific cases (e.g., endocarditis prophylaxis). It’s mainly for active infections.

36. Does Cephalexin affect cholesterol?

No, it has no impact on cholesterol levels.

37. Can Cephalexin be taken with other antibiotics?

Rarely, it’s combined with others for complex infections, but this is doctor-directed. Usually, it’s used alone.

38. What tests should I get while on Cephalexin ?

For long-term or high-dose use, check kidney function and liver enzymes. Routine monitoring isn’t needed for short courses.

39. Can Cephalexin cause depression?

No, it doesn’t affect mood or the brain. Depression would be unrelated.

40. Is Cephalexin addictive?

No, it’s not addictive or habit-forming.

41. Can Cephalexin be crushed?

Capsules shouldn’t be crushed, but tablets can be if needed (check with a pharmacist). Liquid forms are available.

42. Does Cephalexin cause hair loss?

No, hair loss isn’t a side effect. Any loss would be from another cause.

43. Can Cephalexin be used for acne?

It’s not a first-line acne treatment but may be used for severe bacterial skin infections contributing to acne.

44. What’s the half-life of Cephalexin ?

Its half-life is about 1 hour in healthy adults, longer with kidney impairment, requiring dose adjustments.

45. Can Cephalexin cause a rash?

Yes, a mild rash is possible, especially with sensitivity. A severe rash may signal an allergy—stop use and seek help.

46. Does Cephalexin affect exercise?

No direct effect, but if you’re unwell, exercise may feel harder. Side effects like diarrhea could also impact activity.

47. Can Cephalexin be taken with aspirin?

Yes, there’s no significant interaction. It’s safe to combine if needed.

48. Is Cephalexin expensive?

No, as a generic, it’s affordable, often costing $10–$20 for a course, depending on dose and region.

49. Can Cephalexin cause stomach pain?

Yes, mild stomach pain or nausea can occur, especially if taken on an empty stomach. Food may help.

50. How should Cephalexin be stored?

Store at room temperature (15–30°C or 59–86°F), away from moisture and heat. Keep liquid forms refrigerated if specified.