Cephalexin, commonly known by its brand names Keflex, Keflet, and Keftab, is a widely used antibiotic belonging to the cephalosporin class. It is a first-generation cephalosporin, which means it is effective against a broad range of bacterial infections. This guide provides an in-depth look at cephalexin, covering its history, mechanism of action, uses, dosage forms, side effects, precautions, drug interactions, and more. By the end of this guide, you will have a thorough understanding of cephalexin and how to use it safely and effectively.
History of Cephalexin
Cephalexin was first discovered in the 1960s as part of the cephalosporin class of antibiotics. The cephalosporins were derived from the fungus Cephalosporium acremonium, which was initially isolated from sewage water in Sardinia, Italy, in 1948. Scientists discovered that this fungus produced natural compounds with antibacterial properties. Over the next two decades, researchers modified these compounds to create more effective and stable antibiotics, leading to the development of cephalexin.
Cephalexin was introduced to the market in the late 1960s.
It quickly became a popular choice for treating bacterial infections due to its broad-spectrum activity and relatively low risk of side effects.
It was one of the first oral cephalosporins, making it more convenient for patients than injectable antibiotics.
Evolution of Use
Since its introduction, cephalexin has remained a cornerstone in treating bacterial infections. Over the years, its use has expanded to include a wide range of infections, from respiratory and skin infections to urinary tract infections (UTIs) and bone infections. Despite the emergence of newer antibiotics, cephalexin continues to be widely prescribed due to its effectiveness, safety profile, and affordability.
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What Is Cephalexin Used For?
Cephalexin is an antibiotic used to treat infections caused by susceptible bacteria. It is effective against both Gram-positive and some Gram-negative bacteria. Below is a detailed list of the conditions cephalexin is commonly used to treat:
1. Respiratory Tract Infections
Cephalexin is often prescribed for infections of the respiratory system, including:
- Bronchitis: Inflammation of the bronchial tubes, often caused by bacterial infections.
- Pneumonia: Infection of the lungs, which can be caused by bacteria such as Streptococcus pneumoniae.
2. Skin and Soft Tissue Infections
Cephalexin is effective against skin infections caused by bacteria, such as:
- Cellulitis: A bacterial infection of the skin and underlying tissues.
- Impetigo: A highly contagious skin infection that often affects children.
- Wound Infections: Infections that occur after surgery or injury.
3. Ear Infections
Cephalexin is commonly used to treat otitis media, an infection of the middle ear that is particularly common in children.
4. Bone Infections
Cephalexin can be used to treat osteomyelitis, an infection of the bone that can occur after an injury or surgery.
5. Urinary Tract Infections (UTIs)
Cephalexin is frequently prescribed for UTIs, including:
- Cystitis: Infection of the bladder.
- Pyelonephritis: Infection of the kidneys.
6. Prostate Infections
Cephalexin may be used to treat prostatitis, an infection of the prostate gland.
Off-Label Uses
Cephalexin may sometimes be prescribed for conditions not officially approved by regulatory agencies. These include:
- Dental Infections: Such as abscesses or gum infections.
- Lyme Disease: Cephalexin may be used as an alternative to other antibiotics in the early stages.
How Does Cephalexin Work?
Cephalexin belongs to the beta-lactam class of antibiotics, which also includes penicillins. It works by inhibiting the bacterial cell wall synthesis, a critical component for bacterial survival. Here’s how it works in detail:
- Cell Wall Disruption: Bacteria rely on their cell walls to maintain their shape and protect themselves from their environment. Cephalexin interferes with the enzymes responsible for building and maintaining the cell wall.
- Bacterial Death: Without a functional cell wall, bacteria cannot maintain their structural integrity. They absorb water, swell, and eventually burst, leading to their death.
Cephalexin is particularly effective against Gram-positive bacteria, such as Staphylococcus aureus and Streptococcus pneumoniae, but it also has activity against some Gram-negative bacteria, such as Escherichia coli and Klebsiella pneumonia.
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Dosage Forms and Administration
Cephalexin is available in several forms to suit different patient needs:
Available Forms
| Dosage Forms | Strengths |
|---|---|
| Oral Capsules | 250 mg, 333 mg, 500 mg, 750 mg |
| Oral Suspension | 125 mg/5 mL, 250 mg/5 mL |
| Oral Tablets | 250 mg, 500 mg |
How to Take Cephalexin
- With or Without Food: Cephalexin can be taken with meals to reduce stomach upset.
- Swallow Whole: Do not crush, chew, or break the capsules or tablets.
- Shake the Suspension: If using the liquid form, shake the bottle well before measuring the dose. Use a measuring device (not a household spoon) for accuracy.
Typical Dosages
- Adults: The usual dose is 250 mg to 500 mg every 6 to 12 hours, depending on the severity of the infection.
- Children: The dose is based on body weight, typically 25 mg to 50 mg per kg per day, divided into multiple doses.
Side Effects of Cephalexin
Like all medications, cephalexin can cause side effects. These can range from mild to severe.
Common Side Effects
| Side Effect | What to Do |
|---|---|
| Nausea and vomiting | Take with food. |
| Diarrhea | Stay hydrated; inform your doctor if severe. |
| Upset stomach | Take with meals. |
| Stomach pain | Contact your doctor if persistent. |
Serious Side Effects
| Side Effect | What to Do |
|---|---|
| Severe allergic reactions (e.g., swelling, trouble breathing) | Seek emergency help immediately. |
| Seizures | Stop cephalexin and contact your doctor. |
| Antibiotic-associated diarrhea (e.g., watery diarrhea, blood in stool) | Inform your doctor right away. |
| Blood disorders (e.g., jaundice, unusual weakness) | Seek medical attention immediately. |
Warnings and Precautions
Who Should Avoid Cephalexin?
- People with a history of allergic reactions to cephalexin, other cephalosporins, or penicillins.
- Those with severe kidney disease (dosage adjustments may be needed).
Special Populations
- Pregnant Women: Cephalexin is generally considered safe during pregnancy, but consult your doctor.
- Breastfeeding Mothers: Cephalexin passes into breast milk but is usually safe for breastfeeding infants.
- Elderly Patients: May require lower doses due to reduced kidney function.
Drug Interactions
Cephalexin can interact with other medications. Always inform your doctor about all the drugs, supplements, and herbal products you are taking.
Common Drug Interactions
| Medication Class | Examples |
|---|---|
| Probenecid | May increase cephalexin levels in the blood. |
| Metformin | Cephalexin may increase metformin levels, raising the risk of side effects. |
| Blood thinners | Increased risk of bleeding. |
Overdose and Missed Dose
What to Do in Case of Overdose
If you or someone else takes too much cephalexin, seek emergency medical help immediately. Symptoms of overdose may include:
- Severe nausea and vomiting
- Diarrhea
- Blood in urine
What to Do If You Miss a Dose
- Take the missed dose as soon as you remember.
- If it’s almost time for your next dose, skip the missed dose and continue with your regular schedule.
- Do not double the dose to make up for a missed one.
Storage Instructions
Oral Tablets and Capsules
- Store at room temperature (68°F to 77°F or 20°C to 25°C).
- Keep in a tightly closed container, away from light and moisture.
Oral Suspension
- Refrigerate the liquid form (do not freeze).
- Discard any unused suspension after 14 days.
Tips for Taking Cephalexin Safely
- Complete the full course: Do not stop taking cephalexin early, even if you feel better.
- Stay hydrated: Drink plenty of fluids to prevent kidney problems.
- Monitor for side effects: Report any unusual symptoms to your doctor.
- Avoid alcohol: While not directly interacting, alcohol can weaken your immune system.
- Use probiotics: To reduce the risk of antibiotic-associated diarrhea, consider taking probiotics.
Frequently Asked Questions (FAQs)
1. Can I drink alcohol while taking cephalexin?
While there is no direct interaction, alcohol can weaken your immune system and delay recovery.
2. How long does it take for cephalexin to work?
You may start feeling better within 1 to 2 days, but it’s important to complete the full course of treatment.
3. Can cephalexin cause yeast infections?
Yes, like other antibiotics, cephalexin can disrupt the balance of bacteria in your body, leading to yeast infections.
4. Is cephalexin safe for children?
Yes, cephalexin is commonly prescribed for children in appropriate doses based on their weight.
Conclusion
Cephalexin is a reliable and effective antibiotic for treating a variety of bacterial infections. You can use it safely and effectively by understanding its uses, side effects, and precautions. Always follow your healthcare provider’s instructions and complete the full course of treatment to ensure the best results. If you have any questions or concerns, consult your doctor or pharmacist.