Cephalexin is an antibiotic that belongs to the class of β-lactam antibiotics. It is primarily used to treat infections caused by susceptible bacteria, such as abscesses, urinary tract infections, and respiratory tract infections. This medication inhibits the synthesis of bacterial cell walls, thereby killing or inhibiting bacterial growth, and is suitable for various infections caused by Gram-positive bacteria and some Gram-negative bacteria.
The therapeutic range of cephalexin includes skin and soft tissue infections, otitis media, sinusitis, and urinary tract infections caused by specific bacteria. Its advantages include good absorption and relatively few side effects, making it a common first-line treatment. However, it is important to note that this medication is ineffective against viral infections and should not be misused to avoid antibiotic resistance issues.
The generic name of this medication is Cephalexin, and it may have different brand names in different countries or regions. Common trademarks include:
Cephalexin belongs to the first generation of cephalosporin antibiotics, which have broad-spectrum antibacterial activity effective against various Gram-positive bacteria and some Gram-negative bacteria. Its chemical structure is similar to that of penicillin, but it has lower resistance, thus classified as a different category of antibiotics.
The key to this drug classification lies in its mechanism of action and antibacterial spectrum. First-generation cephalosporins primarily target bacterial infections of the skin, respiratory tract, and urinary system, while later generations of cephalosporins target a wider range of infection types. When using, it is necessary to select the appropriate category based on the type of infection and the pathogen.
The main indications for cephalexin include:
Additionally, this medication is also suitable for treating pharyngitis and cellulitis caused by streptococci. In specific circumstances, physicians may expand the indications based on clinical judgment, but this should be based on bacterial culture results and sensitivity testing.
Mild side effects include:
Severe side effects, although rare, require immediate discontinuation of the medication and medical attention:
The following patients should use caution:
Use during pregnancy and breastfeeding requires physician assessment of risks. According to the FDA pregnancy categories, cephalexin is classified as Category B, but clinical use should still be based on individual judgment. Severe warnings include:
Interactions may occur with the following medications:
Simultaneous use of bacteriostatic antibiotics (such as tetracycline) may reduce the efficacy of cephalexin. During treatment, avoid excessive alcohol intake, as some patients may experience disulfiram-like reactions. Always inform your physician or pharmacist before using any prescription or over-the-counter medications.
Typical adult dosage:
Pediatric dosage is calculated based on weight, usually 20-40 mg per kilogram, divided into doses. It is essential to complete the full course of treatment as prescribed, even if symptoms improve, to avoid resistance. It should be taken either one hour before or after meals to enhance absorption.
If a dose is missed and it is less than 3 hours late, it should be taken immediately and the next dose time adjusted; if it is close to the next scheduled dose, skip the missed dose and return to the regular schedule without doubling the dose. If multiple doses are missed or irregular dosing occurs, contact a physician immediately to assess whether the treatment regimen needs adjustment.
If an overdose occurs, it may cause severe diarrhea, vomiting, or dizziness. Seek immediate medical attention and bring the medication packaging for the physician to assess the level of toxicity. Severe overdose may require gastric lavage or activated charcoal to absorb unabsorbed medication, and severely affected patients may need to be hospitalized for observation.
Cephalexin can be taken with or without food, but if gastrointestinal discomfort occurs, it can be taken with a small amount of food to alleviate discomfort. Taking it with food does not significantly reduce its efficacy, but it is advisable to avoid taking it with high-calcium or high-iron foods (such as dairy products) to prevent absorption interference.
What should I do if I experience gastrointestinal discomfort while taking cephalexin?Mild diarrhea or nausea can be alleviated by dividing the doses, reducing the single dose, or switching to an enteric-coated formulation. If symptoms persist for more than 48 hours, or if severe abdominal pain or bloody stools occur, discontinue the medication immediately and consult a physician. Supplementing with probiotics or a low-fiber diet can help restore intestinal health.
What is the effect of taking cephalexin with antacids (such as proton pump inhibitors)?Taking it with antacids may reduce the absorption of cephalexin; it is recommended to space the two medications by 2 to 3 hours. If long-term use of antacids is necessary, inform your physician to adjust the timing of medication to avoid affecting the efficacy of the antibiotic.
What should I do if I miss a dose?If the missed dose is less than 4 hours late, take it as soon as possible and return to the original schedule; if it is close to the next scheduled dose (more than 6 hours), skip the missed dose and do not double the dose. Do not increase the single dose due to a missed dose to avoid toxicity reactions.
Are there any specific dietary or activity restrictions while using cephalexin?No need to limit exercise, but during treatment, avoid excessive sun exposure, as a few patients may experience skin reactions due to photosensitivity. It is advisable to avoid excessive alcohol intake, as although the medication itself does not directly induce disulfiram reactions, drinking may weaken immune recovery.
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