Cephalexin: Uses, Interactions & Considerations

Cephalexin is a cephalosporin antibiotic, commonly prescribed to treat bacterial infections. If you’ve been prescribed this medication or are considering it as part of your treatment plan, here’s what you need to know.

Cephalexin, often available under the brand name Keflex, also has generic versions that offer the same therapeutic benefits but may differ in pricing and packaging.

What is Cephalexin Used For?

Cephalexin, often available in the form of cephalexin 500 mg or cephalexin 250 mg tablets, serves a vital role in treating a broad range of bacterial infections. To break it down:

  • Primary Uses: This medication is vital in treating bacterial infections, making it a handy tool against ailments like bronchitis, pneumonia, and more.
  • How It Works: Cephalexin operates by halting the growth of bacteria. It’s essential to note that it won’t work for viral infections, like the common cold or flu.
  • Misuse Concerns: Unnecessary or incorrect use can reduce the effectiveness of this antibiotic.

How to Use Cephalexin

Following the prescribed guidelines is crucial:

  • Administration: Typically taken by mouth every 6 to 12 hours, with or without food.
  • Dosage: Based on your medical condition, weight (in children), and how your body responds to the treatment.
  • Consistency: For optimal results, it’s crucial to consume the antibiotic at evenly spaced intervals and complete the entire course, even if you feel better after a few days.

Cephalexin Side Effects

While cephalexin is generally well-tolerated, there are some potential side effects:

  • Common Reactions: These might include diarrhea, nausea, and an upset stomach.
  • Serious Reactions: In rare cases, patients might experience severe intestinal conditions or even allergic reactions. If you observe symptoms like relentless diarrhea, abdominal pain, rash, or difficulty breathing, seek medical attention immediately.

Precautions with Cephalexin

Before you jump into the treatment, consider the following:

  • Allergies: Inform your doctor if you’re allergic to cephalexin or related antibiotics. Wondering, “Is cephalexin a penicillin?” While not penicillin, some people allergic to penicillin may also react to cephalosporins.
  • Medical History: Be transparent about any kidney disease or stomach/intestinal diseases.
  • Interactions: For instance, cephalexin vs amoxicillin might have different interactions. Always consult your physician.

Additional Considerations

  • Alcohol: Combining cephalexin and alcohol can exacerbate side effects or decrease the drug’s effectiveness.
  • Infections: Using cephalexin for prolonged periods can lead to oral thrush or yeast infections.
  • During Pregnancy: Only use cephalexin when clearly needed, discussing potential risks with your doctor.

Interactions and Overdose

  • Possible Interactions: Cephalexin can interact with drugs like dofetilide and may interfere with lab tests.
  • Overdose: If you suspect an overdose with symptoms such as severe vomiting or seizures, seek emergency help.

Note for Patients

Cephalexin is for individual use. It’s designed for your current condition and shouldn’t be reused for other infections unless directed. Regularly scheduled medical and lab tests can monitor the medication’s effect.


Store the tablets at room temperature, away from moisture. The suspension should be refrigerated and used within 14 days. Always keep medications out of reach of children.

Final Thoughts

Whether you’re taking cephalexin for sinus infection or any other bacterial infection, understanding its uses, potential side effects, and precautions can ensure a smoother treatment journey. Always consult your healthcare provider for personalized guidance.