Cephalexin - Use | Overdose | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Cephalexin is a drug from the group of cephalosporin antibiotics. Cephalexin works by killing bacteria, and therefore is used to treat infections.

Cephalexin is used to treat the following infections:

  • Respiratory tract infections such as:
    • sinusitis,
    • pharyngitis,
    • sore throat,
    • pneumonia,
    • bacterial bronchitis
  • Otitis media (middle ear inflammatory disease)
  • Skin and soft tissue infections
  • Urinary tract infections
  • Tooth abscess


Cephalexin should be avoided in the following conditions:

  • If you are allergic to Cephalexin, or other antibiotics such as:
    • amoxicillin (Sinacilin),
    • co-amoxiclav (Panklav),
    • cefepime,
    • ceftriaxone,
    • ceftibuten,
    • cefaclor,
    • cefdinir and other similar medicines. If you are experiencing symptoms of an allergy, such as:
      • skin rash,
      • itching of the skin,
      • redness of the skin,
      • swelling of the face,
      • swelling of the tongue,
      • difficulty breathing, contact your doctor immediately. Allergies can cause anaphylactic shock, that may be fatal.
  • If you have liver or kidney disorders.
  • If you have diabetes.

Concomitant use of Cephalexin with alcoholic beverages is not recommended.

Cephalexin like all other antibiotics can cause diarrhea. Consult your doctor about the medicine you need to take to treat diarrhea.

Use of Cephalexin during pregnancy and breastfeeding

According to FDA, Cephalexin belongs to group B (FDA: Group B). This means that animal studies have shown that Cephalexin is not harmful to the fetus, but there are no studies on humans. Cephalexin should be used during pregnancy only if the benefit to the mother outweighs the risk to the child.

Cephalexin passes into breast milk and may harm your baby. Avoid breastfeeding while using Cephalexin.

How to use Cephalexin

The usual dose of Cephalexin for adults is 500 mg three times a day (every 8 hours).

The dose may be increased according to the severity of infection.

To treat urinary tract infections Cephalexin is used in a dose of 250 mg 4 times a day or 500 mg twice a day.

In children above the age of 6, recommended dose is 250 mg, three times a day.

In children below the age of 6, Cephalexin is recommended in the form of syrup.

It is very important to use Cephalexin for as long as your doctor tells you to, even if you feel better. If you do not use Cefalexin for as long as your doctor tells you to, it will not kill all bacteria. Those bacteria that survive will develop a mechanism to fight against Cephalexin. Therefore, the next time when you get an infection, Cephalexin will not help you to treat infection. Therefore it is very important to use Cephalexin for as long as your doctor tells you to (usually not less than 7days!). Cephalexin should also not be used over a long time period.

Cephalexin should be taken with a full glass of water.

If children cannot swallow the capsules, we recommend you to give Cephalexin to your child in the form of syrup.


If you take more Cephalexin than your doctor tells you to, immediately contact your doctor. Symptoms of an overdose include:

  • difficulty urinating,
  • abdominal pain,
  • nausea,
  • vomiting,
  • diarrhea (blood in stool may occur).

If you are experiencing any of these symptoms, contact your doctor immediately.

Use with other medicines (Interactions)

Cephalexin should be avoided in combination with the following medicines:

  • Metformin, used to treat diabetes
  • Aallopurinol and probenecid used to treat gout
  • Medciines used to treat thrombosis such as:
    • warfarin (Farin),
    • acenocoumarol (Sintrom, Sinkum 4). Concomitant use of Cephalexin with these medications increases the risk of bleeding.

Tell your doctor about all medications and herbal medicines you are taking.

Side effects

Cephalexin may cause the following side effects:

  1. nausea,
  2. abdominal pain,
  3. vomiting,
  4. diarrhea (blood in stool may occur),
  5. digestive disorders,
  6. anemia,
  7. low platelets count (thrombocytopenia),
  8. a fungal infection of the vagina,
  9. dizziness,
  10. headache,
  11. mild liver damage,
  12. allergy, and others.

If you are experiencing any side effects, contact your doctor.

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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