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Cephalexin

Cephalexin is an antibiotic used to treat infections caused by certain bacteria. Learn how to use the medication, its common side effects, special precautions to watch out for, and more.
  • Article last reviewed 29 June 2026
  • 7 mins read

What is this medication for?

This medication is also known as Cefalexin. Cephalexin is an antibiotic used to treat infections caused by certain bacteria. These may include infections of the lung, urine, skin, and soft tissue.

How should I take or use this medication?

  • Tablets or capsules: swallow with some water.
  • Capsules: If there is swallowing difficulties, open capsule, pour out content and mix with a spoonful of water.
  • Powder for suspension: add the amount of water as directed by your healthcare professional.
    • Click on this link for step-by-step instructions on how to mix the powder into a suspension before administration.
  • You may take this medication with or without food.
  • Take the medication as prescribed by the doctor, at evenly spaced intervals, to keep a constant level of medication in the body.
  • You should complete each course of antibiotics even if you feel better as an incomplete treatment might cause the infection to return or cause antibiotic resistance. When antibiotic resistance happens, the antibiotic will not be able to control the growth or kill the bacteria anymore.

What should I do if I forget to take or use this medication?

If you forget to take a dose, take it as soon as you remember if it is not close to the next dose. Otherwise, you should skip the dose and take the next dose at the usual time. Try to leave a gap of at least 4 hours between doses.

Do not take two doses together to make up for the missed dose.

What precautions should I take when taking or using this medication?

Inform your healthcare professional if:

  • You are allergic to penicillins, such as Amoxicillin, other medications in the same class as Cephalexin, such as Cefadroxil or Cefadroxil, or any of the other ingredients of this medication
  • You are pregnant, planning to become pregnant, or breastfeeding
  • You are taking any other medications, including supplements, traditional medications and herbal remedies
  • You have kidney problems
  • You are taking warfarin, a medication to thin your blood
  • You are taking probenecid, a medication used to treat gout

If you have any question about this medication, please discuss with your healthcare professional.

What are some common side effects of this medication? ​

Some common side effects that you may experience include:

  • Mild diarrhoea
  • Stomach pain
  • Nausea or vomiting

Taking the medication with or after food may reduce these symptoms.

What are some rare but serious side-effects that I need to seek medical advice immediately? 

The symptoms of a drug allergy include one or more of the following: 

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

You can also find out about drug allergies by watching these videos:
They are available in English, 中文, Melayu and தமிழ்: Drug Allergies

Some rare but serious side effects include: 

  • Serious diarrhoea that does not stop, blood or mucus in your stools
  • Very bad stomach pain or cramps
  • Signs of an infection such as fever, chills, bad sore throat, pain when you pass urine or have mouth sores or wounds that do not heal
  • Signs of low platelet levels such as unusual bleeding or bruising
  • Signs of liver injury, which may include dark coloured urine, light coloured stools, severe nausea and vomiting, loss of appetite, stomach pain or yellowing of skin or eyes

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

Antibiotic powders that have been mixed with water may have different storage conditions. Follow the instructions as stated on the label or as advised by your healthcare professional. Discard any unused portion after the duration stated on the label.

How do I throw away this medication safely? ​

Pack the medication into a bag and bring it back to the pharmacy where you received the medication from.

Disclaimer

Please take note that the above is not a complete list of all possible side-effects. If you have any concerns about your medication or if you have other side-effects that you think are caused by this medication, please consult your doctor or pharmacist. If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information. 

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (NHG Health, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.