Key points about cefalexin

  • Cefalexin is an antibiotic used to treat different infections caused by bacteria.
  • Cefalexin is also called Cefalexin (Sandoz)® and Cefalexin ABM®.
  • Find out how to take it safely and possible side effects.
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Cefalexin is an antibiotic used to treat infections caused by bacteria, such as infections of the urinary tract, skin or chest. It can also be used for dental infections or ear infections. It works by killing or stopping the growth of bacteria (bugs) and gets rid of the infection. Cefalexin does not work against infections caused by viruses. 

In Aotearoa New Zealand cefalexin is available as capsules and liquid.

  • The dose of cefalexin will be different for different people depending on the type of infection and your age. 
  • The usual adult dose is 250 mg four times a day, or 500 mg two, three or four times a day. Some people may need a larger dose. 
  • The dose for children will depend on their body weight. It may be given two, three or four times a day.
  • Your doctor will advise you how long to take cefalexin for (usually 5 to 7 days).
  • Always take your cefalexin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much cefalexin to take, how often to take it, and any special instructions.

  • Timing of your doses: You can take cefalexin with or without food. Swallow your capsule with a drink of water. Do not chew them. Try to space your doses evenly throughout the day.  
    • Two times a day: this should be in the morning and in the evening. 
    • Three times each day: this should be in the morning, early afternoon and at bedtime. 
    • Four times each day: this should be about 4 hours apart, for example 7am, 11am, 3pm and 7pm.  
  • Missed dose: If you forget to take your dose at the correct time, take one as soon as you remember. Try to take the correct number of doses each day. Do not take two doses at the same time to make up for a forgotten dose.
  • Finish the course. It is best to take the whole course of antibiotics for the number of days your doctor has told you to. Do not stop taking it, even if you feel your infection has cleared up. 

For information on how to give cefalexin to children, see cefalexin information for parents and carers.(external link)

Here are some things to know when you're taking cefalexin. Other things may be important as well, so ask your healthcare provider what you should know about.

  • Cefalexin does not have direct interaction with alcohol. This means that most people could have the occasional drink while taking it without any serious problems. However, if cefalexin makes you feel sick (nausea), do not drink alcohol as it will make you feel worse.
  • If you are taking the contraceptive pill, you do not usually need to use additional contraception if you're taking cefalexin. But if the antibiotics or the illness they're treating cause diarrhoea or vomiting, lasting more than 24 hours, absorption of the contraceptive pill may be affected. If this happens, ask your doctor or pharmacist for advice about contraception over the following few days. 

Like all medicines, cefalexin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Feeling sick (nausea) or vomiting
  • Dizziness, headache
  • Try taking cefalexin with food.
  • Tell your doctor if troublesome.
  • If you have been vomiting and are also taking the oral contraceptive pill, let your doctor or pharmacist know.
  • Diarrhoea (runny poos)
  • This may settle after a few days.
  • Tell your doctor if troublesome.
  • If you have been diarrhoea and are also taking the oral contraceptive pill, let your doctor or pharmacist know.
  • Vaginal itching, soreness or discharge (thrush)
  • Ask your doctor or pharmacist for advice.
  • Signs of problems with your liver such as yellow skin and eyes, dark urine and stomach pain
  • Tell your doctor immediately or ring HealthLine 0800 611 116
  • Signs of allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing
  • Tell your doctor immediately or ring HealthLine 0800 611 116
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

For adults: cefalexin(external link) New Zealand Formulary Patient Information
For children: cefalexin(external link) New Zealand Formulary for Children



5 questions to ask about your medications(external link) Health Quality and Safety Commission, NZ, 2019 English(external link), te reo Māori(external link)


Cefalexin paediatric dose calculator


  1. Cefalexin(external link) New Zealand Formulary
  2. Antibiotics: choices for common infections(external link) BPAC, 2017

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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