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Brand Name(s) : Ceporex, Keflex
Side Effects


Cefalexin should be used with caution by:

It should not be used by people who are allergic to cefalexin or have a known allergy to the cephalosporin group of antibiotics.

Also see list of precautions and interactions


Tablets or capsules: Do not store above 25ºC. Keep containers tightly closed.

Oral suspensions: the dry powder should be stored below 25ºC, whereas the suspension made up by the pharmacist should be stored in a refrigerator (2°C-8°C) and used within 14 days.


What is it used for?

  • Cefalexin is used to treat certain types of bacterial infection.
  • It is a type of antibiotic known as a cephalosporin.
  • It is used to kill certain types of bacteria that cause infections.
  • In general this drug is used to treat a variety of bacterial infections, as it is a broad spectrum antibiotic. It is often used to treat urinary tract infections that have not responded to other drugs.
  • Benefits of being on this drug can include killing or stopping the bacterial growth of sensitive bacteria bringing relief from the symptoms of the infection.

Listed below are the typical uses of cefalexin.

  • Bacterial infections of the lungs and airways (respiratory tract), such as bronchitis and mild to moderate pneumonia
  • Bacterial infections of skin or soft tissue, such as wound infection
  • Bacterial infections of bones and joints
  • Bacterial infections of the urinary tract
  • Bacterial infections of the genitals
  • Bacterial infections of teeth or gums
  • Bacterial infections of middle ear (otitis media)

On occasion your doctor may prescribe this medicine to treat a condition not on the above list.


How often do I take it?

  • This medication is available as tablets, capsules and as an oral suspension/syrup. The oral suspension is made up from cefalexin granules by adding water. The pharmacist normally does this at the time of dispensing.
  • Take this medication orally usually daily in divided doses, with or without food. Most infections require dosage every eight hours, but an appropriate frequency will be prescribed by doctor.
  • Use this medication for duration of prescription in order to get the most benefit from it.
  • Remember to use it at the same time each day - unless specifically told otherwise by your doctor.
  • It may take up to several days before the full benefit of this drug takes effect, depending on the type of infection.
  • Certain medical conditions may require different dosage instructions as directed by your doctor.

What dose?

  • Dosage is based on your age, gender, medical condition, response to therapy, and use of certain interacting medicines.

Do I need to avoid anything?

  • This medication is not known to affect driving or operating machinery. However, people should be aware of how they react to the medication before initiating these activities. Consult your doctor or pharmacist for more details.

When can I stop?

  • Always complete the full course as prescribed by your doctor.


If any of these persist or you consider them severe then inform doctor or pharmacist.

Tell your doctor immediately if you develop any of the following symptoms:

  • Swelling of face, lips, tongue or throat
  • Rash or itching spots on arms and legs or severe, extensive, blistering skin rash
  • Fever, sore throat and joint pain with severe, extensive, blistering skin rash
  • Watery and/or bloody diarrhoea

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine (which includes vaccines, herbals and over the counter medicines) that you are taking. It is run by the medicines safety watchdog called the Medicines and Healthcare products Regulatory agency (MHRA). Please report any suspected side effect on the Yellow Card Scheme website.


Before taking cefalexin, tell your doctor or pharmacist if you are allergic to it; or to other cephalosporins; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have:

  • Known allergy to the cephalosporin group of antibiotics

Before using this medication, tell your doctor or pharmacist your medical history, especially any of the following

  • Penicillin-sensitivity
  • Allergic reactions to other drugs
  • Severe kidney problem

Before having surgery, tell your doctor or dentist that you are taking this medication.

Does alcohol intake affect this drug?

  • Alcohol intake is not known to affect cefalexin.

The elderly: cefalexin should be used with caution in the elderly due to declining kidney function; therefore dosage adjustment may be necessary.

Pregnancy and breastfeeding - please ensure you read the detailed information below


Cefalexin is suitable to take during pregnancy, although caution should be exercised. Ask your doctor or pharmacist for advice before taking medication.

It is sensible to limit use of medication during pregnancy whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Cefalexin is suitable to take if you are breastfeeding. However, caution should be taken when cefalexin is administered to breastfeeding women as cefalexin is excreted in breast milk. Ask your doctor or pharmacist for advice before taking medication.

It is sensible to limit use of medication during breastfeeding whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Before using this medicine, tell your prescriber of all the medicines you are taking including prescription medicines and medicines you have bought over the counter without a prescription. Tell your prescriber if you are taking vitamins or complementary remedies such as herbal products, as these can also interact with medicines.

If you are taking more than one medicine, these may interact with each other. Your prescriber may decide to use medicines which interact with each other if the benefit outweighs the risks. In these cases, the dose of your medicines may need to be adjusted or you may be monitored more closely.

The following medicines may interact with cefalexin:

  • Blood-thinning medicines, such as warfarin
  • Probenecid used to treat gout
  • Metformin used in the treatment for diabetes
  • Aminoglycosides and other cephalosporins (treatment for infections)
  • Diuretics (also known as water tablets) such as furosemide

This information does not contain all possible interactions. Therefore, tell your prescriber of all the products you are using before taking this medicine.

If you have a question or want to discuss anything about your medicine, speak to your local pharmacist.


Symptoms of overdose may include nausea, vomiting, epigastric distress (stomach pain), diarrhoea and haematuria (presence of blood in the urine).

In the event of severe overdosage, general supportive care in hospital is recommended, including close clinical and laboratory monitoring of blood, kidney and liver functions, and blood clotting status until the patient is stable.

If you think you, or someone you care for, might have accidentally taken more than the recommended dose of cefalexin or intentional overdose is suspected, contact your local hospital, GP or if in England call 111. In Scotland call NHS 24. In Wales, call NHS Direct Wales. In the case of medical emergencies, always dial 999.


If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

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Source: Selected from data included with permission and copyrighted by Boots UK Limited. This copyrighted material is sourced from a licensed data provider and is not for distribution, except as may be authorised by the applicable terms of use.
CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse events, nor should it be construed to indicate that use of a particular medicine is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any medicine, changing any diet, or discontinuing any course of treatment.

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