Cefalexin for infection
Keflex
Revu par Dr Colin Tidy, MRCGPDernière mise à jour par Michael Stewart, MRPharmSLast updated 26 nov. 2024
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Before you take cefalexin, make sure your doctor knows if you have ever had an allergic reaction to an antibiotic.
Space out your doses evenly over the day and complete the full course.
The most common side effect of cefalexin is diarrhoea, which is usually mild and soon passes.
If diarrhoea becomes severe or lasts for more than 24 hours, you should speak with your doctor.
Dans cet article:
Video picks for Médicaments pour le traitement des infections
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About cefalexin
Type de médicament | A cephalosporin antibiotic |
Utilisé pour | Treatment (and sometimes prevention) of infection |
Aussi appelé | Cephalexin, Keflex® (USA) |
Disponible sous forme de | Capsules, tablets, and oral liquid medicine |
What is cefalexin used for?
Retour au sommaireCefalexin is a type of antibiotic used to treat bacterial infections such as urinary tract infections, skin infections, chest et throat infections, infections de l'oreille et dental infections.
It is suitable for adults and children and can be taken during pregnancy.
Some people who are allergic to penicillin antibiotics may not be able to take cefalexin, so make sure your doctor knows if you have ever had an allergic reaction to any other antibiotic.
Cefalexin treats an infection by killing the bacteria that are causing it.
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Side effects of cefalexin
Retour au sommaireCommon side effects of cefalexin are:
Diarrhée.
Sensation de nausée.
Indigestion.
Maux d'estomac.
Thrush.
You will find a full list in the manufacturer's information leaflet supplied with the medicine.
Les effets indésirables s'améliorent souvent à mesure que votre corps s'adapte au nouveau médicament, mais parlez à votre médecin ou pharmacien si l'un des effets suivants persiste ou devient gênant.
How to manage cefalexin side effects
Retour au sommaireCefalexin side effects | Que puis-je faire si je ressens cela ? |
Diarrhée | Drink plenty of water to replace the lost fluids. If the diarrhoea continues for longer than 24 hours, becomes severe, or contains blood, please let your doctor know immédiatement |
Indigestion, stomach ache, feeling sick | Stick to simple foods. If you are not already doing so, try taking your doses after meals |
Muguet | Speak with your doctor or pharmacist for advice |
Important: if you develop an itchy rash, swollen face or mouth, or have difficulty breathing, these can be signs that you are allergic to the antibiotic. Do not take any more doses, and speak with your doctor or go to your local accident and emergency department straightaway.
If you experience any other symptoms which you think may be due to the antibiotic, please speak with your doctor or pharmacist for further advice.
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Who should not take cefalexin?
Retour au sommaireSome medicines are not suitable for people with certain conditions. Before starting cefalexin it is important that your doctor knows:
If you have ever had an allergic reaction to a medicine. It is particularly important that you tell your doctor if you have had a bad reaction to a penicillin or cephalosporin antibiotic.
Si vous avez des problèmes avec le fonctionnement de vos reins.
If you are pregnant, trying for a baby or breastfeeding. Although cefalexin is not known to be harmful to babies, it is still important that you tell your doctor if you are expecting or breastfeeding a baby.
Si vous prenez ou utilisez d'autres médicaments. Cela inclut tous les médicaments que vous prenez et qui sont disponibles à l'achat sans ordonnance, ainsi que les médicaments à base de plantes et complémentaires.
How to take cefalexin
Retour au sommaireRead the leaflet inside the pack before starting cefalexin. It explains how the antibiotic works and lists possible side effects.
Take cefalexin 2-4 times a day, as directed by your doctor. Check the label for your exact dose and timing.
For children: if using liquid cefalexin, carefully measure each dose as instructed.
Treatment usually lasts 5-7 days, but your doctor may adjust this. Always follow their advice.
For UTI prevention: you may take one dose daily, usually in the evening.
You can take cefalexin before or after food, but it may work a bit faster before meals.
Space doses evenly through the day and complete the full course, even if you feel better.
If you miss a dose, take it as soon as you remember. Do not take twice to make up for a missed one.
Tirer le meilleur parti de votre traitement
Retour au sommaireTell your doctor or healthcare provider if you’re taking cefalexin before any operation or medical test, as it can affect some test results.
Antibiotics can sometimes cause thrush (oral ou vaginal). If this happens, speak to your doctor or pharmacist.
If you take the contraceptive pill and have vomiting or diarrhoea for more than 24 hours while on antibiotics, the pill may be less effective. Ask your doctor or pharmacist about extra contraception. No extra precautions are needed if symptoms last less than 24 hours.
Cefalexin can stop the oral vaccin oral contre la typhoïde from working properly. Tell the person giving you any vaccines that you’re taking this antibiotic.
How to store cefalexin
Retour au sommaireGardez tous les médicaments hors de la portée et de la vue des enfants.
Store tablets and capsules in a cool, dry place, away from direct heat and light.
If you have been given liquid medicine, store it in a refrigerator. It will have been made up freshly by the pharmacy and lasts for 14 days, so please remember to check the expiry date, and do not use it after this date.
Informations importantes sur tous les médicaments
Retour au sommaireInformations importantes sur tous les médicaments
Do not take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
Ce médicament est pour vous. Ne le donnez jamais à d'autres personnes, même si leur état semble être le même que le vôtre.
Si vous achetez des médicaments, vérifiez avec un pharmacien qu'ils sont sûrs à prendre avec vos autres médicaments.
Si vous subissez une opération ou un traitement dentaire, informez la personne qui effectue le traitement des médicaments que vous prenez.
Ne gardez pas de médicaments périmés ou indésirables. Apportez-les à votre pharmacie locale qui s'en débarrassera pour vous.
Si vous avez des questions concernant ce médicament, demandez à votre pharmacien.
Signaler les effets secondaires d'un médicament ou d'un vaccin
Si vous ressentez des effets secondaires, vous pouvez les signaler en ligne via le Yellow Card website.
Questions fréquemment posées
Retour au sommaireHow quickly does cefalexin work?
Cefalexin usually starts to work within an hour after taking the first dose. Most people notice improvement in symptoms, such as reduced pain, fever, or redness, within the first 1-2 days of treatment.
Is cefalexin safe to use during pregnancy?
Yes, cefalexin is considered safe to use during pregnancy as there is no evidence that it causes harm to the baby. However, always let your doctor or midwife know you are pregnant before taking cefalexin.
Does cefalexin contain penicillin?
No, cefalexin does not contain penicillin. However it is a cephalosporin antibiotic, which is chemically related to penicillin. People who are allergic to penicillin may also be allergic to cefalexin, so it is important to inform your doctor if you have a penicillin allergy before taking cefalexin.
Can you drink alcohol with cefalexin?
Yes, you can drink alcohol with cefalexin. However, it is advised to only drink in moderation as alcohol may increase side effects such as stomach upset, dizziness, or drowsiness.
Can cefalexin cause a rash?
Yes, cefalexin can cause a rash as a side effect and is usually a sign of an allergic reaction. If you develop a mild rash, contact your doctor for advice. If you have trouble breathing or swelling of the face, lips, tongue, or throat, seek medical help immediately.

Vous n'êtes pas sûr de mélanger des médicaments ?
Vérifiez les interactions possibles entre les médicaments, les compléments et les aliments avant de les prendre ensemble.
Lectures complémentaires et références
- Manufacturer's PIL, Cefalexin 250 mg and 500 mg Capsules; Aurobindo Pharma - Milpharm Ltd; The electronic Medicines Compendium. Dated August 2024.
- Manufacturer's PIL, Cefalexin 125 mg and 250 mg/5 ml Powder for Oral Suspension; Aurobindo Pharma - Milpharm Ltd; The electronic Medicines Compendium. Dated March 2024.
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About the authorView full bio

Michael Stewart, MRPharmS
Medicine Leaflet Review Manager – Contractor, Pharmacist
BPharm (Hons), MRPharmS
Michael is a community pharmacist practicing in the Midlands and South Yorkshire with more than 20 years’ experience advising on medicines and medical conditions. He has a strong background in healthcare training, having produced and delivered training courses for pharmacy teams and staff of residential care settings, including nurses. He has also contributed to pharmacy advisory boards for the management of low acuity conditions in the community.
About the reviewerView full bio

Dr Colin Tidy, MRCGP
Médecin généraliste, Auteur médical
MBBS, MRCGP, MRCP (Paediatrics), DCH
Dr Colin Tidy is an NHS Doctor, based in Oxfordshire.
Historique de l'article
Les informations sur cette page sont rédigées et examinées par des cliniciens qualifiés.
Prochaine révision prévue : 26 nov. 2027
26 nov. 2024 | Dernière version

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