Meds and you

Updated 11 February 2013


Cephalexin (also known as cefalexin) is a broad spectrum antibiotic effective for treating a variety of bacterial infections.


Cephalexin is the active ingredient of CPL Alliance Cephalexin and Ranceph.

General Information

Cephalexin (also known as cefalexin) is a broad spectrum antibiotic effective for treating a variety of bacterial infections. It is frequently prescribed to treat infections of the urinary tract, respiratory tract (including sinusitis, middle ear infections, pharyngitis, tonsillitis and pneumonia and bronchitis) and skin and soft tissue infections caused by susceptible bacteria.

It is important to note that this medication is only effective against bacterial infections. If your infection is the result of a viral or fungal infection it will be ineffective.

Antibiotic resistance - when bacteria develop the ability to defend themselves against the effect of an antibiotic - occurs frequently with many antibiotics. This mostly happens when patients do not complete the prescribed course, allowing antibiotics to recover from treatment, and by using antibiotics for non-bacterial infections such as colds and flu.

Persons who are allergic to penicillin should take cephalexin with caution. Although it is not penicillin, cross-sensitivity - meaning that you may also be allergic to this drug - may occur.

How does cephalexin work?

Cephalexin weakens the bacterial cell wall and allows water to enter the cell, causing cells to burst.

Fast facts

Drug schedule: Schedule 4

Available as: Cephalexin is available as capsules and oral suspension.

What does it do? Cephalexin has an anti-biotic action.

Overdose risk: Low

Dependence risk: Low

Is cephalexin available as a generic? Yes

Is cephalexin available on prescription only? Yes

User information

Onset of effect: Within 1 hour

Duration of action: Up to 12 hours

Dietary advice: If taken with food, gastrointestinal symptoms may be less severe.

Stopping this medicine: Do not stop taking this medication until you have finished the course as prescribed by your doctor. Infection may recur with premature discontinuation.

Prolonged use: Cephalexin is usually given only for short courses of treatment

Special precautions

Consult your doctor before using this drug if:

  • You have a kidney disease
  • You are allergic to other cephalosporins or penicillin
  • You are taking other medication.

Pregnancy: Avoid. It is unknown how this medication may affect your baby. Consult your doctor before using this drug, or if you are planning to fall pregnant.

Breastfeeding: Avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.

Porphyria: Avoid. This medication may cause serious adverse effects. Consult your doctor before use.

Infants and children: This medication is safe for use in children at the recommended dose.

Elderly: Caution is advised in the elderly as adverse effects may be more severe.

Driving and hazardous work: Caution is advised as use of this medication may lead to dizziness, light-headedness and/or sedation. Avoid such activities until you know how this medication affects you.

Alcohol: Avoid concomitant use of alcohol with this medication.

Possible side effects

Side effect


Consult your doctor



Only if severe

In all cases




Stomach cramps



Nausea and vomiting



Rash/hives/itchy skin






Breathing difficulties



Swelling of face/throat






Bloody diarrhoea




Drug interactions


Increased risk of warfarin toxicity

Non-steroidal anti-inflammatory drugs

Increased risk of bleeding


Drugs may counteract each other.

Vancomycin/ aminoglycoside antibiotics

Increased risk of kidney toxicity

Oral contraceptives

Risk of contraceptive failure


Increased levels of antibiotic in body

Overdose action

A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention. Symptoms may include seizures, severe abdominal pain and vomiting.

Recommended dosage

Adults: 1-2 g daily in 2-4 divided doses; Maximum dose: 6g/day

Children: 25-50 mg/kg/day in divided doses; Maximum dose: 100 mg/kg/day or 4 g/day


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