How does it work?

Keflex tablets, capsules and oral suspension contain the active ingredient cefalexin, which is a type of medicine called an antibiotic. (NB. Cefalexin is also available without a brand name, ie as the generic medicine.) Cefalexin is a type of antibiotic called a cephalosporin. These antibiotics are related to penicillin. Cefalexin is used to treat infections wih bacteria.

Cefalexin works by interfering with the ability of bacteria to form cell walls. The cell walls of bacteria are vital for their survival. They keep unwanted substances from entering their cells and stop the contents of their cells from leaking out. Cefalexin impairs the bonds that hold the bacterial cell wall together. This allows holes to appear in the cell walls and kills the bacteria.

Cefalexin is a broad-spectrum antibiotic that kills a wide variety of bacteria that cause a wide variety of commonly-occuring infections. Cefalexin is given by mouth to treat infections of the upper and lower airways, ears, skin and soft tissue. It may also be used to treat urinary tract infections, certain sexually-transmitted infections, bone and joint infections and dental infections.

To make sure the bacteria causing an infection are susceptible to cefalexin your doctor may take a tissue sample, for example a swab from the throat or skin, or a urine or blood sample.

What is it used for?

• Bacterial infections of the lungs and airways (respiratory tract).
• Bacterial infections of the middle ear (otitis media).
• Bacterial infections of the skin or soft tissue.
• Bacterial infections of bones and joints.
• Bacterial infections of the urinary tract, including chronic prostatitis.
• Bacterial infections of the genitals.
• Bacterial infections of the teeth or gums.

How do I take it?

• The dose of this medicine and how long it needs to be taken for depends on the type of infection you have, your age and your kidney function. Follow the instructions given by your doctor. These will be printed on the dispensing label that your pharmacist has put on the packet of medicine.
• Cefalexin can be taken either with or without food. You should try to space the doses evenly throughout the day.
• The tablets and capsules should be swallowed with liquid.
• Bottles of suspension should be shaken before measuring out a dose. Only use the measuring spoon provided with the suspension. You should not use a regular teaspoon or tablespoon to take the medicine, as this will not give an accurate dose.
• Keflex suspension should be stored in a cool place (6°C-15°C) or in a refrigerator (2°C-8°C). Any suspension remaining after 10 days should be disposed of, preferably by returning it to your pharmacist.
• Unless your doctor tells you otherwise, it is important that you finish the prescribed course of this antibiotic medicine, even if you feel better or it seems the infection has cleared up. Stopping the course early increases the chance that the infection will come back and that the bacteria will grow resistant to the antibiotic.

Warning!

• Broad-spectrum antibiotics can sometimes cause inflammation of the bowel (colitis). For this reason, if you get diarrhoea that becomes severe or persistent or contains blood or mucus, either during or after treatment with this medicine, you should consult your doctor immediately.

Use with caution in

• Decreased kidney function.
• Allergy to penicillin-type antibiotics.

Not to be used in

• Allergy to other cephalosporin-type antibiotics.
• People with a history of an immediate severe allergic reaction to a penicillin-type antibiotic.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• This medicine is not known to be harmful when used by pregnant women. However, as with all medicines, it should be used with caution during pregnancy and only when considered essential by your doctor, particularly during the first trimester. Seek medical advice from your doctor.
• This medicine passes into breast milk. It should be used with caution in breastfeeding mothers and only if the expected benefit to the mother is greater than any possible risk to the nursing infant. Seek medical advice from your doctor.

Label warnings

• Take at regular intervals. Complete the prescribed course unless otherwise directed.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

• Diarrhoea.
• Nausea and vomiting.
• Abdominal pain.
• Indigestion.
• Headache.
• Dizziness.
• Rash or itching.
• Allergic reactions to active ingredient.
• Bowel infection resulting in inflammation of the bowel lining (pseudomembranous colitis - see warning section above).
• Agitation.
• Confusion.
• Pain in the joints.
• Disturbance in the levels of blood cells in the blood.
• Liver or kidney disorders.

Prolonged treatment with antibiotics can sometimes cause overgrowth of other organisms that are not susceptible to the antibiotic, for example fungi or yeasts such as Candida. This may sometimes cause infections such as thrush. Tell your doctor if you think you have developed a new infection during or after taking this antibiotic.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.

In the past, women using hormonal contraception such as the pill or patch would be advised to use an extra method of contraception (eg condoms) while taking an antibiotic like this one and for seven days after finishing the course. However, this advice has now changed. You no longer need to use an extra method of contraception with the pill, patch or vaginal ring while you take a course of antibiotics. This change in advice comes because to date there is no evidence to prove that antibiotics (other than rifampicin or rifabutin) affect these contraceptives. This is the latest guidance from the Faculty of Sexual & Reproductive Healthcare.

However, if you are taking the contraceptive pill and experience vomiting or diarrhoea as a result of taking this antibiotic, you should follow the instructions for vomiting and diarrhoea described in the leaflet provided with your pills.

Broad spectrum antibiotics such as cefalexin may enhance the effect of anticoagulant medicines to prevent blood clots, such as warfarin. If you are taking warfarin your doctor may want you to have your blood clotting time (INR) checked more frequently while taking this antibiotic.

Oral typhoid vaccine (Vivotif) should not be taken until at least three days after you have finished a course of this antibiotic, because the antibiotic could make this vaccine less effective.