What is cefalexin used for?

Cefalexin is an antibiotic that can kill certain types of bacteria that cause infections. To get cefalexin, you must have a prescription written for you by a doctor.

Cefalexin is used to treat bacterial infections in various parts of the body. This includes infections of your airways (chest and lungs), throat, sinuses, ears, skin and soft tissue, kidneys and bladder.

How does cefalexin work?

Cefalexin works by killing different bacteria that cause an infection. Always finish the full course of cefalexin as prescribed by your doctor to get rid of the infection. If you don’t, you risk the infection returning.

What forms of cefalexin are available?

Cefalexin is the name of the active ingredient. It is available in many different brands, which have different:

• names
• appearances (size, shape or colour)
• forms (capsules and suspension)
• packaging

No matter which brand you are prescribed, cefalexin works in the same way to treat your infection.

What are the possible side effects of cefalexin?

Cefalexin helps to treat most infections, although some strains of bacteria are resistant to it. Side effects are usually rare.

The more common side effects include:

• oral or vaginal thrush (a type of yeast infection in the mouth or vagina)
• diarrhoea
• nausea
• vomiting
• dizziness
• tiredness or weakness
• abdominal pain
• headache

Serious side effects are very rare. See your doctor immediately or go to the emergency department of your nearest hospital if you experience sudden signs of allergy such as:

• rash, itching or hives on your skin
• swelling of the face, lips, tongue or other part of the body
• difficulty breathing, shortness of breath or wheezing

You should also tell your doctor immediately if you develop severe stomach pain or severe watery or bloody diarrhoea along with a fever, especially if this happens several weeks after stopping cefalexin treatment.

This is not a full list of side effects. For more information about the risks of side effects, read the Consumer Medicines Information (CMI) on cefalexin or speak to your doctor or pharmacist.

Note that cefalexin is similar in some ways to penicillin. Don’t take cefalexin if you’ve had a serious allergic reaction to penicillin.

When should I see my doctor?

Speak to your doctor if you:

• experience side effects that trouble you
• have signs of an allergic reaction
• have a health condition or are taking medication that may affect how your body reacts to cefalexin
• become pregnant or start breastfeeding

See the CMI for full details about when to speak with your doctor before or after you have started taking cefalexin.

Are there alternatives to cefalexin?

If you can’t take cefalexin, there are other antibiotics that you can use. 

Resources and support

Asking about your treatment or medicine is important to help you understand your options. Read our guide on important questions to ask your pharmacist or doctor before taking a medicine.

You can also visit healthdirect's list of medicines that contain cefalexin to read the CMI for the brand of cefalexin you have been prescribed.