Cloxacillin is a penicillin antibiotic used for the treatment of certain bacterial infections. It is most commonly used to treat infections of the skin, bone, heart valve, blood, and throat.

Your doctor may have suggested this medication for conditions other than the ones listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of cloxacillin ranges from 250 mg to 500 mg 4 times daily taken on an empty stomach (1 hour before or 2 hours after meals). The children's dose depends on the age and weight of the child.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is very important that this medication be taken exactly as prescribed by your doctor. Finish all of this medication, even if you start to feel better. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one.

Nu®-Cloxi is available in strengths of 250 mg and 500 mg capsules, or 125 mg per 5 mL oral solution.

Capsule

250 mg: Type: capsule. Appearance: orange and black. Markings: marked "NU 250." Active ingredient: 500 mg of cloxacillin.

500 mg: Type: capsule. Appearance: orange and black. Markings: marked "NU 500." Active ingredient: 250 mg of cloxacillin.

Nonmedicinal ingredients: amaranth, colloidal silicon dioxide, D&C Yellow No. 10, FD&C Blue No. 1, FD&C Yellow No. 6, stearic acid, talc, and titanium dioxide.

The capsules do not contain gluten or tartrazine.

Oral solution

Type: liquid. Appearance: cherry flavoured liquid. Active ingredient: after reconstitution, each 5 mL liquid contains 125 mg of cloxacillin. Nonmedicinal ingredients: artificial flavouring, FD&C Red No. 40, sodium benzoate, sodium citrate, sodium cyclamate, and sucrose.

The liquid does not contain paraben, sulfite, or tartrazine.

Cloxacillin should not be taken by anyone who:

• is allergic to cloxacillin or any of the ingredients of the medication
• has a serious penicillin allergy

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

More common:

• diarrhea (mild)
• headache
• sore mouth or tongue
• vaginal itching or discharge
• white patches in the mouth or on the tongue

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Rare:

• abdominal or stomach cramps and pain (severe)
• abdominal tenderness
• convulsions
• decreased amount of urine
• depression
• diarrhea (watery and severe; may also be bloody)
• nausea and vomiting
• sore throat and fever
• unusual bleeding or bruising
• yellow eyes or skin

Stop taking the medication and seek immediate medical attention if any of the following occur:

Less common:

• fast or irregular breathing
• fever
• joint pain
• lightheadedness or fainting (sudden)
• puffiness or swelling around the face
• red, scaly skin
• shortness of breath
• skin rash, hives, or itching

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergy: Cloxacillin is a type of penicillin and therefore should not be used by anyone with a serious penicillin allergy. People who have allergies in general should watch carefully for any reaction to cloxacillin when starting a new prescription.

Kidney disease: Patients with kidney disease should be cautious while taking cloxacillin as they may have an increased risk of side effects.

Other infections: Treatment with any penicillin may allow normal fungus or types of bacteria not killed by the antibiotic to overgrow, causing unwanted infections such as yeast infections, which may cause vaginitis.

Stomach problems (especially colitis): Cloxacillin may cause a condition called pseudomembranous colitis (serious diarrhea caused by antibiotics). Therefore, people who experience significant diarrhea after taking this medication should contact their doctor.

Pregnancy: The safety of this medication for use by pregnant women has not been established. It should be used during pregnancy only if clearly needed.

Breast-feeding: Cloxacillin passes into breast milk. This may cause problems (such as diarrhea or oral thrush) for a nursing child. If problems do occur, a decision should be made to either stop breast-feeding or stop the medication, based on the importance of the medication to the mother. The risk of the child developing a penicillin allergy should be kept in mind.

There may be an interaction between cloxacillin and any of the following:

• birth control pills
• methotrexate
• probenecid
• tetracyclines (e.g., minocycline, doxycycline)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.