Cloxacillin is used in the treatment of infections caused by gram-positive organisms. It is particularly effective against infections caused by penicillinase-producing staphylococci. These infections include:

Skin and soft tissue infections: boils, abscesses, carbuncles, furunculosis, cellulitis, infected wounds, infected burns, protection for skin grafts, and various skin infections such as ulcers, eczema, and acne.

Respiratory, ear, nose, and throat infections: pneumonia, lung abscess, empyema, sinusitis, pharyngitis, tonsillitis, cough, otitis media, and otitis externa.

Other infections caused by cloxacillin-sensitive organisms: osteomyelitis, endocarditis, enteritis, urinary tract infections, and septicemia.

Usual adult dose-
Oral: 500 mg four times daily, half to one hour before meals.
As injection:

• Intramuscular injection: 250 mg every 4 to 6 hours.
• Intravenous injection: 500 mg every 4 to 6 hours. The above dose may be doubled if necessary.
• Intrapleural injection: 500 mg once daily.
• Intra-articular injection: 500 mg once daily.

Usual pediatric dose-
Oral: 2 to 10 years – half of the adult dose. Under 2 years – one-fourth of the adult dose.
As injection:

• Intramuscular injection: Dissolve 250 mg with 1.5 ml or 500 mg with 2 ml Water for Injection.
• Intravenous injection: Dissolve 500 mg with 5–10 ml Water for Injection. Then administer slowly over 3 to 4 minutes or give as infusion or administer through drip tube slowly over 3 to 4 minutes after proper dilution.
• Intrapleural injection: Dissolve 500 mg with 5 to 10 ml Water for Injection and administer.
• Intra-articular injection: Dissolve 500 mg with not more than 5 ml Water for Injection or dissolve with 0.5% Lignocaine Hydrochloride solution and administer.

Cloxacillin should not be used in patients who are hypersensitive to penicillin.

The side effects of cloxacillin are similar to those of other penicillins and are usually mild and temporary. These include gastrointestinal disturbances such as indigestion and allergic reactions like rash or urticaria. If such symptoms occur, the medication should be discontinued as per medical advice.

Cloxacillin should be used with caution in patients with a history of allergies. It should not be administered as a subconjunctival injection or as eye drops.

After reconstitution, cloxacillin syrup or suspension should be stored in a cool place, preferably refrigerated. The prepared suspension should be used within 5 days at room temperature or within 7 days if refrigerated. The injection solution should be used within 30 minutes after preparation. However, the dry powder form of cloxacillin remains stable for up to 24 hours at room temperature (25°C).

Cloxacillin can be mixed with most commonly used intravenous fluids, but it should not be mixed with certain amino acid solutions (such as protein hydrolysates).

Penicillinase-resistant penicillins

All dosage forms of cloxacillin should be stored in a cool and dry place. Injection vials should be kept below 25°C.