As mentioned, dicloxacillin is a penicillin antibiotic. Penicillins are part of a larger group of medications known as beta-lactam antibiotics, which are named after the ring-like "lactam" structure of these drugs. Dicloxacillin works by stopping bacteria from making cell walls, which eventually causes the bacteria to die.
More specifically, dicloxacillin is a penicillinase-resistant penicillin. Some bacteria produce penicillinase, an enzyme that destroys the beta-lactam structure of penicillin, making it and other similar antibiotics ineffective for treating infections due to such bacteria. Dicloxacillin is resistant to penicillinase.
However, such bacteria (notably, MRSA) have developed resistance against dicloxacillin and other penicillinase-resistant penicillins. Dicloxacillin is ineffective against MRSA.
Dicloxacillin is approved for use in children. Because the dicloxacillin dosage used in children is based on weight, it is important that your healthcare provider has an accurate weight for your child. It may be best to actually weigh the child, as a child's weight frequently changes.
On occasion, your healthcare provider may recommend this medication for something other than treating the infections discussed in this article. This is known as an "off-label" use. Using dicloxacillin to prevent any type of infection would be an off-label use.