Hopkins ABX Guide

Nafcillin Antibiotic

What is Nafcillin and Why It is Used?

Nafcillin is an antibiotic from the penicillin group of antibiotics. It is a narrow-spectrum, beta-lactamase resistant type of penicillin which means that it works against bacteria that are naturally resistant or have developed resistance to other beta-lactam penicillins. This antibiotic is very similar to oxicillin and methicillin that belong to the same type of penicillins. It works by inhibiting bacterial growth.

The medication is used to treat all sorts of bacterial infections that are caused by Gram-positive species but it is most often used for infections caused by Staphylococcus species that don’t respond to other penicillins. Unfortunately, it doesn’t work against methicillin-resistant Staphylococcus aureus (MRSA) which has developed resistance to all beta-lactam penicillins.

How is Nafcillin Taken/Administered?

Nafcillin is usually administered by a doctor in the form of injection in a hospital or clinic. Dosage and duration are set based on the severity, type and location of the infection as well as patient’s health. The antibiotic is usually administered every four to six hours. Nafcillin is also available in the form of oral capsules and intravenous solution.

No matter in which form it is taken/administered, it is crucial to complete the entire course of treatment to prevent recurrence of the infection and help tackle the problem of antibiotic resistance. Improper use enables bacteria to adjust to the effects of antibiotics and eventually, develop resistance and make particular antibiotics ineffective.

Side Effects of Nafcillin

This medication can cause all sorts of side effects including very severe and potentially life-threatening reactions. Fortunately, these are relatively rare and the most common side effects are not dangerous. During - and in some cases after - nafcillin therapy it is possible to experience diarrhoea which can in rare cases lead to a serious intestinal infection with bacterium Clostridium difficile, nausea, vomiting and stomach pain, while prolonged use can cause thrush (yeast infection in the mouth) and vaginal yeast infection. Those who receive the antibiotic as an injection may also develop redness and pain at the site of the injection.

As mentioned earlier, serious, life-threatening side effects are rare. Serious reactions that require immediate medical attention include joint/muscle pain, changes in the amount or/and colour of urine, extreme weakness, easy bruising, fever and confusion. The same counts for a rash, swelling in the face or mouth, or difficulties breathing which can be the early symptoms of a potentially very serious allergic reaction.