Nafcillin Sodium

You should not use this medication if you are allergic to nafcillin or to any other penicillin antibiotic, such as amoxicillin (Amoxil), ampicillin (Omnipen, Principen), oxacillin (Bactocill), penicillin (Beepen-VK, Ledercillin VK, Pen-V, Pen-Vee K, Pfizerpen, V-Cillin K, Veetids), and others.

Before using nafcillin, tell your doctor if you are allergic to cephalosporins such as Ceftin, Cefzil, Keflex, Omnicef, and others, or if you have asthma, liver or kidney disease, or a history of any type of allergy.

Use this medication for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Nafcillin is usually given for up to 2 days after lab tests show that the infection has cleared.

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, stop taking nafcillin and call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.