When treating or preventing bacterial infections with cefazolin, the dosage will be calculated based on your age, weight, and various other factors. This prescription antibiotic comes as an injection that is given intravenously or as an intramuscular injection. For serious infections, the drug is usually given intravenously; less serious infections usually are treated with intramuscular injections.
The dosage of cefazolin (Ancef®) your healthcare provider recommends will vary, depending on a number of factors, such as:
- Your age
- Your weight
- The type and severity of the infection being treated
- How well your kidneys are functioning.
- Other medical conditions you may have.
As is always the case, do not adjust your dosage unless your healthcare provider specifically tells you to do so.
Although the recommended dosage for cefazolin varies, the usual amount for adults typically ranges from 0.5 grams (500 mg), up to 1.5 grams (1500 mg), every 6 to 12 hours, given either intravenously (by IV) or by injection into a muscle (IM injection). In general, the more serious the infection, the higher and more frequent the amount. Also, for more serious infections, cefazolin should be given by IV; IM injections are typically used for less serious infections.
For children, the dosage is calculated based on the child's weight, the severity of the infection, and the child's kidney function.
For preventing surgical infections in adults, the standard amount is a single dose of cefazolin 1 gram given by IV 30 to 90 minutes before the first incision. For long surgeries that last two hours or more, a second dose may be given during surgery. After surgery, doses of 0.5 grams to 1 gram every six to eight hours are continued for one to five days.