Cephalosporins are used to treat infections in different parts of the body—the ears, nose, throat, lungs, sinuses, and skin, for example. Physicians may prescribe these drugs to treat pneumonia, strep throat, staph infections, tonsillitis, bronchitis, and gonorrhea. These drugs will not work for colds, flu, and other infections caused by viruses.

Cephalosporins are a newer class of antibiotics and often are seen as an alternative to penicillin for many patients. Clinical studies continue to compare this class of antibiotics to penicillin in combating various infections. For example, a 2004 study showed that cephalosporins are three times more effective than penicillin for treating bacterial throat infections, such as strep throat, in children. The authors recommended cephalosporin drugs as the first choices for pediatricians.

Examples of cephalosporins are cefaclor (Ceclor), cefadroxil (Duricef), cefazolin (Ancef, Kefzol, Zolicef), cefixime, (Suprax), cefoxitin (Mefoxin), cefprozil (Cefzil), ceftazidime (Ceptaz, Fortaz, Tazicef, Tazideme), cefuroxime (Ceftin) and cephalexin (Keflex). These medicines are available only with a physician's prescription. They are sold in tablet, capsule, liquid, and injectable forms.

The recommended dosage depends on the type of cephalosporin. The physician who prescribed the drug or the pharmacist who filled the prescription can recommend the correct dosage.

Cephalosporins always should be taken exactly as directed by the physician. Patients never should take larger, smaller, more frequent, or less frequent doses. The drug should be taken for exactly as long as directed, no more and no less. Patients should not save some doses of the drug to take for future infections. The medicine may not be right for other kinds of infections, even if the symptoms are the same. In addition, patients should take all of the medicine to treat the infection for which it was prescribed. The infection may not clear up completely if too little medicine is taken. Taking this medicine for too long, on the other hand, may open the door to new infections that do not respond to the drug.

Some cephalosporins work best when taken on an empty stomach. Others should be taken after meals. The physician who prescribed the medicine or the pharmacist who filled the prescription can provide instructions on how to take the medicine.

Certain cephalosporins should not be combined with alcohol or with medicines that contain alcohol. Abdominal or stomach cramps, nausea, vomiting, facial flushing, and other symptoms may result within 15–30 minutes and may last for several hours. Alcoholic beverages or other medicines that contain alcohol should not be used while being treated with cephalosporins and for several days after treatment ends.

People with certain medical conditions or who are taking certain other medicines can have problems if they take cephalosporins. Before taking these drugs, the physician should be told about any of these conditions:

Severe allergic reactions to this medicine may occur. Anyone who is allergic to cephalosporins of any kind should not take other cephalosporins. Anyone who is allergic to penicillin should check with a physician before taking any cephalosporin. The physician should also be told about allergies to foods, dyes, preservatives, or other substances.

Some cephalosporins may cause false positive results on urine sugar tests for diabetes. People with diabetes should check with their physicians to see if they need to adjust their medication or their diets.

Oral suspensions of cefprozil contain phenylalanine. People with phenylketonuria (PKU) should consult a physician before taking this medicine.

Women who are pregnant or who may become pregnant should check with their physicians before using cephalosporins.

Cephalosporins may pass into breast milk and may affect nursing babies. Women who are breastfeeding and who need to take this medicine should check with their physicians. They may need to stop breastfeeding until treatment is finished.

Before using cephalosporins, people with any of these medical problems should make sure their physicians are aware of their conditions:

• History of stomach or intestinal problems, especially colitis. Cephalosporins may cause colitis in some people.
• Kidney problems. The dose of cephalosporin may need to be lowered.
• Bleeding problems. Cephalosporins may increase the chance of bleeding in people with a history of bleeding problems.
• Liver disease. The dose of cephalosporin may need to be lowered.

Taking cephalosporins with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

Medical attention should be sought immediately if any of these symptoms develop while taking cephalosporins:

• shortness of breath
• pounding heartbeat
• skin rash or hives
• severe cramps or pain in the stomach or abdomen
• fever
• Severe watery or bloody diarrhea (may occur up to several weeks after stopping the drug)
• unusual bleeding or bruising.

Other rare side effects may occur. Anyone who has unusual symptoms during or after treatment with cephalosporins should get in touch with his or her physician

Some cephalosporins cause diarrhea. Certain diarrhea medicines, such as diphenoxylate-atropine (Lomotil), may make the problem worse. A physician should be consulted before taking any medicine for diarrhea caused by taking cephalosporins.

Birth control pills may not work properly when taken at the same time as cephalosporins. To prevent pregnancy, other methods of birth control should be used in addition to the pills while taking cephalosporins.

Taking cephalosporins with certain other drugs may increase the risk of excess bleeding. Among the drugs that may have this effect when taken with cephalosporins are:

• blood thinning drugs (anticoagulants) such as warfarin (Coumadin)
• blood viscosity reducing medicines such as pentoxifylline (Trental)
• the antiseizure medicines divalproex (Depakote) and valproic acid (Depakene)

Cephalosporins may also interact with other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes cephalosporins should let the physician know all other medicines he or she is taking.