Penicillin is used to treat infections caused by bacteria. They work by killing the bacteria or preventing their growth.

There are several different kinds of penicillin. Each is used to treat different kinds of infections. One kind of penicillin usually may not be used in place of another. In addition, penicillin is used to treat bacterial infections in many different parts of the body. They are sometimes given with other antibacterial medicines (antibiotics). Some of the penicillin may also be used for other problems as determined by your doctor. However, none of the penicillin will work for colds, flu, or other virus infections.

Special precautions

Allergies— tell your doctor if you have ever had any unusual or allergic reaction to any of the penicillin or cephalosporin. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes, or procaine (e.g., Novocain) or other ester-type anesthetics (medicines that cause numbing) if you are receiving penicillin G procaine.

Diet— Make certain your health care professional knows if you are on a low-sodium (low-salt) diet. Some of these medicines contain enough sodium to cause problems in some people.

Pregnancy— Penicillin have not been studied in pregnant women. However, penicillin has been widely used in pregnant women and has not been shown to cause birth defects or other problems in animal studies.

Breast-feeding— Penicillin passes into the breast milk. Even though only small amounts may pass into breast milk, allergic reactions, diarrhea, fungus infections, and skin rash may occur in nursing babies.

Children— much penicillin has been used in children and, in effective doses, is not expected to cause different side effects or problems in children than they do in adults.

Older adults— Penicillin has been used in the elderly and has not been shown to cause different side effects or problems in older people than they do in younger adults.

Other medicines— although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur.

Other medical problems — the presence of other medical problems may affect the use of penicillin. Make sure you tell your doctor if you have any other medical problems, especially:

• Allergy, general (such as asthma, eczema, hay fever, hives), history of—Patients with a history of general allergies may be more likely to have a severe reaction to penicillin

• Bleeding problems, history of—Patients with a history of bleeding problems may be more likely to have bleeding when receiving carbenicillin, piperacillin, or ticarcillin

• Congestive heart failure (CHF) or
• High blood pressure—Large doses of carbenicillin or ticarcillin may make these conditions worse, because these medicines contain a large amount of salt

• Cystic fibrosis—Patients with cystic fibrosis may have an increased chance of fever and skin rash when receiving piperacillin

• Kidney disease—Patients with kidney disease may have an increased chance of side effects

• Mononucleosis (“mono”)—Patients with mononucleosis may have an increased chance of skin rash when receiving ampicillin, bacampicillin, or pivampicillin

• Phenylketonuria—some strength of the amoxicillin chewable tablets contains aspartame, which is changed by the body to phenylalanine, a substance that is harmful to patients with phenylketonuria.

• Stomach or intestinal disease, history of (especially colitis, including colitis caused by antibiotics)—Patients with a history of stomach or intestinal disease may be more likely to develop colitis while taking penicillin

Side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

• Less common
• Fast or irregular breathing;  fever;  joint pain;  lightheadedness or fainting (sudden);  puffiness or swelling around the face;  red, scaly skin;  shortness of breath ;  skin rash, hives, itching 

• Rare
• Abdominal or stomach cramps and pain (severe);  abdominal tenderness;  convulsions (seizures);  decreased amount of urine;  diarrhea (watery and severe), which may also be bloody;  mental depression;  nausea and vomiting;  pain at place of injection;  sore throat and fever ;  unusual bleeding or bruising;  yellow eyes or skin 

• More common
• Diarrhea (mild);  headache;  sore mouth or tongue;  vaginal itching and discharge;  white patches in the mouth and/or on the tongue 

Keep all appointments with your doctor.

Do not let anyone else take your medicines.