Penicillins : Side Effects and Risks

by Food and Drug Administration (FDA)

(Page 2 of 2)

Although most penicillins are safe for the majority of people, some people may experience side effects.

The most serious of these is anaphylaxis, a severe allergic reaction that can cause skin rash, hives, itching, difficulty breathing, shock, and unconsciousness. An early sign of anaphylaxis is a feeling of warmth and flushing. If any of these occurs, the medicine should be stopped and emergency help sought immediately. In some cases, these symptoms can pro-gress to death.

Also, if you notice blood in your urine, have large amounts of light-colored urine, or experience swelling of the face or ankles, difficulty breathing, or unusual tiredness or weakness, consult your doctor immediately.

Certain penicillins — amoxicillin and clavulanate, azlocillin, mezlocillin, oxacillin, or piperacillin — may occasionally cause dark or amber urine, pale stools, stomach pain, or yellow eyes or skin. If you experience any of these symptoms, check with your doctor immediately.

On rare occasions some types of penicillin may cause severe abdominal or stomach cramps, pain, or bloating or severe or bloody diarrhea. If diarrhea is severe and watery, or if it has blood in it, check with your doctor immediately.

Other rare side effects include fever, increased thirst, severe nausea or vomiting, unusual tiredness or weakness, weight loss, seizures, or unusual bleeding or bruising. If any of these occur (and they may not occur until several weeks after you stop taking the medicine), check with your doctor immediately.

Common, less serious, side effects that some people experience include mild diarrhea and mild nausea or vomiting. These usually don't require medication, and a doctor need not be consulted unless they continue or are bothersome.

Diarrhea medicine containing kaolin (such as Kaopectate or Donnagel) or attapulgite (such as Diasorb) may be taken to relieve mild diarrhea without checking with your doctor. However, some ingredients in diarrhea medicine, such as lactose, may make diarrhea worse, so read labels carefully.

Occasionally, certain types of penicillin may cause the tongue to darken or discolor. This condition is temporary and will go away when the medicine is stopped.

Because penicillin can change the results of some medical tests, tell lab personnel if you are taking penicillin. Some types of penicillin may cause false test results on some urine sugar tests. Persons with diabetes taking penicillin should not change their diets or the dose of their diabetes medicine based on these tests before checking with their doctors.

Before Taking This Medicine

If you have ever had an allergic reaction to penicillin, be sure to let your doctor know, preferably at your first visit, even if you do not then have an infection.

Your doctor should also be told if you have a general history of allergy, such as asthma, eczema, hay fever or hives; if you have ever had a reaction to Novocain (procaine) or other medicines that cause numbing; or if you are on a special diet or are allergic to any substances such as foods, preservatives or dyes.

Also, before taking penicillin, be sure to let your doctor know:

Fif you are pregnant or plan to become pregnant. Although penicillins have not been shown to cause birth defects or other problems in animals, studies have not been done in humans. Penicillin should be used during pregnancy only if clearly needed.

Ff you are breast-feeding. Most penicillins pass into the breast milk in small amounts and may cause allergic reactions, diarrhea, fungal infections, and skin rash in babies.

Ff you have a history of bleeding problems, kidney disease, liver disease, infectious mononucleosis, or stomach or intestinal disease, especially colitis or enteritis.

Ff you are taking any other prescription or nonprescription medicine.

Women on birth control pills containing estrogen should use an additional type of birth control when taking ampicillin, bacampicillin, or penicillin V because the effect of birth control pills may be diminished.

Types of Penicillin

amdinocillin
amoxicillin
amoxicillin and clavulanate
ampicillin
ampicillin and sulbactam
azlocillin
bacampicillin
carbenicillin
cloxacillin
cyclacillin
dicloxacillin
methicillin
mezlocillin
nafcillin
oxacillin
penicillin G
penicillin V
piperacillin
ticarcillin
ticarcillin and clavulanate

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.