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Generic Name: ampicillin (am pi SIL in)
Brand Name: Principen

What is Principen (ampicillin)?

Ampicillin is a penicillin antibiotic that fights bacteria.

Ampicillin is used to treat or prevent many different types of infections such as bladder infections, pneumonia, gonorrhea, meningitis, or infections of the stomach or intestines.

Ampicillin may also be used for purposes not listed in this medication guide.

What is the most important information I should know about Principen (ampicillin)?

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Slideshow: Is it Safe to Give Human Medicine to Pets?

Always get your pet's drug and dose recommendation from the veterinarian.

What should I discuss with my healthcare provider before taking Principen (ampicillin)?

You should not use this medicine if you are allergic to ampicillin or to any other penicillin antibiotic, such as amoxicillin (Amoxil, Augmentin, Moxatag, and others), carbenicillin, dicloxacillin, or penicillin.

To make sure ampicillin is safe for you, tell your doctor if you have:

  • asthma;

  • kidney disease;

  • a history of diarrhea caused by taking antibiotics; or

  • if you are allergic to a cephalosporin antibiotic.

This medicine is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Ampicillin can make birth control pills less effective. Ask your doctor about using non hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy.

Ampicillin can pass into breast milk and may harm a nursing baby. You should not breast-feed while using this medicine.

How should I take Principen (ampicillin)?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take this medicine with a full glass of water.

Take ampicillin on an empty stomach, at least 30 minutes before or 2 hours after a meal.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Do not share this medicine with another person, even if they have the same symptoms you have.

If you are being treated for gonorrhea, your doctor may also have you tested for syphilis, another sexually transmitted disease.

Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Ampicillin will not treat a viral infection such as the flu or a common cold.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using ampicillin.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Principen (ampicillin)?

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

Principen (ampicillin) side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • severe stomach pain, diarrhea that is watery or bloody;

  • fever, chills, body aches, flu symptoms; or

  • easy bruising or bleeding, unusual weakness.

Common side effects may include:

  • nausea, vomiting, stomach pain;

  • swollen, black, or "hairy" tongue; or

  • vaginal itching or discharge.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect Principen (ampicillin)?

Other drugs may interact with ampicillin, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Where can I get more information?

  • Your pharmacist can provide more information about ampicillin.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 7.01. Revision Date: 2015-02-26, 8:02:50 AM.