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Principen

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

Medically reviewed on Feb 26, 2018

The Principen brand name has been discontinued in the U.S. If generic versions of this product have been approved by the FDA, there may be generic equivalents available.

What is Principen?

Principen is a penicillin antibiotic that fights bacteria.

Principen 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.

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

Important Information

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.

Before taking this medicine

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

To make sure Principen 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.

Principen 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?

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 Principen 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. Principen 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 Principen.

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?

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 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.

What other drugs will affect Principen?

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.

Further information

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.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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