Medically reviewed on April 24, 2018.
The Omnipen-N 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 Omnipen-N?
Ampicillin is a penicillin antibiotic that fights bacteria.
Ampicillin may also be used for purposes not listed in this medication guide.
You should not use this medicine if you are allergic to any penicillin antibiotic.
Before taking this medicine
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:
allergies to any foods or drugs;
if you also take a medicine called allopurinol.
This medicine is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.
Ampicillin can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.
How is ampicillin injection given?
Ampicillin is injected into a muscle, or into a vein through an IV. You may be shown how to use an IV at home. Do not self-inject this medicine if you do not understand how to give the injection and properly dispose of used needles, IV tubing, and other items used to inject the medicine.
You may need to mix ampicillin with a liquid (diluent) before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medicine. You should use the injection as soon as possible after mixing it.
Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.
If you are being treated for gonorrhea, your doctor may also have you tested for syphilis, another sexually transmitted disease.
Your doctor may switch you from Omnipen-N to an oral form of this medicine. 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.
If you use this medicine long-term, you may need frequent medical tests.
Ampicillin can cause unusual results with certain lab tests for glucose (sugar) in the urine. Tell any doctor who treats you that you are using this medicine.
Store unmixed ampicillin at room temperature away from moisture and heat.
After mixing your medicine, you will need to use it within a certain number of hours. This will depend on the diluent used, and whether the mixture is stored at room temperature or in a refrigerator. Carefully follow the mixing and storage instructions provided with your medicine. Ask your pharmacist if you have questions.
What happens if I miss a dose?
Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use 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 receiving Omnipen-N?
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.
Omnipen-N 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;
pale skin, easy bruising or bleeding, unusual weakness.
Common side effects may include:
itching or rash;
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 Omnipen-N?
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.
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.
Copyright 1996-2018 Cerner Multum, Inc. Version: 1.01.
More about Omnipen-N (ampicillin)
- Omnipen-N Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Interactions
- Support Group
- En Español
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- Drug class: aminopenicillins