Generic Name: ampicillin (am pi SIL in)
Brand names: Principen, Totacillin, Omnipen, Omnipen-N, Totacillin-N
What is ampicillin?
Ampicillin is an antibiotic in the penicillin group of drugs. It fights bacteria in your body.
Ampicillin is used to treat many different types of infections caused by bacteria, such as ear infections, bladder infections, pneumonia, gonorrhea, and E. coli or salmonella infection.
Ampicillin may also be used for purposes not listed in this medication guide.
What is the most important information I should know about ampicillin?
Do not use this medication if you are allergic to ampicillin or to any other penicillin antibiotic, such as amoxicillin (Amoxil), carbenicillin (Geocillin), dicloxacillin (Dycill, Dynapen), oxacillin (Bactocill), penicillin (Beepen-VK, Ledercillin VK, Pen-V, Pen-Vee K, Pfizerpen, V-Cillin K, Veetids), and others.
Before using ampicillin, tell your doctor if you are allergic to cephalosporins such as Ceclor, Ceftin, Duricef, Keflex, and others, or if you have asthma, kidney disease, a bleeding or blood clotting disorder, mononucleosis (also called "mono"), or a history of any type of allergy.
Ampicillin can make birth control pills less effective, which may result in pregnancy. Before taking ampicillin, tell your doctor if you use birth control pills. Take this medication for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Ampicillin will not treat a viral infection such as the common cold or flu. Do not share this medication with another person, even if they have the same symptoms you have.
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, stop taking ampicillin and call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.
What should I discuss with my healthcare provider before taking ampicillin?
Do not use this medication if you are allergic to ampicillin or to any other penicillin antibiotic, such as:
amoxicillin (Amoxil, Amoxicot, Biomox, Dispermox, Trimox);
carbenicillin (Geocillin);
dicloxacillin (Dycill, Dynapen);
oxacillin (Bactocill); or
penicillin (Beepen-VK, Ledercillin VK, Pen-V, Pen-Vee K, Pfizerpen, V-Cillin K, Veetids, and others).
To make sure you can safely take ampicillin, tell your doctor if you are allergic to any drugs (especially cephalosporins such as Omnicef, Cefzil, Ceftin, Keflex, and others), or if you have:
asthma;
kidney disease;
a bleeding or blood clotting disorder;
mononucleosis (also called "mono");
a history of diarrhea caused by taking antibiotics; or
a history of any type of allergy.
FDA pregnancy category B. Ampicillin is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Ampicillin can make birth control pills less effective, which may result in pregnancy. Before taking ampicillin, tell your doctor if you use birth control pills. Ampicillin can pass into breast milk and may harm a nursing baby. You should not breast-feed while you are taking ampicillin.
How should I take ampicillin?
Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Take the medicine with a full glass of water. Ampicillin should be taken on an empty stomach, at least 1 hour before or 2 hours after eating a meal.
To be sure this medicine is helping your condition, your blood will need to be tested often. Your liver and kidney function may also need to be tested. Visit your doctor regularly.
If you are being treated for gonorrhea, your doctor may also have you tested for syphilis, another sexually transmitted disease.
Take this medication for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Ampicillin will not treat a viral infection such as the common cold or flu. Do not share this medication with another person, even if they have the same symptoms you have.
This medication 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.
Overdose symptoms may include confusion, behavior changes, a severe skin rash, urinating less than usual, or seizure (black-out or convulsions).
What should I avoid while taking ampicillin?
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, stop taking ampicillin and call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.
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 a serious side effect such as:
fever, sore throat, and headache with a severe blistering, peeling, and red skin rash;
diarrhea that is watery or bloody;
fever, chills, body aches, flu symptoms;
easy bruising or bleeding, unusual weakness;
urinating less than usual or not at all;
agitation, confusion, unusual thoughts or behavior; or
seizure (black-out or convulsions).
Less serious side effects may include
nausea, vomiting, stomach pain;
vaginal itching or discharge;
headache;
swollen, black, or "hairy" tongue; or
thrush (white patches or inside your mouth or throat).
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.
Ampicillin Dosing Information
Usual Adult Dose for Bacterial Endocarditis Prophylaxis:
Low to moderate risk: 2 g IV or IM 30 minutes before procedure.
High risk: Ampicillin 2 g plus gentamicin 1.5 mg/kg IV or IM 30 minutes before procedure. Follow with ampicillin 1 g IV or IM, or amoxicillin 1 g orally, 6 hours after initial dose.
Usual Adult Dose for Bronchitis:
Bacterial exacerbations of chronic bronchitis:
250 to 500 mg orally every 6 hours for 5 to 10 days, depending on the nature and severity of the infection.
Usual Adult Dose for Endocarditis:
Enterococcal:
Ampicillin 2 g IV every 4 hours plus gentamicin 1 mg/kg IV every 8 hours for 4 to 6 weeks.
Usual Adult Dose for Gastroenteritis:
250 to 500 mg orally every 6 hours.
Usual Adult Dose for Intraabdominal Infection:
1 to 2 g IV every 4 to 6 hours in combination with other antibiotics, depending on the nature and severity of the infection.
Duration: 10-14 days.
Usual Adult Dose for Leptospirosis:
Moderate to severe: 0.5 to 1 g intravenously every 6 hours.
Mild: 500 to 750 mg orally every 6 hours.
Usual Adult Dose for Meningitis:
IV:
200 mg/kg/day (up to 12 g/day) IV in equally divided doses every 4 hours, in combination with other parenteral antibiotics.
Intrathecal or intraventricular:
10 to 50 mg/day in addition to IV antibiotics.
Usual Adult Dose for Peritonitis:
CAPD-associated peritonitis: 250 to 500 mg orally twice daily and/or 100 to 125 mg/L exchange intraperitoneally, with or without other antibiotics depending on the nature and severity of the infection.
Secondary: 1 to 2 g IV every 4 to 6 hours in combination with other antibiotics, depending on the nature and severity of the infection.
Duration: 10 to 14 days.
Usual Adult Dose for Pneumonia:
Beta-lactamase negative, penicillin-susceptible: 1 to 2 g IV every 4 to 6 hours, in combination with other antibiotic(s) depending on the nature and severity of the infection.
Usual Adult Dose for Prevention of Perinatal Group B Streptococcal Disease:
As an alternative to penicillin G: 2 g IV as a loading dose, followed by 1 g every 4 hours until delivery.
Usual Adult Dose for Pyelonephritis:
500 mg to 2 g IV or IM every 4 to 6 hours with or without other antibiotics, depending on the nature and severity of the infection.
Duration: 2 to 3 weeks.
Usual Adult Dose for Septicemia:
1 to 2 g IV every 3 to 4 hours, in combination with other antibiotics.
Usual Adult Dose for Shigellosis:
500 mg orally every 6 hours for 5 days
Usual Adult Dose for Skin or Soft Tissue Infection:
250 to 500 mg orally every 6 hours or 1 to 2 g IV every 4 to 6 hours, depending on the nature and severity of the infection.
Usual Adult Dose for Surgical Prophylaxis:
Liver transplant: Ampicillin 1 g plus cefotaxime 1 g IV at induction, then every 6 hours for 48 hours after closure.
Usual Adult Dose for Typhoid Fever:
Severe, fully susceptible: 25 mg/kg IV or IM every 6 hours for 10 to 14 days.
Carrier state: 1.5 g orally or IV with probenecid 500 mg every 6 hours for 6 weeks.
Fluoroquinolones or amoxicillin are considered the drugs of choice.
Usual Adult Dose for Otitis Media:
500 mg orally or 1 to 2 g IV or IM every 6 hours, depending on the nature and severity of the infection.
Usual Adult Dose for Pharyngitis:
500 mg orally or 1 to 2 g IV or IM every 6 hours, depending on the nature and severity of the infection.
Usual Adult Dose for Sinusitis:
500 mg orally or 1 to 2 g IV or IM every 6 hours, depending on the nature and severity of the infection.
Usual Adult Dose for Upper Respiratory Tract Infection:
500 mg orally or 1 to 2 g IV or IM every 6 hours, depending on the nature and severity of the infection.
Usual Adult Dose for Urinary Tract Infection:
Mild, uncomplicated: 250 to 500 mg orally every 6 hours
Severe, complicated: 500 mg to 2 g IV every 4 to 6 hours with or without other antibiotics, depending on the nature and severity of the infection.
Usual Pediatric Dose for Bacterial Endocarditis Prophylaxis:
Low to moderate risk: 50 mg/kg IV or IM 30 minutes before procedure.
High risk: 50 mg/kg plus gentamicin 1.5 mg/kg, both intramuscularly or IV 30 minutes before procedure. Follow with ampicillin 25 mg/kg IV or IM, or amoxicillin 25 mg/kg orally, 6 hours after initial dose.
Usual Pediatric Dose for Meningitis:
Neonates:
2000 g: 50 mg/kg IV every 8 hours.
> 7 days, birthweight > 7 days, birthweight 1200 to 2000 g: 50 mg/kg IV every 8 hours.
> 7 days, birthweight > 2000 g: 50 mg/kg IV every 6 hours.
Infants and children:
50 to 100 mg/kg IV every 6 hours. Maximum dose 12 g/day.
Ampicillin should be given in combination with another antibiotic, depending on the nature of the infection.
Usual Pediatric Dose for Skin or Soft Tissue Infection:
IV: 6.25 to 12.5 mg/kg every 6 hours (maximum 12 g/day).
Oral: 6.25 to 12.5 mg/kg every 6 hours (maximum 2 to 3 g/day).
Usual Pediatric Dose for Upper Respiratory Tract Infection:
IV: 6.25 to 12.5 mg/kg every 6 hours (maximum 12 g/day).
Oral: 6.25 to 12.5 mg/kg every 6 hours (maximum 2 to 3 g/day).
Usual Pediatric Dose for Surgical Prophylaxis:
Liver transplant: Ampicillin 50 mg/kg plus cefotaxime 50 mg/kg at induction and every 6 hours for 48 hours after closure.
What other drugs will affect ampicillin?
Tell your doctor about all other medicines you use, especially:
allopurinol (Zyloprim);
methotrexate (Rheumatrex, Trexall);
probenecid (Benemid);
a sulfa drug (such as Bactrim or Septra); or
a tetracycline antibiotic such as demeclocycline (Declomycin), doxycycline (Adoxa, Doryx, Oracea, Vibramycin), minocycline (Dynacin, Minocin, Solodyn, Vectrin), or tetracycline (Brodspec, Panmycin, Sumycin, Tetracap).
This list is not complete and there may be other drugs that can interact with ampicillin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.
More ampicillin resources
- Ampicillin Side Effects (in more detail)
- Ampicillin Use in Pregnancy & Breastfeeding
- Drug Images
- Ampicillin Drug Interactions
- Ampicillin Support Group
- 3 Reviews for Ampicillin - Add your own review/rating
- Ampicillin Prescribing Information (FDA)
- Ampicillin Professional Patient Advice (Wolters Kluwer)
- Ampicillin Monograph (AHFS DI)
- Ampicillin MedFacts Consumer Leaflet (Wolters Kluwer)
- Ampicillin Sodium and Sulbactam Sodium Monograph (AHFS DI)
- Principen Advanced Consumer (Micromedex) - Includes Dosage Information
Compare ampicillin with other medications
- Bacterial Endocarditis Prevention
- Bronchitis
- Endocarditis
- Gastroenteritis
- Intraabdominal Infection
- Kidney Infections
- Leptospirosis
- Meningitis
- Otitis Media
- Peritonitis
- Pharyngitis
- Pneumonia
- Prevention of Perinatal Group B Streptococcal Disease
- Septicemia
- Shigellosis
- Sinusitis
- Skin Infection
- Surgical Prophylaxis
- Typhoid Fever
- Upper Respiratory Tract Infection
- Urinary Tract Infection
Where can I get more information?
- Your pharmacist can provide more information about ampicillin.
See also: ampicillin side effects (in more detail)
