Ampicillin is used to treat a wide variety of bacterial infections. It is a penicillin-type antibiotic. Ampicillin works by targeting the bacterial cell wall which inhibits bacterial cell growth and leads to bacterial cell death.
Know the basics
What is ampicillin used for?
- Gastrointestinal (GI) tract infections
- Genitourinary (GU) tract infections
- Respiratory tract infections
- Sepsis
- Meningitis
- Endocarditis
Antibiotics only treat bacterial infections. It will not work for viral infections (e.g. common cold, flu). Unnecessary use or overuse of any antibiotic can lead to its decreased effectiveness.
How should I take ampicillin?
As an oral dosage form, swallow the dose whole without chewing or crushing it. It should be taken on an empty stomach or before meals. If it is a powder for suspension, you need to reconstitute it by mixing the powder with drinking water. Follow the directions on the packaging.
For intravenous (IV) injections, it should be administered by a licensed healthcare professional.
How do I store ampicillin?
This product is best stored at controlled room temperature away from direct light and moisture. If a suspension is reconstituted, store it in the refrigerator (2-8°C ) for up to 14 days. To prevent drug damage, you should not store it in the bathroom or the freezer.
There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.
You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.
Know the precautions & warnings
What should I know before using ampicillin?
Before using this drug, tell your doctor if you are/have:
- Pregnant or breastfeeding.
- Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
- An allergy to any of the ingredients of this product or other penicillin-type antibiotics.
- Any other illnesses, disorders, or medical conditions.
Is it safe to take ampicillin during pregnancy or breast-feeding?
Unfortunately, there isn’t enough information about the safety of using this drug during pregnancy and breastfeeding. However, it is likely safe to take. Please always consult with your doctor to weigh the potential benefits and risks before taking any medication.
This medication is pregnancy risk category B according to the US Food and Drug Administration (FDA).
FDA pregnancy risk category reference below:
- A=No risk
- B=No risk in some studies
- C=There may be some risk
- D=Positive evidence of risk
- X=Contraindicated
- N=Unknown
Know the side effects
What are the side effects of ampicillin?
Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:
- Allergic reaction
- Diarrhea
- Nausea, vomiting
- Mouth sores
- Black, “hairy’ tongue
- SJS/TEN
- Fever
- Joint pain
- Anemia
- Prolonged bleeding
- Jaundice
- Abnormal liver enzymes
Seek consult immediately if you experience:
However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.
Know the interactions
What drugs may interact with ampicillin?
This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects.
To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist.
Drugs with known interactions:
- Dextrose solutions (e.g. D5w)
- Lactated ringer solution
- Fat emulsion 10%
- Hetastarch 6%
- Allopurinol
- Aminoglycosides
- Atenolol
- Live vaccines (e.g. BCG, cholera, typhoid)
- Chloroquine
- Dichlorphenamide
- Lactobacillus and estriol
- Lanthanum
- Methotrexate
- Mycophenolate
- Oral contraceptives
- Probenecid
- Sodium picosulfate
- Tetracyclines
- Warfarin
If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.
Does food or alcohol interact with ampicillin?
Ampicillin may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. It is best to take this medication on an empty stomach, either 1-2 hours before a meal or 2-3 hours after a meal. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.
What health conditions may interact with ampicillin?
This drug may interact with underlying conditions. This interaction may worsen your health condition or alter the way the drug works. Therefore, it is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:
- Asthma
- Kidney disease
- A bleeding or blood clotting disorder
- Mononucleosis
- A history of diarrhea caused by taking antibiotics
Understand the dosage
The information provided is not a substitute for medical advice. Always consult your doctor or pharmacist before using this medication.
What is the dose for an adult?
Bacterial Infection:
250 to 500 mg orally every 6 hours.
Endocarditis:
Ampicillin 2 g intravenous every 4 hours plus gentamicin or streptomycin (if gentamicin resistant). For prophylaxis, give 2 g intravenous or intramuscular as a single dose 30 to 60 minutes before procedure.
Meningitis:
200 mg/kg/day intravenous in equally divided doses every 4 hours, in combination with other parenteral antibiotics.
Intrathecal or intraventricular: 10 to 50 mg/day in addition to intravenous antibiotics.
Septicemia:
intravenous 150 to 200 mg/kg/day.
Gastroenteritis and intraabdominal infections:
500 mg orally or intravenous or intramuscular every 6 hours.
Skin or Soft Tissue Infection:
250 to 500 mg intravenous or intramuscular every 6 hours.
Pharyngitis:
250 to 500 mg intravenous or intramuscular every 6 hours. Or 250 mg orally every 6 hours.
Sinusitis:
250 to 500 mg intravenous or intramuscular every 6 hours. Or 250 mg orally every 6 hours.
Respiratory Tract Infection:
250 to 500 mg intravenous or intramuscular every 6 hours. Or 250 mg orally every 6 hours.
Urinary Tract Infection:
500 mg orally or intravenous or intramuscular every 6 hours.
Shigellosis or Typhoid Fever:
500 mg orally or intravenous or intramuscular every 6 hours.
Prevention of Perinatal Group B Streptococcal Disease:
2 g intravenous initial dose, then 1 g intravenous every 4 hours until delivery.
Surgical Prophylaxis:
Liver transplant: Ampicillin 1 g intravenous plus cefotaxime 1 g intravenous at induction of anesthesia, then every 6 hours during procedure and for 48 hours after final surgical closure.
Leptospirosis:
Mild: 500 to 750 mg orally every 6 hours
Moderate to severe: 0.5 to 1 g intravenous every 6 hours.
Otitis Media:
500 mg orally or 1 to 2 g intravenous or intramuscular every 6 hours, depending on the nature and severity of the infection.
What is the dose for a child?
Bacterial Infection:
Neonates:
7 days or less, 2000 g or less: 50 mg/kg intravenous or intramuscular every 12 hours.
7 days or less, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 8 hours.
8 to 28 days, 2000 g or less: 50 mg/kg intravenous or intramuscular every 8 hours.
8 to 28 days, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 6 hours.
1 month or older:
Mild to moderate infections:
Parenteral: 25 to 37.5 mg/kg intravenous or intramuscular every 6 hours
Oral: 12.5 to 25 mg/kg orally every 6 hours
Maximum dose: 4 g/day.
Bacteremia:
Neonates:
7 days or younger, 2000 g or less: 100 mg/kg intravenous or intramuscular every 12 hours.
7 days or younger, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 8 hours or 100 mg/kg intravenous or intramuscular every 12 hours.
8 to 28 days, 2000 g or less: 50 mg/kg intravenous or intramuscular every 8 hours.
8 to 28 days, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 6 hours.
Septicemia:
Neonates:
7 days or younger, 2000 g or less: 100 mg/kg intravenous or intramuscular every 12 hours
7 days or younger, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 8 hours or 100 mg/kg intravenous or intramuscular every 12 hours
8 to 28 days, 2000 g or less: 50 mg/kg intravenous or intramuscular every 8 hours
8 to 28 days, greater than 2000 g: 50 mg/kg intravenous or intramuscular every 6 hours.
Meningitis:
Children: 150 to 200 mg/kg/day intravenous in equally divided doses every 3 to 4 hours.
Endocarditis:
Maximum dose: 12 g/day.
Bacterial Endocarditis Prophylaxis:
Children: 50 mg/kg intravenous or intramuscular as a single dose 30 to 60 minutes before procedure.
Respiratory Tract Infection:
Less than 40 kg: 25 to 50 mg/kg/day intravenous or intramuscular in equally divided doses every 6 to 8 hours.
40 kg or more: 250 to 500 mg intravenous or intramuscular every 6 hours.
20 kg or less: 50 mg/kg/day orally in equally divided doses every 6 to 8 hours.
Greater than 20 kg: 250 mg orally every 6 hours.
Skin or Soft Tissue Infection:
Less than 40 kg: 25 to 50 mg/kg/day intravenous or intramuscular in equally divided doses every 6 to 8 hours.
40 kg or more: 250 to 500 mg intravenous or intramuscular every 6 hours.
Urinary Tract Infection:
Parenteral:
Less than 40 kg: 50 mg/kg/day intravenous or intramuscular in equally divided doses every 6 to 8 hours.
40 kg or more: 500 mg intravenous or intramuscular every 6 hours.
20 kg or less: 25 mg/kg orally every 6 hours.
Greater than 20 kg: 500 mg orally every 6 hours.
Surgical Prophylaxis:
Liver transplant:
1 month or older: Ampicillin 50 mg/kg intravenous plus cefotaxime 50 mg/kg intravenous at induction of anesthesia and every 6 hours for 48 hours after final surgical closure.
How is ampicillin available?
Ampicillin is available in the following dosage forms and strengths:
Oral capsule: 250 mg, 500 mg
Powder for solution: 100 mg, 250 mg, 500 mg, 1 g
What should I do in case of an emergency or overdose?
In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.
What should I do if I miss a dose?
If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.
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