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Ampicillin
Overview
Active ingredients
Source: NDC Directory| Ingredient | Strength | RxCUI | Monograph |
|---|---|---|---|
| Ampicillin Trihydrate | 250 mg/1 | 308212 | — |
| Ampicillin Trihydrate | 500 mg/1 | 308212 | — |
Forms, strengths and routes
Source: NDC DirectoryPharmacologic classes are listed in the class section below.
Pharmacologic class
Source: NDC Directory| Class | Type | Browse |
|---|---|---|
| Penicillin-class Antibacterial [EPC] | EPC | All 38 members |
| Penicillins [CS] | CS | All 38 members |
Regulatory status
Source: Drugs@FDANDC Directory| Product | Trade name | Form | Strength | Ingredient | Status | TE | Flags |
|---|---|---|---|---|---|---|---|
| 064082-001 | AMPICILLIN TRIHYDRATE | CAPSULE | AMPICILLIN/AMPICILLIN TRIHYDRATE | Discontinued | — | ||
| 064082-002 | AMPICILLIN TRIHYDRATE | CAPSULE | AMPICILLIN/AMPICILLIN TRIHYDRATE | Prescription | AB | RS |
Therapeutic equivalence
Source: Orange BookWhat this rating means: Therapeutically equivalent — bioequivalence demonstrated by in vivo or in vitro testing
Codes beginning with “A” indicate products the FDA considers therapeutically equivalent. Codes beginning with “B” indicate bioequivalence has not been established. See methodology.
Approval history
Source: Drugs@FDA| Type | No. | Action | Status | Date | Review |
|---|---|---|---|---|---|
| Supplement | 23 | Labeling | Approved | September 2, 2025 | Standard |
| Supplement | 22 | Labeling | Approved | May 1, 2024 | Standard |
| Supplement | 15 | Labeling | Approved | December 22, 2020 | Standard |
| Supplement | 8 | Labeling | Approved | September 30, 2004 | — |
| Supplement | 4 | Manufacturing (CMC) | Approved | April 7, 1997 | — |
| Supplement | 3 | Manufacturing (CMC) | Approved | November 4, 1996 | — |
| Supplement | 2 | Manufacturing (CMC) | Approved | November 4, 1996 | — |
| Supplement | 1 | Manufacturing (CMC) | Approved | November 4, 1996 | — |
| Original application | 1 | Approved | August 29, 1995 | — |
Prescribing information
Source: openFDA Drug LabelingReproduced verbatim from the Structured Product Labeling submitted to the FDA (effective 20260727). This is the manufacturer's labelling text, not a summary and not advice.
Indications and Usage
openFDA Drug LabelingINDICATIONS AND USAGE To reduce the development of drug-resistant bacteria and maintain the effectiveness of ampicillin capsules, ampicillin for oral suspension and other antibacterial drugs, ampicillin capsules and ampicillin for oral suspension should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. When culture and susceptibility information are available, they should be considered in selecting of modifying antimicrobial therapy, in the absence of such data, local epidemiology and susceptibility patterns contribute to the empiric selection of therapy. Ampicillin capsules and ampicillin for oral suspension are indicated in the treatment of infections caused by susceptible strains of the designated organisms listed below: Infections of the genitourinary tract including gonorrhea: E. coli, P. mirabilis, enterococci , Shigella, S. typhosa and other Salmonella , and nonpenicillinase producing N. gonorrhoeae . Infections of the respiratory tract: Nonpenicillinase- producing H. influenzae and staphylococci, and streptococci including streptococcus pneumoniae . Infections of the gastrointestinal tract: Shigella, S. typhosa and other Salmonella, E. coli, P. mirabilis, and enterococci . Meningitis: N. Meningitides . Bacteriology studies to determine the causative organisms and their susceptibility to ampicillin should be performed. Therapy may be instituted prior to the results of susceptibility testing.
Dosage and Administration
openFDA Drug LabelingDOSAGE AND ADMINISTRATION Adults and pediatric patients weighing over 20 kg: For genitourinary or gastrointestinal tract infections other than gonorrhea in men and women, the usual dose is 500 mg qid in equally spaced doses; severe or chronic infections may require larger doses. For the treatment of gonorrhea in both men and women, a single oral dose of 3.5 grams of ampicillin administered simultaneously with 1 gram of probenecid is recommended. Physicians are cautioned to use no less than the above recommended dosage for the treatment of gonorrhea. Follow-up cultures should be obtained from the original site(s) of infection 7 to 14 days after therapy. In women, it is also desirable to obtain culture test-of-cure from both the endocervical and anal canals. Prolonged intensive therapy is needed for complications such as prostatitis and epididymitis. For respiratory tract infections , the usual dose is 250 mg qid in equally spaced doses. Pediatric patients weighing 20 kg or less: For genitourinary or gastrointestinal tract infections , the usual dose is 100 mg/kg/day total, qid in equally divided and spaced doses. For respiratory tract infections, the usual dose is 50 mg/kg/day total, in equally divided and spaced doses three to four times daily. Doses for children should not exceed doses recommended for adults. All Patients, Irrespective of Age and Weight : Larger doses may be required for severe or chronic infections. Although ampicillin is resistant to degradation by gastric acid, it should be administered at least one-half hour before or two hours after meals for maximal absorption. Except for the single dose regimen for gonorrhea referred to above, therapy should be continued for a minimum of 48 to 72 hours after the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. In infections caused by hemolytic strains of streptococci, a minimum of 10 days’ treatment is recommended to guard against the risk of rheumatic fever or glomerulonephritis (see PRECAUTIONS–Laboratory Tests ). In the treatment of chronic urinary or gastrointestinal infections, frequent bacteriologic and clinical appraisal is necessary during therapy and may be necessary for several months afterwards. Stubborn infections may require treatment for several weeks. Smaller doses than those indicated above should not be used.
Contraindications
openFDA Drug LabelingCONTRAINDICATIONS The use of Ampicillin is contraindicated in individuals with a history of serious hypersensitivity reactions (e.g., anaphylaxis or Stevens-Johnson syndrome) to ampicillin or to other beta-lactam antibacterial drugs. Ampicillin is also contraindicated in infections caused by penicillinase-producing organisms. Ampicillin is contraindicated in patients with a previous history of cholestatic jaundice/hepatic dysfunction associated with treatment with ampicillin.
Warnings
openFDA Drug LabelingWARNINGS SERIOUS AND OCCASIONALLY FATAL HYPERSENSITIVITY (ANAPHYLACTIC) REACTIONS HAVE BEEN REPORTED IN PATIENTS ON PENICILLIN THERAPY. ALTHOUGH ANAPHYLAXIS IS MORE FREQUENT FOLLOWING PARENTERAL THERAPY, IT HAS OCCURRED IN PATIENTS ON ORAL PENICILLINS. THESE REACTIONS ARE MORE LIKELY TO OCCUR IN INDIVIDUALS WITH A HISTORY OF SENSITIVITY TO MULTIPLE ALLERGENS. THERE HAVE BEEN REPORTS OF INDIVIDUALS WITH A HISTORY OF PENICILLIN HYPERSENSITIVITY WHO HAVE EXPERIENCED SEVERE REACTIONS WHEN TREATED WITH CEPHALOSPORINS. BEFORE THERAPY WITH ANY PENICILLIN, CAREFUL INQUIRY SHOULD BE MADE CONCERNING PREVIOUS HYPERSENSITIVITY REACTIONS TO PENICILLINS, CEPHALOSPORINS OR OTHER ALLERGENS. IF AN ALLERGIC REACTION OCCURS, APPROPRIATE THERAPY SHOULD BE CONSIDERED. SERIOUS ANAPHYLACTIC REACTIONS REQUIRE IMMEDIATE EMERGENCY TREATMENT WITH EPINEPHRINE. OXYGEN, INTRAVENOUS STEROIDS, AND AIRWAY MANAGEMENT, INCLUDING INTUBATION, SHOULD ALSO BE ADMINISTERED AS INDICATED. Severe Cutaneous Adverse Reactions Ampicillin may cause severe cutaneous adverse reactions (SCARs), such as toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), exfoliative dermatitis, erythema multiforme, and acute generalized exanthematous pustulosis (AGEP). If patients develop a skin rash, they should be monitored closely, and ampicillin discontinued if lesions progress. Hepatotoxicity Hepatic dysfunction, including hepatitis and cholestatic jaundice has been associated with the use of ampicillin. Hepatic toxicity is usually reversible; however, deaths have been reported. Hepatic function should be monitored at regular intervals in patients with hepatic impairment. Clostridioides difficile -Associated Diarrhea Clostridioides difficile -associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including ampicillin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial drug use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibacterial drug use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated.
Adverse Reactions
openFDA Drug LabelingADVERSE REACTIONS As with other penicillins, it may be expected that untoward reactions will be essentially limited to sensitivity phenomena. They are more likely to occur in individuals who have previously demonstrated hypersensitivity to penicillin and in those with a history of allergy, asthma, hay fever, or urticaria. The following adverse reactions have been reported as associated with the use of ampicillin: Infections and Infestations: Clostridioides difficile -associated diarrhea (see WARNINGS section). Gastrointestinal : glossitis, stomatitis, nausea, vomiting, enterocolitis, pseudomembranous colitis, and diarrhea. These reactions are usually associated with oral dosage forms of the drugs. Hypersensitivity Reactions : Severe cutaneous adverse reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), angioedema, and acute generalized exanthematous pustulosis (AGEP) have been reported in beta-lactam antibiotics (see WARNINGS ). An erythematous, mildly pruritic, maculopapular skin rash has been reported fairly frequently. The rash, which usually does not develop within the first week of therapy, may cover the entire body including the soles, palms, and oral mucosa. The eruption usually disappears in three to seven days. Other hypersensitivity reactions that have been reported are: skin rash, pruritus, urticaria, erythema multiforme, and an occasional case of exfoliative dermatitis. Linear IgA bullous dermatosis has been reported. Anaphylaxis is the most serious reaction experienced and has usually been associated with the parenteral dosage form of the drug. NOTE : Urticaria, other skin rashes, and serum sickness-like reactions may be controlled by antihistamines, and, if necessary, systemic corticosteroids. Whenever such reactions occur, ampicillin should be discontinued unless, in the opinion of the physician, the condition being treated is life-threatening, and amenable only to ampicillin therapy. Serious anaphylactic reactions require emergency measures (see WARNINGS ). Liver : Moderate elevation in serum glutamic oxaloacetic transaminase (SGOT) has been noted, but the significance of this finding is unknown. Hemic and Lymphatic Systems : Anemia, thrombocytopenia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported during therapy with penicillins. These reactions are usually reversible on discontinuation of therapy and are believed to be hypersensitivity phenomena. Other adverse reactions that have been reported with the use of ampicillin are laryngeal stridor and high fever. An occasional patient may complain of sore mouth or tongue as with any oral penicillin preparation.
Drug Interactions
openFDA Drug LabelingDrug Interactions When administered concurrently, the following drugs may interact with ampicillin. Allopurinol : Substantially increased incidence of skin rashes in patients receiving both drugs as compared to patients receiving ampicillin alone. It is not known whether this potentiation of ampicillin rashes is due to allopurinol or the hyperuricemia present in these patients. Bacteriostatic Antibiotics : Chloramphenicol, erythromycins, sulfonamides, or tetracyclines may interfere with the bactericidal effect of penicillins. This has been demonstrated in vitro; however, the clinical significance of this interaction is not well-documented. Oral Contraceptives : May be less effective and increased breakthrough bleeding may occur. Probenecid : May decrease renal tubular secretion of ampicillin resulting in increased blood levels and/or ampicillin toxicity.
Mechanism of Action
openFDA Drug LabelingMechanism of Action Ampicillin is similar to penicillin in its bactericidal action against susceptible bacteria during the stage of active multiplication. It acts through the inhibition of cell wall biosynthesis that leads to the death of the bacteria.
Description
openFDA Drug LabelingTo reduce the development of drug-resistant bacteria and maintain the effectiveness of ampicillin and other antibacterial drugs, ampicillin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. DESCRIPTION Ampicillin trihydrate is a semisynthetic penicillin derived from the basic penicillin nucleus, 6-aminopenicillanic acid. Ampicillin is designated chemically as (2S, 5 R , 6 R )-6-[( R )-2-Amino-2-phenylacetamido]-3,3- dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0] heptane-2-carboxylic acid. Its structural formula is: Molecular formula: C 16 H 19 N 3 O 4 S · 3 H 2 O Molecular weight: 403.5 Ampicillin capsules, USP for oral administration provide ampicillin trihydrate equivalent to 250 mg and 500 mg ampicillin USP. Inactive ingredients: ammonium hydroxide, black iron oxide, gelatin, magnesium stearate, potassium hydroxide, propylene glycol, shellac, sodium lauryl sulfate and titanium dioxide. Meets USP dissolution test 2. str
Overdosage
openFDA Drug LabelingOVERDOSAGE In case of overdosage, discontinue medication, treat symptomatically and institute supportive measures as required. In patients with renal function impairment, ampicillin-class antibiotics can be removed by hemodialysis but not by peritoneal dialysis.
How Supplied / Storage and Handling
openFDA Drug LabelingHOW SUPPLIED Ampicillin capsules, USP: Each capsule, for oral administration, contains ampicillin trihydrate equivalent to 250 mg or 500 mg ampicillin USP, and are supplied as: 250 mg: white opaque colored cap and body, hard gelatin capsule filled with white to off-white granular powder, imprinted with “AMP” on cap and “250” on body, with black ink. Bottles of 100 NDC 59651-550-01 Bottles of 500 NDC 59651-550-05 500 mg: white opaque colored cap and body, hard gelatin capsule filled with white to off-white granular powder, imprinted with “AMP” on cap and “500” on body, with black ink. Bottles of 100 NDC 59651-551-01 Bottles of 500 NDC 59651-551-05 Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature]. Dispense in a tight container. All brands listed are the trademarks of their respective owners and are not trademarks of Aurobindo Pharma Limited. Distributed by: Aurobindo Pharma USA, Inc. 279 Princeton-Hightstown Road East Windsor, NJ 08520 Manufactured by: Aurobindo Pharma Limited Hyderabad-500 032, India Revised: 08/2025
Adverse event reports
Source: openFDA FAERSAttributed to this product's most-reported active ingredient: AMPICILLIN TRIHYDRATE. Combination products with more than six active ingredients are not attributed, because a report count summed across a long ingredient list measures the list, not the medicine.
Packaging and NDCs
Source: NDC Directory| Package NDC | Product NDC | Labeler | Description | Marketing start |
|---|---|---|---|---|
| 59651-550-01 | 59651-550 | Aurobindo Pharma Limited | 100 CAPSULE in 1 BOTTLE (59651-550-01) | October 31, 2023 |
| 59651-550-05 | 59651-550 | Aurobindo Pharma Limited | 500 CAPSULE in 1 BOTTLE (59651-550-05) | October 31, 2023 |
| 59651-551-01 | 59651-551 | Aurobindo Pharma Limited | 100 CAPSULE in 1 BOTTLE (59651-551-01) | October 31, 2023 |
| 59651-551-05 | 59651-551 | Aurobindo Pharma Limited | 500 CAPSULE in 1 BOTTLE (59651-551-05) | October 31, 2023 |
| 70518-2607-1 | 70518-2607 | REMEDYREPACK INC. | 28 CAPSULE in 1 BOTTLE, PLASTIC (70518-2607-1) | July 17, 2025 |
| 0781-2145-01 | 0781-2145 | Sandoz Inc | 100 CAPSULE in 1 BOTTLE (0781-2145-01) | August 29, 1995 |
| 0781-2145-05 | 0781-2145 | Sandoz Inc | 500 CAPSULE in 1 BOTTLE (0781-2145-05) | August 29, 1995 |
| 59651-550 | 59651-550 | Aurobindo Pharma Limited | — | October 31, 2023 |
| 59651-551 | 59651-551 | Aurobindo Pharma Limited | — | October 31, 2023 |
| 70518-2607 | 70518-2607 | REMEDYREPACK INC. | — | February 28, 2020 |
| 0781-2145 | 0781-2145 | Sandoz Inc | — | August 29, 1995 |
Sources for this page
| Dataset | Agency | Used for |
|---|---|---|
| NDC Directory | FDA | Identity, ingredients, strengths, forms, routes, labelers, packages |
| Drugs@FDA | FDA | Application, sponsor, submissions, review documents, marketing status |
| Orange Book | FDA | Therapeutic equivalence codes, reference drug flags, patents, exclusivity |
| Drug Labeling | FDA / NLM | Prescribing information reproduced above |
| FAERS | FDA | Adverse event report counts |
Generated September 25, 2026 · 12 sections on this page.