Generic Ampicillin

Common use

Ampicillin is a broad-spectrum antibiotic from aminopenicillin group. Its mechanism of action is anti-bacterial and consists in inhibition of construction of bacteria cell walls sensitive to Ampicillin. It is not destroyed in acidic content of stomach, is easily absorbed. Ampicillin is active toward gram positive microorganisms and also some gram negative ones (salmonella, schigella, proteus, E. coli, Klebsiella pneumoniae, Haemophilus influenzae, formerly called Pfeiffer's bacillus) and is used for treatment of the diseased provoked by mixed bacteria. Microorganisms producing penicillase are resistible to Ampicillin. This medication is used to treat pneumonia and other infectious diseases of respiratory, urogenital, gastrointestinal systems.



Dosage and directions

Take exactly as prescribed. ampicillin capsules should be taken with a full glass of water, a half hour before or 2 hours after a meal.



Precautions

If are allergic to penicillin or cephalosporin antibiotics, contact your doctor first than to take this drug. This medication may cause diarrhea so inform your doctor if you have it before to take any drug for diarrhea. Ampicillin may show a false positive result of in certain urine glucose tests. If you have taken Ampicillin for a long time before it may appear ineffective in your organism due to so called superinfection, inform your doctor if your symptoms do not improve or get worse.



Contraindications

Hypersensitivity to Ampicillin. Cautiousness should be exercised if there is liver failure, asthma, hay fever.



Possible side effect

Colitis, diarrhea, fever, itching, nausea, rash, sore tongue or mouth, vomiting.



Drug interaction

Ampicillin enhances effect of the orally taken medications which prevent blood clot formation. This medication may interfere work of certain oral contraceptives.



Missed dose

Never take a double dose of this medication. If take this medication twice daily and missed a dose, take it as soon as you remember, take the next dose 5-6 hours later. If you take the drug thrice daily, take the missed dose as soon as you remember and do the next one in 2-4 hours.



Overdose

If you suppose that you took too much Ampicillin and have symptoms of allergy (hives, rush) contact your doctor immediately.





Storage

Store at room temperature between 59 and 86 degrees F (15-30 degrees C) away from light and moisture.



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care advisor or doctor in charge of the case. We disclaim all responsibility for the reliability of this information. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)