Ampicillin works by interfering with the ability of bacteria to form cell walls. The cell walls of bacteria are vital for their survival. They keep unwanted substances from entering their cells and stop the contents of their cells from leaking out. Ampicillin impairs the bonds that hold the bacterial cell wall together. This allows holes to appear in the cell walls and so kills the bacteria.
A history of a previous hypersensitivity reaction to any of the penicillins is a contraindication.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bloody stools; severe diarrhea; stomach pain/cramps; vaginal irritation or discharge.
Probably do not affect hormonal birth control such as pills, patch, or ring, some antibiotics may decrease their effectiveness. This could cause pregnancy. Examples include rifamycins such as rifampin or rifabutin. Be sure to ask your doctor or pharmacist if you should use additional reliable birth control methods while using this antibiotic. Ampicillin may cause false positive results with certain diabetic urine testing products (cupric sulfate-type). This drug may also affect the results of certain lab tests. Make sure laboratory personnel and your doctors know you use this drug.
Precautions & Warning:
Serious and occasionally fatal hypersensitivity (anaphylactoid) 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 apt to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. The possibility of superinfections with mycotic organisms or bacterial pathogens should be kept in mind during therapy. In such cases, discontinue the drug and substitute appropriate treatment.
Use in Pregnancy and Nursing Mothers:
Ampicillin is excreted in trace amounts in human milk. Therefore, caution should be exercised when Ampicillin-class antibiotics are administered to a nursing woman.
Treatment/antidote in The Event of Overdose:
Symptoms: Neurologic symptoms, including convulsions. Treatment: Both ampicillin and sulbactam may be removed by hemodialysis.