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What the label lists and what reports show

Ampicillin side effects

Ampicillin's FDA label lists its adverse reactions in its own words. FAERS holds 8,240 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is drug hypersensitivity (606 reports).

  • Generic listed
  • A presentation discontinued

Check it at the source: the ampicillin FDA label on DailyMed (effective February 21, 2025, Sandoz Inc); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse 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 penicillins 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: Gastrointestinal Glossitis, stomatitis, black “hairy” tongue, nausea, vomiting, enterocolitis, pseudomembranous colitis, and diarrhea. (These reactions are usually associated with oral dosage forms.) Hypersensitivity Reactions Skin rashes and urticaria have been reported frequently. A few cases of exfoliative dermatitis and erythema multiforme have been reported. Linear IgA bullous dermatosis has been reported. …

Source: FDA drug label, Sandoz Inc, effective February 21, 2025 (SPL set 64a04e8c-8f78-46b3-8f45-56ef225a4f74), via openFDA; the full label on DailyMed

What do FAERS reports show?

8,240 reports list ampicillin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,308 are coded as a death and 3,455 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 16 reactions below, 5 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

Reports received each year

The 25 most reported reactions

  • Drug Ineffective (a use or a product term, not a reaction)862
  • Foetal Exposure During Pregnancy (a use or a product term, not a reaction)657
  • Drug Hypersensitivity606
  • Maternal Exposure During Pregnancy (a use or a product term, not a reaction)535
  • Premature Baby511
  • Off Label Use (a use or a product term, not a reaction)435
  • Pyrexia375
  • Premature Delivery337
  • Acute Kidney Injury330
  • Renal Failure317
  • Chronic Kidney Disease285
  • Product Use In Unapproved Indication (a use or a product term, not a reaction)281
  • Rash (named in the label)274
  • Pain261
  • Condition Aggravated (a use or a product term, not a reaction)253
  • Dyspnoea248
  • Nausea (named in the label)243
  • Pneumonia (a use or a product term, not a reaction)240
  • Diarrhoea (named in the label)237
  • Sepsis (a use or a product term, not a reaction)221
  • Fatigue205
  • Hypotension205
  • Vomiting (named in the label)197
  • Exposure During Pregnancy (a use or a product term, not a reaction)185
  • Anaemia (named in the label)178

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Ampicillin: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions