What the label lists and what reports show
Protamine side effects
Protamine's FDA label lists its adverse reactions in its own words. FAERS holds 1,837 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 pain (1,032 reports).
- Generic listed
- Boxed warning
Check it at the source: the protamine FDA label on DailyMed (effective April 29, 2025, Fresenius Kabi USA, LLC); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsTo report SUSPECTED ADVERSE REACTIONS, contact Fresenius Kabi USA, LLC at 1-800-551-7176 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. The intravenous administration of protamine sulfate may cause a sudden fall in blood pressure and bradycardia. Other reactions include transitory flushing and feeling of warmth, dyspnea, nausea, vomiting and lassitude. Back pain has been reported in conscious patients undergoing such procedures as cardiac catheterization. Severe adverse reactions have been reported including: (1) Anaphylaxis that resulted in severe respiratory distress, circulation collapse and capillary leak (see PRECAUTIONS ). Fatal anaphylaxis has been reported in one patient with no prior history of allergies; (2) Anaphylactoid reactions with circulatory collapse, capillary leak, and noncardiogenic pulmonary edema; acute pulmonary hypertension. …
Source: FDA drug label, Fresenius Kabi USA, LLC, effective April 29, 2025 (SPL set c76876da-b9a8-45d0-9278-7df3288d3a06), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,837 reports list protamine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 686 are coded as a death and 727 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 24 reactions below, 1 is 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
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Protamine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions