A toxin from the outer wall of certain bacteria that can contaminate poorly made injectable products and trigger fever, chills, and serious reactions.
Updated Jul 18, 2026
An endotoxin is a toxic component of the outer cell wall of certain bacteria, released when the bacteria break down. When it contaminates an injectable product, it can cause fever, chills, low blood pressure, and other serious reactions, even if the product no longer contains live bacteria.
Controlling endotoxin levels is a routine part of regulated sterile drug manufacturing. It is a documented risk with unregulated or grey-market peptides and injectables made without that oversight, which is one reason the source and quality controls of an injected product matter.
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Related terms
503B outsourcing facility — An FDA-registered compounding facility that can make larger batches under CGMP standards and FDA inspection — a step above 503A, but still not an FDA-approved manufactured drug.
503A compounding — A section of federal law that lets a licensed pharmacy compound a medication for an individual patient's prescription, outside the FDA approval process.
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