Is Icosapent Ethyl Derived from Fish? Unpacking the Link to Fish Oil

December 16, 2025 •

4 min read

The US Food and Drug Administration (FDA) first approved icosapent ethyl (brand name Vascepa) in 2012 for the treatment of severe hypertriglyceridemia. And yes, icosapent ethyl is derived from fish, but it is a highly purified form of the omega-3 fatty acid eicosapentaenoic acid (EPA), which distinguishes it significantly from standard fish oil supplements.

Quick Summary

Icosapent ethyl, sold as the prescription medication Vascepa, originates from fish oil but undergoes extensive purification. This process isolates the single omega-3 EPA, creating a highly refined product distinct from standard over-the-counter fish oil supplements.

Key Points

Fish Origin Confirmed: Icosapent ethyl is sourced from fish oil, primarily from species like sardines and anchovies, as the raw material for production.
High Purity and Refinement: It undergoes extensive processing, including molecular distillation and chemical refinement, to isolate the omega-3 fatty acid EPA, removing other fatty acids like DHA and contaminants.
Prescription-Grade: Unlike unregulated over-the-counter fish oil supplements, icosapent ethyl is a prescription medication regulated by agencies like the FDA, ensuring strict quality and potency.
EPA-Exclusive: The final product is a highly concentrated, pure EPA ethyl ester, which is key to its specific therapeutic effects for cardiovascular health.
Therapeutic Distinction: The rigorous purification creates a product with proven cardiovascular risk-reducing benefits that are not comparable to those of general fish oil supplements.
Not Interchangable: Icosapent ethyl and regular fish oil supplements are not the same and should not be used as substitutes for one another due to differences in composition and regulation.

What is Icosapent Ethyl?

Icosapent ethyl (IPE) is a medication containing a highly purified, ethyl ester form of the omega-3 fatty acid eicosapentaenoic acid (EPA). It is most widely recognized by its brand name, Vascepa. Prescribed by doctors, its primary uses are to reduce very high triglyceride levels and to lower the risk of cardiovascular events, such as heart attacks and strokes, in specific high-risk patients already on statin therapy. The key to its efficacy and differentiation lies in its potent, single-component composition.

Unlike traditional fish oil supplements that contain a mix of various omega-3s, including both EPA and DHA (docosahexaenoic acid), icosapent ethyl is exclusively EPA. This critical difference is the result of a rigorous and complex manufacturing process that begins with a raw material derived from fish.

The Fishy Origin: How Icosapent Ethyl is Made

Yes, the journey of icosapent ethyl begins with fish. The source oil is typically extracted from cold-water marine fish, like sardines and anchovies, which are naturally rich in omega-3 fatty acids. However, the process doesn't stop there. The fish oil is merely the starting point, and what happens next is what truly defines the product.

The Multi-Step Purification Process

The raw fish oil undergoes a series of sophisticated chemical steps to achieve the high level of purity required for a pharmaceutical-grade product:

Extraction: The omega-3 rich oil is initially extracted from the fish biomass.
Molecular Distillation: This process is used to concentrate the EPA and remove impurities and other fatty acids. This step significantly increases the percentage of EPA in the oil.
Esterification: The concentrated EPA is then chemically converted into an ethyl ester form. This modification increases its stability and improves its absorption by the body.
Further Refinement: Additional steps, such as chromatography, are often used to further purify the ethyl ester, ensuring that the final product contains at least 96% pure EPA ethyl ester and effectively eliminating contaminants like mercury or PCBs.

This extensive manufacturing process is the reason why icosapent ethyl is considered a pharmaceutical rather than a simple dietary supplement.

Icosapent Ethyl vs. Standard Fish Oil Supplements

While both icosapent ethyl and over-the-counter (OTC) fish oil supplements originate from fish, they are not interchangeable. The differences are vast and include regulatory oversight, composition, potency, and evidence of efficacy.

Composition: OTC fish oils contain a mix of fatty acids, including both EPA and DHA. Icosapent ethyl, by contrast, is a single-molecule, highly concentrated EPA product.
Purity: The pharmaceutical-grade manufacturing of icosapent ethyl ensures consistent, high purity, and the removal of impurities found in natural fish oil. OTC supplements are not held to the same stringent standards.
Regulation: The FDA regulates icosapent ethyl as a prescription drug, guaranteeing its safety, potency, and manufacturing quality. OTC fish oil supplements are regulated as dietary supplements, which have less rigorous oversight.
Efficacy: Clinical trials like REDUCE-IT have demonstrated that icosapent ethyl can significantly reduce major adverse cardiovascular events in certain patient populations. Similar cardiovascular benefits have not been consistently shown with general fish oil supplements.

Comparison Table: Icosapent Ethyl vs. Common Fish Oil Supplements


Feature	Icosapent Ethyl (e.g., Vascepa)	Common OTC Fish Oil Supplements
Purity/Composition	Highly refined, single EPA ethyl ester (≥96% pure).	Variable; contains a mix of EPA, DHA, and other fatty acids.
EPA/DHA Content	EPA only.	Contains both EPA and DHA.
FDA Regulation	Regulated as a prescription drug, with strict quality control.	Regulated as a dietary supplement, with less stringent oversight.
Purpose	To lower very high triglycerides and reduce major cardiovascular events.	Supports general heart health, but clinical benefits are not consistent across studies.
Potency	Much higher concentration than typical supplements.	Lower potency, and content can vary by brand and batch.
Side Effects	Potential side effects include joint pain, edema, and atrial fibrillation.	Generally safe, but can cause minor digestive upset.
Allergic Risk	Requires caution in patients with fish/shellfish allergies, though purification may reduce risk.	Can trigger allergic reactions in individuals sensitive to fish.

Why the Refinement Process Matters

The rigorous purification of icosapent ethyl is critical for its therapeutic effect. The isolation of EPA from DHA is particularly important because, unlike icosapent ethyl, fish oil products containing both EPA and DHA have been shown to potentially increase LDL-C levels. By delivering a consistently high dose of pure EPA, icosapent ethyl provides a predictable and specific mechanism of action that has been validated in large-scale clinical trials. This level of standardization and reliability is impossible to achieve with unregulated supplements.

Conclusion: The Final Word on its Fish Origin

To definitively answer the question, 'is icosapent ethyl derived from fish?'—yes, it is. However, it's a simplification that misses the crucial nuance. While its source is fish oil, icosapent ethyl is not a simple fish oil product. It is a highly purified, potent, and single-molecule ethyl ester of EPA that has been manufactured to pharmaceutical standards. This extensive refinement process removes impurities and separates it from other fatty acids, resulting in a prescription medication with specific, evidence-based cardiovascular benefits that are not comparable to those of over-the-counter fish oil supplements.

For more detailed prescribing information, refer to the official FDA documents VASCEPA® (icosapent ethyl) Capsules Prescribing Information.

Frequently Asked Questions

No, icosapent ethyl is a highly purified, prescription-only omega-3 medication and is not the same as an over-the-counter fish oil supplement. It contains only the omega-3 EPA, not the mixture of EPA and DHA found in most supplements.

Yes, the difference is significant. Icosapent ethyl is purified to be at least 96% EPA ethyl ester, is FDA-regulated, and is clinically proven for cardiovascular risk reduction. Regular fish oil supplements are less purified, contain a mix of omega-3s, and are not held to the same pharmaceutical standards.

People with known fish or shellfish allergies should exercise caution. Although the product is highly purified, the omega-3 is obtained from the oil of fish. It is not known whether the purification process completely eliminates the risk of an allergic reaction.

Icosapent ethyl is more expensive because it is a pharmaceutical-grade product that undergoes a complex, multi-step purification process to create a single-molecule, high-potency drug. This requires significant investment in manufacturing and clinical trials to achieve regulatory approval.

The fish oil used as the initial source for icosapent ethyl is typically extracted from cold-water marine fish like sardines and anchovies, which are naturally rich in EPA.

No, icosapent ethyl contains only the ethyl ester of eicosapentaenoic acid (EPA). The extensive purification process removes all other fatty acids, including docosahexaenoic acid (DHA), from the final product.

Yes, generic icosapent ethyl is also derived from fish oil. Generic medications contain the same active ingredients and have the same manufacturing origin as their brand-name counterparts, but they may be sold at a lower cost.

The primary medical uses for icosapent ethyl are to reduce very high triglyceride levels in adults and to lower the risk of cardiovascular events like heart attack and stroke in high-risk patients.