Does Lovaza (omega-3-acid ethyl esters) cause side effects?

Lovaza (omega-3-acid ethyl esters) is a fat-regulating (antilipemic) drug used in addition to diet to reduce triglyceride (TG, a fat-carrying particle in the blood) levels in adult patients with severe elevations in blood levels of TG (≥mg/dL). 

TG is composed of three fatty acids as well as glycerol, and like cholesterol, comes from either the diet or the liver. High levels of TG in the blood are associated with conditions such as obesity, insulin resistance, and poorly controlled diabetes mellitus that contribute to the risk of hardening of the arteries (atherosclerosis) responsible for coronary artery disease (angina and heart attacks) and strokes

The precise way in which Lovaza works is not clear; its proposed mechanism of action is by decreasing the amount of TG produced by the liver and increasing the removal of TG by the liver. 

Serious side effects of Lovaza are rare and may include

  • increased bleeding (symptoms include easy bleeding from cuts/bruising, black/tarry stools, and vomit that looks like coffee grounds).

Drug interactions of Lovaza include anticoagulants (blood thinners) such as

Some drugs may increase TG levels, so patients should tell their doctor or pharmacist of the following medications before using Lovaza:

Lovaza contains ethyl esters of omega-3 fatty acids which are obtained from the oil of several fish sources and should be used with caution in patients with known sensitivity or allergy to fish and/or shellfish. 

There are no adequate and well-controlled studies of Lovaza in pregnant women. Lovaza should be used during pregnancy only if the potential benefit to the patient justifies the potential risk to the fetus. 

Lovaza is excreted in human milk and caution should be exercised when administering Lovaza to breastfeeding women.

What are the important side effects of Lovaza (omega-3-acid ethyl esters)?

Upset stomach, burping, and strange tastes in may occur. If these effects persist or worsen, patients should notify their doctor. They also should tell their doctors immediately if any of the following rare but serious side effects that suggest increased bleeding occur:

Lovaza (omega-3-acid ethyl esters) side effects list for healthcare professionals

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Adverse reactions reported in at least 3% of subjects treated with Lovaza and at a greater rate than placebo based on pooled data across 23 clinical trials are listed in Table 1.

Table 1. Adverse Reactions Occurring at Incidence ≥3% and Greater than Placebo in Clinical Trials of Lovaza

Adverse ReactionaLovaza
(n = 655)
(n = 370)
Taste perversion2741<1
a Trials included subjects with HTG and severe HTG.

Additional adverse reactions from clinical trials are listed below:

Digestive System

Constipation, gastrointestinal disorder, and vomiting.

Metabolic And Nutritional Disorders

Increased ALT and increased AST.


Pruritus and rash.

Postmarketing Experience

In addition to adverse reactions reported from clinical trials, the events described below have been identified during post-approval use of Lovaza. Because these events are reported voluntarily from a population of unknown size, it is not possible to reliably estimate their frequency or to always establish a causal relationship to drug exposure.

The following events have been reported:

  • anaphylactic reaction,
  • hemorrhagic diathesis,
  • urticaria.

What drugs interact with Lovaza (omega-3-acid ethyl esters)?

Anticoagulants Or Other Drugs Affecting Coagulation

Some trials with omega-3-acids demonstrated prolongation of bleeding time. The prolongation of bleeding time reported in these trials has not exceeded normal limits and did not produce clinically significant bleeding episodes. Clinical trials have not been done to thoroughly examine the effect of Lovaza and concomitant anticoagulants. Patients receiving treatment with Lovaza and an anticoagulant or other drug affecting coagulation (e.g., anti-platelet agents) should be monitored periodically.

Does Lovaza (omega-3-acid ethyl esters) cause addiction or withdrawal symptoms?

Drug Abuse And Dependence

Lovaza does not have any known drug abuse or withdrawal effects.

Treatment & Diagnosis

Medications & Supplements

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 8/12/2020
FDA Prescribing Information

Professional side effects, drug interactions, and addiction sections courtesy of the U.S. Food and Drug Administration.