Prescription Fish Oil vs. Supplements

Both over-the-counter (OTC) and prescription fish oil supplements contain omega-3 fatty acids, the “good” fats in fish that can help reduce triglyceride levels. However, prescription formulations have significantly higher active compound concentrations and are typically given only to manage very high triglyceride levels.

The Benefits of Fish Oil

Omega-3 fatty acids are a type of “good” polyunsaturated fats. They include bioactive fatty acids known as:

• Alpha-linolenic acid (ALA)
• Docosahexaenoic acid (DHA)
• Eicosapentaenoic acid (EPA)

Omega-3 fatty acids are thought to offer many health benefits:

• Reducing triglycerides
• Increasing “good” HDL cholesterol levels
• Decreasing the risk of atherosclerosis (hardening of the arteries)
• Preventing blood clots
• Reducing inflammation

While omega-3s are found in fatty fish (such as salmon and mackerel) and other foods, they come in much higher amounts in OTC and prescription fish oil supplements.

OTC Omega-3 Supplements

OTC omega-3 supplements contain ample quantities of ALA but comparatively low levels of DHA and EPA. The problem with this is that EPA is the compound known to reduce vascular inflammation (which contributes to atherosclerosis), while DHA is the compound that exerts the greatest impact on triglycerides.

While ALA has positive effects on blood lipids (fats), DHA and EPA appear to be the compounds that can deliver actual “heart-healthy” benefits. Even so, the benefits of OTC fish oil supplements remain largely unproven.

Prescription Fish Oil Supplements

Unlike their OTC counterparts, prescription fish oil supplements are formulated to deliver high concentrations of DHA and EPA. Moreover, these compounds are delivered at doses proven to reduce triglyceride levels based on rigorous clinical trials overseen by the FDA. Currently, prescription fish oil supplements are reserved solely for the treatment of severe hypertriglyceridemia (high triglyceride levels).

Types of Omega-3 Supplements

There are other key differences in the composition and production of OTC vs. prescription fish oil supplements

OTC Omega-3 Supplements

OTC omega-3 supplements found in stores are commonly made from fish oil but can also be derived from other marine animals (such as krill) and occasionally sea plants (like algae). Based on the medium used, the concentration of DHA and EPA can vary from one OTC supplement to the next.

Interestingly, fish oil tends to have less DHA and EPA than either krill or algae oil even though it is the most common omega-3 supplement. Similarly, the DHA and EPA content in krill oil has greater bioavailability (meaning the proportion of drug entering the bloodstream) than either fish or algae oil.

Even so, the amount of DHA and EPA contained in any of the OTC supplements falls well short of the "heart-healthy" claims made by manufacturers.

Prescription Fish Oil

Research has shown that the benefits of DHA and EPA are dose-dependent, meaning that better results are received at higher doses. And, until you reach a certain threshold, you may get no benefit at all.

With DHA, for example, you need to take around 600 milligrams (mg) per day to achieve a 20% drop in triglycerides. Lesser doses do little to alter triglyceride levels.

This is a problem because OTC supplements only deliver 120 mg of DHA per dose (and often far less because supplements in the United States are not strictly regulated).

Another issue is that high doses of DHA may enhance the triglyceride-lowering effects of EPA but also increase levels of “bad” LDL cholesterol that clog arteries. As such, getting more and more DHA may end up increasing—rather than lowering—the risk of atherosclerosis, particularly in those with uncontrolled high cholesterol.

Prescription fish oil supplements address these shortcomings by ensuring that DHA and EPA doses are at therapeutic levels.

There are two prescription omega-3 drugs approved for use in the United States:

• Lovaza (omega-3-acid ethyl esters): Prescribed at a daily dose of 1,860 mg EPA and 1,500 mg DHA
• Vascepa (icosapent ethyl): Prescribed at a daily dose of 4 grams EPA

Why Do I Need Prescription Fish Oil?

The main difference between OTC and prescription supplements is that OTC supplements are not approved to prevent, treat, or manage any medical condition. While OTC supplements are generally regarded as safe, their benefits are often presumed rather than proven.

By contrast, prescription drugs in the United States are regulated by the FDA and are licensed for use in treating specific medical conditions.

Prescription Fish Oil Supplements

Lovaza is approved by the FDA for the treatment of adults with severe hypertriglyceridemia (triglycerides of 500 mg/dL or more) in conjunction with a heart-healthy diet. Vascepa is approved for the same but is more suitable for people with high LDL cholesterol.

Each is taken by mouth as a capsule. You can either take two capsules twice daily with food or four capsules once daily with food.

Generic forms are available.

Over-the-Counter Omega-3 Supplements

There are no indications for the use of OTC omega-3 supplements and no recommended dose. As a general rule, never exceed the dose listed on the manufacturer’s label.

Because OTC and prescription fish oil supplements contain more or less the same ingredients, you can take 10 or 12 OTC supplements to get the right amount of DHA and EPA. And you’ll likely lower your triglycerides in the same way.

But the problem with this is twofold:

• The more OTC fish oil supplement you take, the greater the risk and severity of side effects.
• You may end up taking too much EPA and increase your “bad” LDL cholesterol levels.

To avoid such problems, speak with your healthcare provider before starting any new supplement. Self-treating any medical condition may end up causing more harm than good.

Potential Side Effects and Risks

Both OTC and prescription fish oil supplements can cause side effects such as burping, heartburn, and joint pain, particularly if they’re taken in excessive quantities. OTC fish oil supplements, however, come with a few more.

Over-the-Counter Omega-3 Supplements

Other possible side effects of OTC omega-3 supplements include:

• Stomach pain or discomfort
• Nausea or vomiting
• Constipation
• Diarrhea
• Changes in taste

If taken in excess, fish oil can affect blood clotting and increase bruising and bleeding. Even so, studies suggest that doses of up to 10,000 mg per day may be safe for short-term use with no significant impact on blood clotting.

OTC omega-3 supplements should also be avoided by people with fish allergies.

Prescription Fish Oil Supplements

Lovaza and Vascepa can cause many of the same side effects as their OTC counterparts, but they do so at therapeutic doses. The most common side effects are burping, upset stomach, and changes in taste).

It is not known if Lovaza and Vascepa can cause allergies in people who are allergic to fish or shellfish. If you have a known fish or shellfish allergy, speak with your healthcare provider before using either supplement.

Safety and Purity

Supplements and prescription drugs containing omega-3 fatty acids are not created equally. Each is subject to different rules and regulations by the FDA.

Over-the-Counter Omega-3 Supplements

Supplements sold at your local drugstore are classified as “foods” by the FDA. This means that it is the manufacturer’s responsibility to make sure that these products are safe, free of contaminants, correctly labeled, and made in a clean environment.

Supplement labels are not allowed to state that they can treat or prevent any medical condition. However, they are not strictly regulated, and the FDA will only take action if it receives enough complaints.

To ensure safety, only buy supplements that have been voluntarily submitted for certification by an independent organization like the U.S. Pharmacopeia (USP), NSF International, or ConsumerLab. The certification confirms that the ingredients are pure and as described on the product label.

Prescription Fish Oil Supplements

Prescription drugs are regulated more stringently. To be approved, the product must undergo extensive lab, animal, and human testing to ensure that it is safe and effective for different populations of adults or children.

In addition to indications of use, the FDA will list contraindications (meaning when or in whom the drug cannot be used). Information about recommended dosage and storage will be included.

Prescription fish oil supplements should be stored at 77 F (25 C). Short excursions in temperature between 59 F and 86 F (15 C and 30 C) are acceptable. Discard any expired medications. Keep out of the reach of children and pets.

Summary

Over-the-counter and prescription fish oil supplements contain more or less the same ingredients. But prescription supplements like Lovaza and Vascepa contain higher amounts of compounds DHA and EPA that are known to reduce triglycerides. You can increase the number of OTC supplements to reach the same dose but would likely increase the risk of side effects.

The FDA says that you should not take more than 2 grams (2,000 mg) of OTC fish oil supplements a day unless under the direction of a healthcare provider.