DHA (docosahexaenoic acid)

Pronunciation: dee-aitch-AY.

Generic name
docosahexaenoic acid (DHA), an omega-3 fatty acid
Brand names
Sold under many different dietary-supplement brand names; the prescription-strength EPA+DHA combination product is branded Lovaza (United States) or Omacor (United Kingdom, Australia)
Drug class
Omega-3 fatty acid; dietary/natural-health supplement, or (specific prescription-strength combination products only) a licensed medicine for severe/endogenous hypertriglyceridaemia
Form
Softgel, capsule, or liquid (supplement); capsule (prescription-strength product)
Route
Oral
Legal status
Dietary/food/natural-health supplement (no medicine-style pre-market efficacy approval required) in the United States, United Kingdom, European Union, Canada, Australia, and New Zealand. A separate, real prescription-strength combination product (EPA+DHA ethyl esters) is a licensed/registered medicine in the United States, United Kingdom, and Australia.

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Omega-3 Fish Oil 1000 (representative AUST L listed example) (6), Omacor (prescription omega-3-acid ethyl esters 90) (6) · Full directory

What docosahexaenoic acid (DHA), an omega-3 fatty acid is and how it works

DHA (docosahexaenoic acid) is an omega-3 fatty acid found naturally in fish, marine oils, and algae, and is one of the two main omega-3s (along with EPA) in most fish-oil supplements. Taken as an everyday supplement, DHA is regulated as a dietary/food/natural-health supplement, not as a medicine that has been reviewed and approved for treating a disease. Separately, a specific prescription-strength combination of EPA and DHA (branded Lovaza in the United States or Omacor in the United Kingdom and Australia) is a licensed medicine used at a much higher, specific dose to treat severe or endogenous high triglycerides. (1) (2) (7)

It is important to know which of these two very different things you are taking: an everyday DHA/omega-3 supplement (which has not been reviewed by a medicines regulator for treating any disease, though some health claims about heart health or children's brain development have been formally assessed), or a specific prescription omega-3 medicine at a much higher dose used under medical supervision for high triglycerides. Do not assume an everyday supplement can replace a prescription medicine's specific effect on triglycerides, and do not take high-dose omega-3 without medical advice if you are on blood-thinning medicine.

Mechanism of action: how docosahexaenoic acid (DHA), an omega-3 fatty acid works

DHA and EPA are long-chain omega-3 polyunsaturated fatty acids. At prescription-strength doses, proposed triglyceride-lowering mechanisms include inhibition of hepatic acyl-CoA:1,2-diacylglycerol acyltransferase, increased hepatic mitochondrial/peroxisomal beta-oxidation, decreased hepatic lipogenesis, and increased plasma lipoprotein lipase activity, resulting in reduced VLDL and triglyceride synthesis. (2) (3)

What docosahexaenoic acid (DHA), an omega-3 fatty acid is used for

General omega-3 intake / heart health support (everyday supplement)

Widely taken as a source of omega-3 fatty acids to support general health. In the United States, a qualified health claim (a lower tier of evidence than a full authorised claim) allows DHA/EPA products to state that consuming EPA and DHA may reduce the risk of hypertension and coronary heart disease. In the European Union, DHA at 250 mg/day has an EFSA-authorised claim for normal brain development in children aged 12 months-12 years, and 250-500 mg/day EPA+DHA is the EFSA-referenced adult intake for cardiovascular health. In Canada, licensed products may carry authorised claims such as supporting cognitive health and brain function development in children. (1) (4) (5)

Severe or endogenous hypertriglyceridaemia (prescription-strength product only)

The prescription-strength EPA+DHA ethyl ester product (Lovaza/Omacor) is a licensed medicine used as an adjunct to diet to lower very high triglyceride levels. This is a specific, higher-dose (4 g/day), medically supervised use -- not something an everyday over-the-counter DHA supplement is approved to do. In Australia, this same prescription product is also approved as adjuvant treatment for secondary prevention after a heart attack. (2) (3) (6)

Before taking docosahexaenoic acid (DHA), an omega-3 fatty acid

Do not take / not appropriate for

  • Do not take DHA/omega-3 products, at supplement or prescription strength, if you have a known hypersensitivity to fish and/or shellfish, without first checking with your clinician or pharmacist -- most products are fish- or marine-oil derived (algae-oil DHA products are an alternative for some people). (all products, all countries) (2)
  • Do not take the prescription-strength product (Lovaza/Omacor) if you have a known hypersensitivity to it or its components. (prescription product, United States, United Kingdom, Australia) (2)

Tell your clinician about

  • If you take warfarin or another anticoagulant/antiplatelet medicine, since omega-3 (at supplement or prescription strength) can affect bleeding time.
  • If you have a fish or shellfish allergy, so you and your pharmacist can check your specific product's source (fish oil vs algae oil).
  • If you have an irregular heart rhythm (atrial fibrillation or flutter), especially before starting the prescription-strength product.
  • If you have liver problems, since the prescription-strength product requires periodic liver blood tests.
  • If you are pregnant or breastfeeding.
(2) (7)

How to take docosahexaenoic acid (DHA), an omega-3 fatty acid

  • For everyday supplement use, follow your specific product's label, since DHA/EPA content and recommended dose vary widely between products.
  • For the prescription-strength product, take exactly as your clinician prescribes -- typically 4 g per day, as capsules swallowed whole (not broken, crushed, or chewed), with meals.
  • Do not assume a higher dose of an everyday supplement is equivalent to, or a substitute for, the specific prescription product's medically supervised dose and monitoring.
(2) (3) (4)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7)

Missed dose

For everyday supplement use, follow your product's label or simply resume your normal schedule. For the prescription-strength product, contact your prescriber or pharmacist for guidance rather than taking an extra dose.

Overdose

Very high intakes of omega-3 (well above typical supplement or even prescription doses) have been associated with an increased bleeding risk. Seek medical advice if you have taken significantly more than intended, especially if you are also taking a blood-thinning medicine. (7)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Fishy aftertaste, burping (eructation), or mild indigestion (dyspepsia) -- more common with fish-oil-based products.

What to notice: Fishy aftertaste, burping (eructation), or mild indigestion (dyspepsia) -- more common with fish-oil-based products.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Mild gastrointestinal upset such as loose stools or nausea, especially at higher doses.

What to notice: Mild gastrointestinal upset such as loose stools or nausea, especially at higher doses.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

With the prescription-strength product specifically: constipation, taste changes, and mild increases in liver enzymes (ALT/AST) have been reported.

What to notice: With the prescription-strength product specifically: constipation, taste changes, and mild increases in liver enzymes (ALT/AST) have been reported.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Serious warnings

Signs of unusual bleeding or bruising — moderate to serious

Symptoms: Unusual bruising, nosebleeds, bleeding gums, or blood in stool or urine.

Action: Contact your clinician, particularly if you take an anticoagulant (such as warfarin) or antiplatelet medicine, or if you are taking a high dose of any omega-3 product -- omega-3 fatty acids can affect bleeding time. (2) (7)

New or worsening irregular heartbeat (with the prescription-strength product) — serious

Symptoms: Palpitations, a racing or irregular heartbeat, dizziness, or shortness of breath, particularly in the first two to three months of starting the prescription-strength product.

Action: Contact your clinician promptly -- the prescription-strength EPA+DHA product has been associated with a possible increase in recurrent atrial fibrillation or flutter episodes in people who already have this condition. (2)

Signs of a serious allergic reaction — emergency

Symptoms: Swelling of the face, lips, tongue, or throat; difficulty breathing; widespread rash or hives, especially in people with a fish or shellfish allergy.

Action: Seek emergency medical help immediately, and let the clinician you see advise on whether to continue or stop the product. (2)

Interactions

  • Anticoagulant medicines (such as warfarin) or antiplatelet medicines: omega-3 fatty acids, especially at higher/prescription doses, can add to bleeding risk -- periodic monitoring is advised. (2) (7)
  • No clinically significant interaction was found between the prescription-strength product and common statins (simvastatin, atorvastatin, rosuvastatin) in the sources reviewed. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

DHA is a normal dietary nutrient and is included in some prenatal supplements; discuss the specific product and dose with your midwife or clinician. For the prescription-strength product specifically, human data are insufficient to determine risk, though animal studies at high doses showed no adverse developmental effects. (1) (2) (3) (4) (5) (6) (7)

Breastfeeding

DHA is a normal component of breast milk. EPA and DHA from supplements or the prescription-strength product also pass into breast milk; discuss your specific product and dose with your clinician. (1) (2) (3) (4) (5) (6) (7)

Children

DHA is a normal dietary nutrient, and the EU has an authorised claim for DHA supporting normal brain development in children aged 12 months to 12 years at 250 mg/day. The prescription-strength product's safety and effectiveness in children have not been established. (1) (2) (3) (4) (5) (6) (7)

Elderly

No specific everyday-supplement dose adjustment based on age alone is described in the sources reviewed; the prescription-strength product showed similar safety/efficacy in trial participants over 65 compared with younger adults, though enrollment of this group was limited. (1) (2) (3) (4) (5) (6) (7)

Hepatic_impairment

For the prescription-strength product, periodic liver function (ALT/AST) monitoring is recommended, since some patients show isolated liver enzyme elevation. (1) (2) (3) (4) (5) (6) (7)

Renal_impairment

No specific renal-impairment dosing guidance was identified in the sources reviewed for either the everyday supplement or the prescription-strength product. (1) (2) (3) (4) (5) (6) (7)

Monitoring

Before starting

  • Review of current anticoagulant/antiplatelet medicines
  • Assessment of fish/shellfish allergy status
  • For the prescription-strength product: baseline liver function and lipid panel

During treatment

  • Periodic lipid panel monitoring for the prescription-strength product, including LDL cholesterol (which may rise)
  • Periodic liver function tests (ALT/AST) for the prescription-strength product
  • Ongoing awareness of bleeding-risk symptoms, especially at high supplement doses or when combined with anticoagulants
  • Awareness of palpitations or irregular heartbeat, particularly in the first 2-3 months of the prescription-strength product in people with a history of atrial fibrillation/flutter
(2)

Storage

Store at room temperature (typically 15-30C / 59-86F), away from heat and light, and do not freeze. Keep out of reach of children. Follow your specific product's label for exact storage conditions.

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information for Lovaza and the UK EMC SmPC for Omacor; verify against the current full label before prescribing the prescription-strength product, and note that everyday DHA supplements are not medicine-regulated products.

United States

Indication: Severe hypertriglyceridaemia (>=500 mg/dL), prescription-strength product only

Dose summary: 4 g/day (one 4 g dose or two 2 g doses) of omega-3-acid ethyl esters (~465 mg EPA + ~375 mg DHA per 1 g capsule).

Renal context: No specific renal dosing guidance identified in the sources reviewed. (2)

United Kingdom / Australia

Indication: Endogenous hypertriglyceridaemia (and, in Australia, also post-MI secondary prevention), prescription-strength product only

Dose summary: 2-4 capsules daily (840 mg omega-3-acid ethyl esters per capsule: ~460 mg EPA + ~380 mg DHA).

Renal context: No specific renal dosing guidance identified in the sources reviewed. (3) (6)

Mechanism of action

Hepatic guidance

Periodic ALT/AST monitoring recommended for the prescription-strength product; some patients show isolated ALT elevation without a corresponding AST rise.

Overdose note

No specific antidote information identified for the prescription-strength product in the sources reviewed; very high omega-3 intakes are associated with increased bleeding risk. (2) (3)

Frequently asked questions

Is DHA/omega-3 an FDA-approved medicine?

As an everyday supplement, no -- DHA is regulated in the United States as a dietary supplement under DSHEA, which does not require FDA pre-market approval and does not permit disease-treatment claims (though a qualified health claim for heart health exists). Separately, a specific high-dose prescription combination of EPA and DHA (Lovaza) IS an FDA-approved medicine, but only for severe hypertriglyceridaemia -- these are two different things. (1) (2)

Is DHA regulated the same way in every country?

The everyday-supplement pathway (not requiring medicine-style pre-approval) is confirmed across the United States, United Kingdom, European Union, Canada, Australia, and New Zealand, though the specific regulatory framework differs by name (DSHEA in the US, EFSA health-claims regulation in the EU, Health Canada's Natural Health Products/NPN system in Canada, TGA-listed AUST L complementary medicines in Australia, and the Dietary Supplements Regulations 1985 in New Zealand). The separate prescription-strength product is confirmed medicine-approved in the US, UK, and Australia; no equivalent Canadian or New Zealand prescription product was found in the sources reviewed for this dossier. (1) (4) (5) (6) (7)

Can I take a high dose of an everyday DHA supplement instead of the prescription product for high triglycerides?

No. The prescription-strength product's triglyceride-lowering effect was demonstrated at a specific, medically supervised 4 g/day dose of a particular EPA+DHA ethyl ester formulation, with monitoring for LDL cholesterol, liver enzymes, and heart rhythm. An everyday over-the-counter supplement has not gone through this same medicine-approval process for this use, and self-substituting is not a safe or supported approach -- speak with your clinician about high triglycerides instead. (2)

What is the mechanism of action of docosahexaenoic acid (DHA), an omega-3 fatty acid?

DHA and EPA are long-chain omega-3 polyunsaturated fatty acids. At prescription-strength doses, proposed triglyceride-lowering mechanisms include inhibition of hepatic acyl-CoA:1,2-diacylglycerol acyltransferase, increased hepatic mitochondrial/peroxisomal beta-oxidation, decreased hepatic lipogenesis, and increased plasma lipoprotein lipase activity, resulting in reduced VLDL and triglyceride synthesis. (2) (3)

What is the generic name of DHA (docosahexaenoic acid)?

The generic name is docosahexaenoic acid (DHA), an omega-3 fatty acid. It is sold under brand names including Sold under many different dietary-supplement brand names; the prescription-strength EPA+DHA combination product is branded Lovaza (United States) or Omacor (United Kingdom, Australia). (1) (2)

What class of drug is docosahexaenoic acid (DHA), an omega-3 fatty acid?

DHA (docosahexaenoic acid) is classed as: Omega-3 fatty acid; dietary/natural-health supplement, or (specific prescription-strength combination products only) a licensed medicine for severe/endogenous hypertriglyceridaemia. (1) (2)

References

  1. FDA qualified health claims for EPA and DHA omega-3 consumption and risk of hypertension/coronary heart disease; DSHEA dietary supplement frameworkU.S. Food and Drug Administration (FDA) -- dietary supplement/food-labeling regulatory guidance · United States · accessed 2026-07-30 · source 1
  2. LOVAZA (omega-3-acid ethyl esters) capsules -- full prescribing informationDailyMed (U.S. National Library of Medicine) -- FDA prescribing information · United States · accessed 2026-07-30 · source 2
  3. Omacor 1000 mg Soft Capsules -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · accessed 2026-07-30 · source 3
  4. EU Register of nutrition and health claims made on foods -- EPA/DHA entriesEuropean Food Safety Authority (EFSA) -- authorised nutrition and health claims under Regulation (EC) No 1924/2006 · European Union · accessed 2026-07-30 · source 4
  5. NutraSea ADHD (fish oil, EPA/DHA) -- Natural Health Product Licence (NPN 80094538)Health Canada -- Licensed Natural Health Products Database (LNHPD) / Natural and Non-prescription Health Products Directorate (NNHPD) · Canada · accessed 2026-07-30 · source 5
  6. Omega-3 Fish Oil 1000 (ARTG 333464, AUST L listed complementary medicine); OMACOR omega-3-acid ethyl esters 90 1000mg soft capsule (ARTG 155717, AUST R registered prescription medicine)Therapeutic Goods Administration (TGA), Australia -- ARTG listed (complementary medicine) and registered (prescription medicine) entries · Australia · accessed 2026-07-30 · source 6
  7. Omega-3 and fish oil supplements -- Healthify medicines A-Z; Medsafe Dietary Supplements Regulations guidanceHealthify (Te Whatu Ora / Health New Zealand-funded national health information service); Medsafe dietary supplement regulatory guidance · New Zealand · accessed 2026-07-30 · source 7

Brand names by country

Single-ingredient docosahexaenoic acid (DHA), an omega-3 fatty acid names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • DHA (generic dietary supplement) (1)DSHEA dietary supplement no premarket approval required · varies by product · multiple manufacturers
  • Lovaza (prescription omega-3-acid ethyl esters) (2)FDA approved 2004 severe hypertriglyceridaemia · 1 g capsule (~465 mg EPA, ~375 mg DHA) · GlaxoSmithKline (originator); multiple generic manufacturers

United Kingdom

  • Omacor (prescription omega-3-acid ethyl esters) (3)MHRA licensed confirmed via EMC SmPC · 1000 mg soft capsule (~460 mg EPA, ~380 mg DHA) · multiple

Canada

  • NutraSea ADHD (representative licensed NHP example) (5)Health Canada NNHPD NPN licensed confirmed · fish oil 3.6 g (580 mg EPA, 360 mg DHA) per serving · Nature's Way of Canada Ltd.

Australia

  • Omega-3 Fish Oil 1000 (representative AUST L listed example) (6)TGA ARTG listed complementary medicine confirmed · varies by product · multiple manufacturers
  • Omacor (prescription omega-3-acid ethyl esters 90) (6)TGA ARTG registered prescription 2010-07-28 · 1000 mg soft capsule · Arrotex Pharmaceuticals Pty Ltd

New Zealand

  • Omega-3/fish oil supplements (general category, Dietary Supplements Regulations 1985) (7)Healthify confirmed supplement no medsafe premarket approval required · varies by product · multiple manufacturers
View brands in additional countries.

European Union

DHA (food supplement, EFSA-regulated health claims) (4)