Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is found along with eicosapentaenoic acid (EPA) in cold-water fish, including tuna and salmon.

DHA plays a key role in the development of eye and nerve tissues. DHA might also reduce the risk of heart and circulatory disease by decreasing the thickness of the blood, reducing swelling (inflammation), and lowering blood levels of triglycerides.

People commonly use DHA for high levels of cholesterol or other fats in the blood. It is also used for boosting memory and thinking skills, for helping infant and child development, for certain eye disorders, and many other conditions, but there is no good scientific evidence to support many of these uses.

Don't confuse DHA with EPA. They are both in fish oil, but they are not the same. DHA can be converted into EPA in the body in very small amounts. See separate listings for algal oil, cod liver oil, fish oil, EPA, and krill oil.

How does it work ?

Uses & Effectiveness ?

Possibly Effective for

  • High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). Taking DHA with or without eicosapentaenoic acid (EPA) by mouth daily seems to somewhat lower triglyceride levels. But it doesn't seem to lower total cholesterol and might increase low-density lipoprotein (LDL or "bad") cholesterol.
  • Preterm birth. Taking DHA by mouth during pregnancy seems to lower the risk of having a baby very early.

Possibly Ineffective for

  • Decline in memory and thinking skills that occurs normally with age. Taking DHA supplements by mouth alone or with other ingredients doesn't improve memory, forgetfulness, or learning ability in people with age-related memory changes.
  • Alzheimer disease. People who get more DHA from their diet might have a lower risk of Alzheimer disease. But taking DHA supplements by mouth doesn't seem to slow the progression of the disease.
  • Attention deficit-hyperactivity disorder (ADHD). Taking DHA supplements by mouth doesn't seem to improve ADHD symptoms in children.
  • A lung disease that affects newborns (bronchopulmonary dysplasia). Giving DHA to preterm infants by mouth or taking DHA by mouth while breast-feeding doesn't reduce the infant's risk for this lung disease. In fact, DHA might increase the risk for this disease in some infants.
  • Memory and thinking skills (cognitive function). Taking DHA supplements by mouth doesn't improve mental performance in healthy adults.
  • Cystic fibrosis. Taking DHA supplements by mouth doesn't improve symptoms of cystic fibrosis.
  • Depression. Taking DHA supplements by mouth doesn't seem to improve symptoms of depression or prevent depression in most people.
  • Infants born weighing more than 4000 grams (8 pounds, 13.1 ounces). Taking DHA supplements by mouth during pregnancy doesn't seem to reduce the chance of having a large baby.
There is interest in using DHA for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: DHA is likely safe for most people. It's been used safely for up to 4 years. Most side effects are mild and involve stomach and intestine issues. But people shouldn't take more than 3 grams of DHA or other omega-3 fatty acids daily, and no more than 2 grams daily should come from a dietary supplement. Taking more than 3 grams daily of DHA and other omega-3 fatty acids is possibly unsafe. Doing so might slow blood clotting and increase the chance of bleeding.

Special Precautions and Warnings

Pregnancy and breast-feeding: DHA is likely safe when taken by mouth in appropriate amounts during pregnancy and breast-feeding. DHA is commonly used during pregnancy and is an ingredient in some prenatal vitamins. DHA is also a normal part of breast milk and added to some infant formulas. It's recommended that 200-300 mg of DHA are consumed daily during pregnancy and breast-feeding, either from supplements or food sources.

Children: DHA is likely safe when used appropriately. DHA is included in some infant formulas. Also, DHA has been safely given to children 7 years and older at doses of 30 mg/kg daily for up to 4 years. It has also been safely given to children 4 years and older at doses of 0.4-1 gram daily for up to 1 year. But DHA is possibly unsafe when used in preterm infants born at less than 29 weeks. It might worsen breathing in these infants.

Diabetes: DHA seems to increase blood sugar in some people with type 2 diabetes.

Interactions ?

    Moderate Interaction

    Be cautious with this combination

  • Medications for high blood pressure (Antihypertensive drugs) interacts with DOCOSAHEXAENOIC ACID (DHA)

    DHA might lower blood pressure. Taking DHA along with medications that lower blood pressure might cause blood pressure to go too low. Monitor your blood pressure closely.

  • Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with DOCOSAHEXAENOIC ACID (DHA)

    Taking DHA might slow blood clotting. Taking DHA along with medications that also slow blood clotting might increase the risk of bruising and bleeding.

  • Medications for diabetes (Antidiabetes drugs) interacts with DOCOSAHEXAENOIC ACID (DHA)

    DHA might increase blood sugar levels. Taking DHA along with diabetes medications might reduce the effects of these medications. Monitor your blood sugar closely.


DHA is commonly consumed in the diet. Sources include cold-water fish, including mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, and seal blubber.

In supplements, DHA has most often been used by adults in doses of 400-800 mg by mouth daily for up to 6 months.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version. © Therapeutic Research Faculty 2018.