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Flex Omega Benefits Side Effects

Generic Name: omega-3 polyunsaturated fatty acids

Note: This page contains information about the side effects of omega-3 polyunsaturated fatty acids. Some of the dosage forms included on this document may not apply to the brand name Flex Omega Benefits.

For the Consumer

Applies to omega-3 polyunsaturated fatty acids: oral capsule liquid filled

In addition to its needed effects, some unwanted effects may be caused by omega-3 polyunsaturated fatty acids (the active ingredient contained in Flex Omega Benefits). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking omega-3 polyunsaturated fatty acids:

Incidence not known:
  • Cough
  • difficulty swallowing
  • dizziness
  • fast heartbeat
  • hives, itching, or skin rash
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • tightness in the chest
  • unusual tiredness or weakness

Minor Side Effects

Some of the side effects that can occur with omega-3 polyunsaturated fatty acids may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Change in taste
  • diarrhea
  • difficulty having a bowel movement (stool)
  • difficulty with moving
  • fever
  • full or bloated feeling
  • headache
  • loss of taste
  • muscle aches
  • muscle pain or stiffness
  • nausea
  • pain in the joints
  • pressure in the stomach
  • sore throat
  • stuffy or runny nose
  • swelling of the abdominal or stomach area
  • unusual tiredness or weakness
  • vomiting
Less common:
  • Abdominal or stomach pain or discomfort
  • belching
  • bloated or full feeling
  • excess air or gas in the stomach

For Healthcare Professionals

Applies to omega-3 polyunsaturated fatty acids: oral capsule, oral delayed release capsule, oral kit, oral liquid, oral tablet chewable


Gastrointestinal side effects including eructation (4.9%), dyspepsia (3.1%), anorexia, constipation, dry mouth, dysphagia, colitis, fecal incontinence, gastritis, gastroenteritis, gastrointestinal disorder, increased appetite, intestinal obstruction, melena, pancreatitis, tenesmus, and vomiting have been reported.[Ref]


General side effects including infection (4.4%), flu syndrome (3.5%), back pain (2.2%), pain (1.8%), enlarged abdomen, asthenia, body odor, chest pains, chills, suicide, fever, generalized edema, fungal infection, malaise, neck pain, sudden death, and viral infection have been reported.[Ref]


Other side effects including taste perversion (2.7%) and lymphadenopathy have been reported.[Ref]


Dermatologic side effects including rashes (1.8%), alopecia, eczema, pruritus, and sweating have been reported.[Ref]


One study concluded that omega-3 fatty acid supplementation reduced heart rate and QRS duration in heart transplant recipients who were presumably devoid of vagal intervention. These findings suggest that omega-3 fatty acids may modify the electrophysiologic properties of the myocardium itself.[Ref]

Cardiovascular side effects including angina pectoris (1.3%), arrhythmia, bypass surgery, cardiac arrest, hyperlipidemia, hypertension, migraine, myocardial infarct, myocardial ischemia, occlusion, peripheral vascular disorder, syncope, and tachycardia have been reported.[Ref]


Musculoskeletal side effects including rheumatoid arthritis, arthralgia, arthritis, myalgia, pathological fracture, and tendon disorder have been reported.[Ref]


Metabolic side effects including edema, hyperglycemia, increased ALT and increased AST have been reported.[Ref]

Nervous system

Nervous system side effects including depression, dizziness, emotional lability, facial paralysis, insomnia, vasodilation, and vertigo have been reported.[Ref]


Respiratory side effects including asthma, bronchitis, increased cough, dyspnea, epistaxis, laryngitis, pharyngitis, pneumonia, rhinitis, and sinusitis have been reported.[Ref]


Genitourinary side effects including cervical disorder, endometrial carcinoma, epididymitis, and impotence have been reported.[Ref]


Hypersensitivity side effects including anaphylactic reaction have been reported.


Oncologic side effects including neoplasm and central nervous system neoplasia have been reported.[Ref]


Ocular side effects including cataract have been reported.[Ref]


Hematologic side effects including hemorrhagic diathesis have been reported.


1. "Product Information. Omacor (omega-3 polyunsaturated fatty acids)." Abbott Pharmaceutical, Abbott Park, IL.

2. "Product Information. Sea-Omega 30 (omega-3 polyunsaturated fatty acids)." Watson Pharmaceuticals, Corona, CA.

3. Harris WS, Gonzales M, Laney N, Sastre A, Borkon AM "Effects of omega-3 Fatty acids on heart rate in cardiac transplant recipients." Am J Cardiol 98 (2006): 1393-5

Not all side effects for Flex Omega Benefits may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.