The side effects of omega 3 include stomach upset, loose stools, and nausea. Adequate intake of Omega-3 is 1.6g and 1.1g for adult males and females respectively. Excessive intake of Omega-3 has been shown to increase the risk of bleeding. Omega 3 supplements are made of common food allergen sources such as fish, nuts, and more. So those who have allergies should check the ingredient list before purchasing any product.