The proper dosage of omega-3 fish oil supplements is up to 3 grams daily, states WebMD. The exact ideal dosage of omega-3 fatty acids varies depending on the reason for taking the supplement, according to Mayo Clinic.
Consuming more than 3 grams of omega-3 fish oil in one day increases the risk of bleeding, notes WebMD. Possible side effects associated with omega-3 fish oil include bad breath, nausea, loose stools and an upset stomach. It is important to speak to a doctor before taking high doses of omega-3 fish oil. In America, the average adult over the age of 18 consumes approximately 1.6 grams of omega-3 fatty acids each day, as of 2015.