Omega-3 supplements are generally safe, and most individuals have no side effects. Some individuals may experience mild side effects such as an upset stomach, which can be minimized by taking Omega-3 supplements with meals or choosing high-quality supplements that are less likely to cause gastrointestinal discomfort. As with any supplement, it's important to consult with a healthcare professional if you are taking blood thinners, anticipating surgery, or have a known medical condition.