Since there is a lot of fiber in flaxseed, side effects associated with digestion may occur with various flaxseed products, including indigestion or heartburn, bloating, and gas. In most cases, these side effects are simply minor but bothersome. However, it is possible to develop serious flaxseed side effects that require medical attention, such as severe constipation or an intestinal blockage, bleeding, or an allergic reaction.
(Click Flaxseed Side Effects for a more detailed list of possible digestive problems that may occur with flaxseed, along with potentially serious side effects that may be a sign that you need to stop taking flaxseed.)