Either along with the feeling of nausea or even without it, it is possible to have headache after having consumed wheatgrass. However, this is often attributed to the detoxification effect that the body undergoes after one has consumed a glass of juice. As the body rapidly gets rid of the toxins like heavy metals, fats and metabolic wastes in the body, one experiences headache and nausea. Once the toxins have been removed from the body the effects of nausea and headache also subside. These effects are also often, although incorrectly associated with mold in wheatgrass.