Mild side effects of spirulina such as stomach pain, nausea and vomiting may subside over time, but severe side effects such as liver damage can be irreversible, explains WebMD. Spirulina products contaminated with microcystins, toxic metals and harmful bacteria are most likely to cause side effects.
Spirulina, or blue-green algae, consists of many plant-like organisms that are found in salt water and some large freshwater lakes, notes WebMD. The conditions of the environment, such as altitude, temperature and sun exposure, influence the types of blue-green algae that grow naturally in a body of water. The algae concentration can give a body of water a dark green hue. Spirulina products are grown in controlled or natural settings. Products grown in a natural setting are more likely to be contaminated with bacteria, liver poisons and heavy metals. When purchasing blue-green algae products, make sure the product has been tested and is free of contaminates.
Spirulina is used to treat numerous conditions such as attention deficit-hyperactivity disorder, premenstrual syndrome, stress, anxiety and fatigue, states WebMD. There is insufficient evidence that the alga has any demonstrable effects on these conditions. Some research shows that spirulina used for weight loss and treating precancerous mouth lesions can be effective.