Fibromyalgia is a chronic condition characterized by pain in the muscles, ligaments and tendons, fatigue and multiple tender points on the body of unknown etiology. While available therapy is often disappointing, most patients can be helped with a combination of medication, exercise and maintaining a regular sleep schedule.

Chlorella supplementation in patients with fibromyalgia has been evaluated in clinical studies. For example, Merchant et al. (2000) evaluated the benefits of Chlorella pyrenoidosa in participants who suffer moderate to severe fibromyalgia, consuming 10 g or 100 ml of Chlorella daily for two months. The results of this study suggest that dietary supplementation with Chlorella can help relieve the symptoms of fibromyalgia, as they found a decrease in pain by 22%.