Spirulina

Arthrospira platensis · Spirulina platensis · Arthrospira

Snapshot

Indications	Contraindications
Blood pressure^{1, 2} Body weight³ Blood lipids⁴ Sleep quality⁵	Pregnancy⁶ Lactation⁶

Spirulina (Arthrospira platensis) is a blue-green cyanobacterium sold as a food supplement, with antioxidant and anti-inflammatory activity attributed to pigments such as phycocyanin⁷. Supplementation is used for cardiometabolic risk factors, including blood pressure, blood lipids, and body weight. It is also used for systemic inflammation, iron status, and recovery from exhaustive exercise.

Meta-analyses of randomized trials found lower blood pressure and body weight⁴. The blood pressure effect was small and of uncertain clinical significance, and this review found no significant effect on blood lipids⁸. A smaller trial in adults with depression reported better sleep quality⁵. In outpatients with early coronavirus disease 2019 (COVID-19), a 2024 randomized trial found spirulina did not reduce hospitalization compared with placebo⁹. Products listing spirulina are mostly capsules, tablets, and powders; see Form comparison.

Contamination is the main product concern: cyanotoxins and heavy metals have been reported in spirulina products¹⁰. LiverTox rates spirulina a possible rare cause of clinically apparent liver injury, with contamination by other cyanobacteria as one proposed explanation¹¹. Health Canada labels ask for a practitioner's advice before use in pregnancy or breastfeeding¹².

Last updated October 15, 2026. Read how we make monographs.

In the full monograph

61 sources, 53 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources