Written by Karen Pilkington and the CAM-Cancer Consortium.
Updated February 28, 2017

Spirulina (blue-green algae)

Is it safe?

Adverse events

Few adverse effects are caused by good quality blue-green algae products (see Warnings).3 Contamination has been reported of some spirulina products which will affect the products’ safety. A recent review of safety by the US Pharmacopeia Dietary Supplements Information Expert Committee considered a total of 31 adverse events reported in relation to spirulina.21 Side effects reported in clinical trials include gastro-intestinal problems such as diarrhoea and flatulence.3 Headaches and general muscular aches were reported by some patients in one trial although it uncertain whether these were due to spirulina.5 One case of anaphylaxis 22 and one of acute rhabdomyolysis have also been reported.23 The latter resolved after discontinuation of the supplement.


There is a lack of reliable information on safety in pregnancy or breast-feeding.3 Long-term use of Spirulina supplements by the mother was found to be related to hypercalcaemia in a newborn baby who developed generalised seizures.24


There is a theoretical interaction between blue-green algae and immunosuppressant drugs due to the possible immune-stimulating effects of the algae.3


Blue-green algae products have been found to be contaminated with potent toxins known as microcystins.3,9 Contamination may be more likely for algae grown in natural settings rather than under controlled conditions as is usually the case for commercially available spirulina products.3 Microcystins can cause hepatotoxicity, nephrotoxicity and neurotoxicity 9 which may be fatal, particularly in children who are more sensitive to the toxic effects.3 Symptoms of poisoning including abdominal pain and distention, nausea, vomiting, weakness, excessive thirst, rapid and weak pulse and shock, generally occur between 30 minutes and 24 hours after ingestion.3 Recent toxicology studies found some blue-algae products available in Germany and Italy to be contaminated but the affected products were those containing a species other than spirulina.25,26 It has been recommended that products should be certified to be free of contamination.9

Citation Karen Pilkington, CAM-Cancer Consortium. Spirulina (blue-green algae) [online document]. http://ws.cam-cancer.org/The-Summaries/Herbal-products/Spirulina-blue-green-algae. February 28, 2017.


  1. Khan Z, Bhadouria P and Bisen PS. Nutritional and Therapeutic Potential of Spirulina. Current Pharmaceutical Biotechnology, 2005, 6, 373-379.
  2. Karkos PD, Leong SC, Karkos CD, Sivaji N, Assimakopoulos DA. Spirulina in clinical practice: evidence-based human applications. Evidence-based Complementary and Alternative Medicine : ECAM [2011, 2011:531053]
  3. Natural Medicines Comprehensive Database: professional version. Blue green algae monograph. Stockton (CA): Therapeutic Research Faculty. Available at: http://naturaldatabase.therapeuticresearch.com. Accessed: 28th February 2017.
  4. University of Maryland Medical Center (UMMC). Complementary medicine: Spirulina 2011. Available at: http://www.umm.edu/altmed/articles/spirulina-000327.htm. Accessed 28th February 2017.
  5. Mathew, B., R. Sankaranarayanan, P. P. Nair, C. Varghese, T. Somanathan, B. P. Amma, N. S. Amma and M. K. Nair. Evaluation of chemoprevention of oral cancer with Spirulina fusiformis. Nutrition and Cancer 1995 24: 197-202
  6. Nielsen, C. H., P. Balachandran, O. Christensen, N. D. Pugh, H. Tamta, K. J. Sufka, X. Wu, A. Walsted, M. Schjorring-Thyssen, C. Enevold and D. S. Pasco. Enhancement of natural killer cell activity in healthy subjects by Immulina(R), a Spirulina extract enriched for Braun-type lipoproteins. Planta Med 2010 76(16): 1802-1808
  7. Ciferri O. Spirulina, the edible microorganism. Microbiol Rev. 1983 December; 47(4): 551–578. PMCID: PMC283708
  8. Clark S. Astronauts to enjoy a bespoke Martian menu. New Scientist 17 June 2005. Available at: http://www.newscientist.com/article/dn7534-astronauts-to-enjoy-a-bespoke-martian-menu.html. Accessed 28th February 2017.
  9. Memorial Sloan-Kettering Cancer Center. Integrative medicine: Blue-green algae. Available at: http://www.mskcc.org/cancer-care/herb/blue-green-algae. Accessed: 28th February 2017.
  10. Hirahashi, T., M. Matsumoto, K. Hazeki, Y. Saeki, M. Ui and T. Seya. Activation of the human innate immune system by Spirulina: augmentation of interferon production and NK cytotoxicity by oral administration of hot water extract of Spirulina platensis. Int Immunopharmacol. 2002 2(4): 423-434.
  11. Lobner, M., A. Walsted, R. Larsen, K. Bendtzen and C. H. Nielsen. Enhancement of human adaptive immune responses by administration of a high-molecular-weight polysaccharide extract from the cyanobacterium Arthrospira platensis. J Med Food 2008 11(2): 313-322.
  12. Bhattacharyya, S. and P. Mehta. The hepatoprotective potential of Spirulina and vitamin C supplemention in cisplatin toxicity. Food Funct. 2012 3(2): 164-169.
  13. Khan, M., J. C. Shobha, I. K. Mohan, M. U. Naidu, C. Sundaram, S. Singh, P. Kuppusamy and V. K. Kutala. Protective effect of Spirulina against doxorubicin-induced cardiotoxicity. Phytother.Res 2005 19(12): 1030-1037.
  14. Mohan, I. K., M. Khan, J. C. Shobha, M. U. Naidu, A. Prayag, P. Kuppusamy and V. K. Kutala. Protection against cisplatin-induced nephrotoxicity by Spirulina in rats. Cancer Chemother.Pharmacol. 2006 58(6): 802-808.
  15. Molassiotis A, Fernandez-Ortega P, Pud D, Ozden G, Platin N, Hummerston S, Scott JA, Panteli V, Gudmundsdottir G, Selvekerova S, Patiraki E, Kearney N. Complementary and alternative medicine use in colorectal cancer patients in seven European countries. Complement Ther Med. 2005 Dec;13(4):251-7.
  16. Molassiotis A, Panteli V, Patiraki E, Ozden G, Platin N, Madsen E, Browall M, Fernandez-Ortega P, Pud D, Margulies A. Complementary and alternative medicine use in lung cancer patients in eight European countries. Complement Ther Clin Pract. 2006 Feb;12(1):34-9. Epub 2005 Nov 14.
  17. Molassiotis A, Scott JA, Kearney N, Pud D, Magri M, Selvekerova S, Bruyns I, Fernadez-Ortega P, Panteli V, Margulies A, Gudmundsdottir G, Milovics L, Ozden G, Platin N, Patiraki E. Complementary and alternative medicine use in breast cancer patients in Europe. Support Care Cancer. 2006 Mar;14(3):260-7.
  18. Hamidah, A., Z. A. Rustam, A. M. Tamil, L. A. Zarina, Z. S. Zulkifli and R. Jamal. Prevalence and parental perceptions of complementary and alternative medicine use by children with cancer in a multi-ethnic Southeast Asian population. Pediatr.Blood Cancer 2009 52(1): 70-74.
  19. Shaharudin, S. H., S. Sulaiman, N. A. Emran, M. R. Shahril and S. N. Hussain. The use of complementary and alternative medicine among Malay breast cancer survivors. Altern Ther Health Med 2011 17(1): 50-56.
  20. European Advisory Services. The use of substances with nutritional or physiological effect other than vitamins and minerals in food supplements study undertaken for dg sanco. European commission, 2007. Available at: http://ec.europa.eu/food/safety/labelling_nutrition/supplements_en, accessed 28th February 2017.
  21. Marles RJ, Barrett ML, Barnes J, Chavez ML, Gardiner P, Ko R, Mahady GB, Low Dog T, Sarma ND, Giancaspro GI, Sharaf M, Griffiths J. United States pharmacopeia safety evaluation of spirulina.Crit Rev Food Sci Nutr. 2011 Aug;51(7):593-604.
  22. Petrus M, Culerrier R, Campistron M, Barre A, Rougé P. First case report of anaphylaxis to spirulin: identification of phycocyanin as responsible allergen. Allergy. 2010 Jul;65(7):924-5. .
  23. Mazokopakis EE, Karefilakis CM, Tsartsalis AN, Milkas AN, Ganotakis ES. Acute rhabdomyolysis caused by Spirulina (Arthrospira platensis). Phytomedicine. 2008 Jun;15(6-7):525-7. .
  24. Moulis G, Batz A, Durrieu G, Viard C, Decramer S, Montastruc JL. Severe neonatal hypercalcemia related to maternal exposure to nutritional supplement containing Spirulina. Eur J Clin Pharmacol. 2012 Feb;68(2):221-2.
  25. Heussner AH, Mazija L, Fastner J, Dietrich DR. Toxin content and cytotoxicity of algal dietary supplements. Toxicol Appl Pharmacol. 2012 Oct 12. pii: S0041-008X(12)00435-8.
  26. Vichi S, Lavorini P, Funari E, Scardala S, Testai E. Contamination by Microcystis and microcystins of blue-green algae food supplements (BGAS) on the italian market and possible risk for the exposed population. Food Chem Toxicol. 2012 Dec;50(12):4493-9.