Spirulina (Arthrospira platensis): Uses, Evidence and Safety

Safety first: contamination, allergy and who should ask first

Spirulina is not a land plant. It is a cyanobacterium ("blue-green alga"), and that matters for safety. A 2026 review reports that cyanotoxins, including microcystins, have been found in commercial supplements made from Arthrospira (spirulina), Aphanizomenon and Chlorella, and that these toxins can harm the liver, kidneys and nervous system. [1] The same review points out that little is known about long-term, low-level exposure. [1] The US liver-injury database LiverTox says liver injury from spirulina itself "must be very rare if it occurs at all", but notes isolated case reports in which spirulina could not be separated from other ingredients or contaminants. [2] A teenager developed anaphylaxis (a severe allergic reaction) after his first spirulina tablet, and skin testing pointed to the spirulina itself. [3] Our companion page also covers case reports of autoimmune flares and a PKU question; those were not re-checked for this page, so read spirulina and chlorella explained and autoimmune conditions and immune-stimulating products and ask a clinician if either applies to you. If you feel seriously unwell after a supplement, get medical care promptly; see liver injury warning signs. This page is information, not a recommendation.

Overview

Spirulina is the dried whole organism Arthrospira platensis (Gomont), accepted in GBIF's backbone taxonomy, which places it in the family Microcoleaceae, kingdom Bacteria. [4] An older name, Spirulina platensis, is still common on labels. Its native range was not given in the sources we read. It is sold as powder, tablets, capsules and as an ingredient in foods and drinks. This page covers Arthrospira platensis products. It does not cover chlorella (a green alga; see spirulina vs chlorella) or Aphanizomenon "blue-green algae" products, which are different organisms.

Traditional use (not proof of benefit)

LiverTox says spirulina is taken as food and for conditions such as ADHD, allergic rhinitis, high blood pressure, diabetes, stress, fatigue, anxiety and depression. [2] These are reasons people take it, not proof that it works. The sources we read did not describe a documented history of traditional medicinal use in particular cultures, so we do not describe one.

What research shows

Most studies are small, short and use different products and amounts. Several meta-analyses pool them, but the pooled trials differ a lot in size and quality.

Mood, kidney, and long-term outcomes: Proper evidence not found in the sources we read.

Forms and why the form matters

The studies used powder, tablets, or spirulina mixed into sauces, yogurt-style desserts and drinks. [5][7][12] Results differ by form: in the dessert trial, spirulina's lab effect on a blood-pressure enzyme disappeared in the food, and blood pressure did not fall. [7] Spirulina is also sold as a food colouring and in "greens" blends; those mixtures were not what the trials tested. Spirulina is also not a reliable vitamin B12 source. Laboratory analysis of commercial powders found that pseudovitamin B12, a form humans are not known to use, was the main form. [17] That study did not test absorption in people, but it is a reason not to rely on spirulina for B12 if you eat no animal foods; see vitamin B12 for vegetarians and vegans. How much to use is a decision for a clinician or pharmacist.

Safety in more detail

• Side effects: the sources we read did not give a full list of common side effects. The LactMed record says products grown in uncontrolled conditions can contain heavy metals and other contaminants. [18]
• Contamination: microcystins and other cyanotoxins have been found in commercial supplements of this kind. [1] A test of products on the Slovenian market found that 86.7% of statements about mineral content on labels were inappropriate, and called for stricter control. [19] See heavy metals in supplements and herbal products.
• Medicines: no herb-drug interaction was documented in the sources we read, which is not the same as none existing. For people with diabetes or on blood pressure medicines, trials show spirulina can lower glucose or pressure, so ask the prescriber. [5][11] See how herb and medicine interactions work.
• Autoimmune disease and transplant: not covered in the sources we read for this page; see the companion pages above. This is a reason to ask a specialist, not proof of harm.
• PKU: Proper evidence not found in the sources we read on spirulina and phenylketonuria. People with PKU should ask their metabolic dietitian before using it.
• Pregnancy: Proper evidence not found in the sources we read. See pregnancy and breastfeeding.
• Breastfeeding: LactMed says no data exist on spirulina in nursing mothers or infants. [18]
• Children: trials above studied children, mainly undernourished ones, in supervised settings. [14] Little else was read.
• Liver and kidney: LiverTox describes liver injury as very rare, with contamination or other ingredients a possible cause. [2] In rats given very high amounts for 28 days, liver and kidney damage was reported; that is animal data and does not show what happens in people. [20]
• Allergy: anaphylaxis has been reported after a spirulina tablet. [3] Stop and seek care after any swelling, breathing trouble or hives.
• Surgery: see supplements before surgery. We found no spirulina-specific guidance in the sources we read.

Official statements

• LiverTox (NIDDK/NIH), 2012 record: liver injury due to spirulina "must be very rare if it occurs at all". [2]
• LactMed (NIH), record read 2026-10-23: no data on use while breastfeeding; contaminant warning for uncontrolled production. [18]
• EU or US regulatory statements on spirulina: Proper evidence not found in the sources we read.

Related pages

• Spirulina and chlorella explained
• Spirulina vs chlorella
• Moringa
• Herbs and liver injury
• Herbs and autoimmune conditions
• Herbs for blood pressure and cholesterol: what research shows