9 Shocking Side Effects Of Spirulina

Medically reviewed by Sarah Spann, Adv Dip (Nut Med), mATMS
by Swathi Handoo

Does the idea of taking natural supplements for an enhanced immunity interest you?

If so, you’d be shocked to learn about the other side of one such popular single cell supplement – spirulina.

Scroll down to find out how spirulina, the superfood, is harmful to you, how it introduces toxins in a healthy body, and more fatal side effects.

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What Is Spirulina?

Spirulina is free-floating filamentous microalgae growing in alkaline water bodies. Due to its high nutritional value, spirulina has been consumed as food for centuries in Central Africa.

It is now widely used as a nutraceutical food supplement worldwide. People consume spirulina orally in the form of powder, flakes, or tablets for several health benefits.

Spirulina powder and flakes are usually added to fruit juices and smoothies. It can have an adverse impact on your health if you do not take it in controlled doses. Read on to find out how.

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What Are The Potential Side Effects Of Spirulina?

1. Worsens Phenylketonuria

Phenylketonuria is a genetically acquired disorder in which the patient cannot metabolize the amino acid called phenylalanine due to the lack of an enzyme called phenylalanine hydroxylase.

The patient exhibits symptoms like delayed development, convulsions, hyperactivity, and analytical disability. Unfortunately, spirulina is a rich source of phenylalanine.

Consuming spirulina aggravates the symptoms of phenylketonuria.

2. Exacerbates The Symptoms Of Autoimmune Diseases


An autoimmune disease develops when the immune system attacks the healthy tissues in your body, causing organ damage and inflammation.

Arthritis, asthma, periodontitis, vitiligo, type 2 diabetes, multiple sclerosis, psoriasis, and pernicious anemia are a few examples of autoimmune diseases.

Spirulina is, after all, a foreign body. When you consume it, the body overreacts and amplifies the activity of the immune system. This exacerbates the symptoms of a pre-existing disease or gives rise to severe inflammation (1).

3. Interferes With Drug Action

Spirulina is an irritant to your immune system. It can interfere with drugs, especially immunosuppressants.

A person on immunosuppressant medication must not consume spirulina. Else, it will diminish the effect of the medication, resulting in serious complications.

4. Risk Of Heavy Metal Toxicity

Certain varieties of spirulina that are produced under unrestrained settings are often infested with significant traces of heavy metals, such as mercury, cadmium, arsenic, and lead.

Prolonged consumption of spirulina that comes from such undependable sources results in damage to your vital organs, such as the kidneys and liver.

Compared to adults, children are at a higher risk of developing fatal complications due to heavy metal poisoning from contaminated spirulina.

Make sure to check where your spirulina is sourced from.

5. Renal Disorders

Our body produces a significant amount of ammonia as it metabolizes the protein in spirulina, which gets converted into urea.

This puts excessive pressure on the kidneys to flush out such a large amount of urea from the blood, ultimately resulting in decreased efficiency of the kidneys and even renal failure.

Some people tend to develop kidney stones due to such high concentrations of urea in the renal system.

6. Triggers Edema And Body Weight Fluctuation

Spirulina is packed with vitamins, proteins, and minerals. People with compromised renal function would be unable to expel the unnecessary components from their bloodstream.

One of the most abundant minerals found in spirulina is iodine. While on the one hand, it is good to take in iodine via spirulina, on the other hand, it could affect your thyroid and parathyroid glands. The effects are more pronounced in people with hyperparathyroidism.

The build-up of excessive nutrients, along with iodine, in the blood leads to fluid retention (edema) in your limbs, imbalance in calcium, phosphate, and iodine absorption, and sudden weight gain or loss, lethargy, and cardiovascular diseases.

7. Digestive Discomfort And Nausea


Consuming spirulina can lead to flatulence, causing abdominal cramps, nausea, and anaphylaxis – especially in people consuming it for the first time (2).

Spirulina varieties infested with contaminants, such as microcystins (toxins produced by blue-green algae), also give rise to serious gastric ailments like acute dehydration and indigestion.

8. Could Cause Anxiety And Motor Neuron Disease (MND)

Spirulina harvested from the unrestrained wild sources, such as lakes, ponds, and littered seas, contain toxic strains.

Such morphologically similar blue-green algae produce neurotoxic chemicals like β-methylamino-L-alanine, or BMAA, which could cause severe neurodegenerative disorders like motor neuron disease (MND), amyotrophic lateral sclerosis (ALS), Alzheimer’s, Parkinson’s, dementia, anxiety, and sleepless nights (insomnia) (3).

9. Risk For Pregnant And Breastfeeding Women

The safety of spirulina for pregnant and nursing women is not well explored. Hence, it is recommended that pregnant or nursing women avoid taking spirulina or remain under strict medical surveillance while doing so.

Infants and children should be kept away from such supplements because they quickly develop allergies and fatal cross-reaction.

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In Short…

Though algae like spirulina are highly beneficial to our body, having it in the right dose matters.

Not only the dosage, but the source from which you obtain such supplements also has a significant effect on your health. It is important to know

  • the biochemical composition (co-existing microbes)
  • what kind of exhaust gets into these waters
  • whether the effluents are treated before discharge
  • the health of the local community
  • how the QC (quality control) of the source waterbody is done

To reap the maximum benefits from an excellent nutritive supplement like spirulina, you need to inquire about such details to avoid the deadly side effects listed here.

Remember always to keep your physician informed about the dosage and the way your body reacts to spirulina. In case you notice any of the symptoms we have discussed, refrain from taking spirulina and visit your doctor immediately.

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Swathi holds a Master’s degree in Biotechnology and has worked in places where actual science and research happen. Blending her love for writing with science, Swathi writes for Health and Wellness and simplifies complex topics for readers from all walks of life.And on the days she doesn’t write, she learns and performs Kathak, sings Carnatic music compositions, makes plans to travel, and obsesses over cleanliness.