9 Spirulina Side Effects You May Experience

spirulina side effects

Article at a glance:

  • In some rare cases, spirulina may cause side effects.
  • Most of spirulina’s side effects are mild or are linked to allergies and underlying health conditions.
  • Generally, spirulina doesn’t pose any danger to healthy individuals.


Spirulina is undoubtedly one of the most popular superfoods available. Its benefits outweigh its drawbacks, but as responsible consumers, it’s important to learn of any side effects of spirulina before taking it. Here, you’ll learn more about the spirulina side effects you may encounter and know what to expect.


What Is Spirulina?


Spirulina is blue-green algae known to be one of the most nutrient-dense superfoods around. It has many health benefits when taken regularly and properly.

If you’re looking for spirulina supplements, you may find them in several forms, including spirulina tablets, spirulina powder, and liquid extracts. Like many superfood dietary supplements, you can take spirulina alone or incorporate it into your meals and drinks.


What Are the Possible Side Effects of Spirulina?


If you’re wondering what are the dangers of spirulina before you try it, know that side effects are rare because spirulina is a food supplement. As long as you follow the recommended dose, do not have allergies or an autoimmune condition, and do not take medications that may interact with spirulina, then everything should be okay.


1. Spirulina Side Effects on the Liver


Is spirulina hard on the liver?

Let’s face it, not all spirulina products are the same. Some manufacturers harvest and produce substandard supplements and put them out on the market. Some manufacturers may opt to get spirulina harvested from the wild. And when they do, they also don’t process it properly.

This may lead to a high probability of the spirulina being contaminated by heavy metals, bacteria, and other toxic particles. The supplement may also contain microcystins, a particle produced by cyanobacteria like spirulina as a defense mechanism. In high amounts, the said particle may cause damage to your liver and may impair liver function.

To avoid sub-standard spirulina products, purchasing from brands that grow them in controlled environments is best. The blue-green algae taken from such sources are lower and microcystins. Additionally, buy from certified brands to process toxins and other possible contaminants from their products.


2. Spirulina Side Effects on the Immune System


Can spirulina worsen autoimmune disorders?

Spirulina has been known to help in boosting the immune system. This blue-green algae supplement can reinforce the body’s resilience to diseases and may minimize inflammation. It does so by helping strengthen immune cells called natural killer cells.

This is good for a healthy person since spirulina can help fight diseases. However, for those suffering from autoimmune diseases, such as lupus and rheumatoid arthritis, spirulina supplementation might be a bad idea.

Reinforcing the NK cells in people suffering from autoimmune diseases may worsen their symptoms. On top of this, some studies found a link between spirulina supplements and serious autoimmune reactions for those with such conditions, albeit the cases are rare.

If you’re in good health, you don’t need to worry about this side effect of spirulina. However, avoiding spirulina and other algae supplements is best if you have autoimmune conditions.


3. Spirulina Side Effects on the Heart and Cardiovascular System


Can spirulina raise blood pressure?

Spirulina Side Effects on the Heart and Cardiovascular System


If you suffer from high blood pressure and are worried about this, you’re in luck, as spirulina has the opposite effect. It may actually help lower your blood pressure. It also helps lower LDL cholesterol levels in your system, leading to better overall cardiovascular health.

However, spirulina is said to have an effect that stops blood from coagulating. As such, spirulina may help thin your blood and cause it to clot longer than normal.

Blood clotting helps in avoiding excessive bleeding and even bruising caused by injuries. However, taking spirulina may pose a danger if you need blood thinners due to certain medical conditions or have a bleeding disorder. This supplement may weaken your blood’s clotting ability even further, which may cause more bruising and bleeding.

A few studies indicate that spirulina doesn’t affect blood clotting time, but this study is only for those who don’t take blood thinners. Little is known about its actual effects on people taking blood thinners, so to be safe, try to avoid this supplement if you have trouble with blood clotting.


4. Spirulina Side Effects on the Kidney


Is spirulina hard on the kidneys?

Everything is great in moderation, including supplements like spirulina. Having too much of a good thing can also turn bad. When it comes to spirulina, a dose considered “too much” is over 50 grams daily.

But how does this affect an individual? One is the possibility of having kidney stones. This may happen due to the supplement’s rich nucleic acid concentration, which can create uric acid once it’s metabolized. This can lead to both kidney stones and gout.

To avoid such a complication, make sure to follow the recommended doses of your spirulina supplement.


5. Spirulina Side Effects on the Digestive System


Does spirulina make you poop more?

One of the rare spirulina side effects is diarrhea. However, this is only the case for a small number of people. Some of the symptoms of diarrhea include stomach pain, digestive discomfort, loose bowel movement, nausea, and bloating. Luckily, spirulina-caused diarrhea is usually mild and non-life-threatening.


6. Spirulina Side Effects on the Thyroid


side effect of Spirulina on Thyroid


Some thyroid disorders can be aggravated by taking spirulina. The iodine content in spirulina can cause harm to people suffering from hyperthyroidism or having an overactive thyroid. Those who suffer from Hashimoto’s, which is a thyroid disorder connected to the immune system, can also suffer worse symptoms from consuming spirulina.

However, spirulina is not harmful to every type of thyroid disorder. For one, people who have thyroid nodules may benefit from it.


7. Allergies and Specific Contraindications


Allergic reactions have been linked to spirulina, but only in extremely rare cases. Most things can become an allergen for different people, including spirulina. So, if you take spirulina and experience allergic reaction symptoms, such as rashes and difficulty breathing, it’s best to seek medical attention as soon as possible.

Those allergic to seafood, shellfish, or even iodine should avoid drinking spirulina. Some studies found that those allergic to these may also be allergic to spirulina, which is a cyanobacterium, and vice versa. If you think you have an allergy but are still unsure, consult a physician who can also properly administer a sensitivity test.


8. Dangerous for Those with Phenylketonuria


An extremely rare genetic disorder called Phenylketonuria affects around 1 in 24,000 people. This disorder causes the body to fail to metabolize the amino acid phenylalanine, which is needed to form proteins, hormones, and neurotransmitters.

If a person suffers from phenylketonuria, the amino acid will build up in the body, and it may cause side effects like seizures and behavioral changes. Spirulina, along with other types of algae, contains a notable amount of this amino acid, so it should be avoided by those with this disorder.


9. Spirulina Side Effects on the Skin


woman with itchy skin


Itchy skin is a well-known side effect of spirulina tablets for a small group of people. Spirulina may help detoxify the body from harmful compounds like heavy metals and other toxins. When the toxins are flushed out of your system, they can cause temporary rashes and skin itching. Usually, though, this issue is harmless.

Do note that rashes and itchy skin are also symptoms of an allergic reaction.


Should You Still Take It? Here’s What You Might Miss


If you are healthy, taking spirulina should not be a problem. The side effects of consuming spirulina are rare. This superfood is generally well-tolerated, and it is recommended that people with specific health and medical conditions avoid it.

Here are a few of the various health benefits that this superfood can bring:

  1. It may help improve your overall cardiovascular health. Adding spirulina to your diet may help lower your systolic and diastolic blood pressure. Additionally, spirulina increases nitric oxide production in the body, which may help loosen blood vessels.
  2. It may help boost immune function. Spirulina may help increase the production of white blood cells and antibodies, making it a good immunomodulator.
  3. Spirulina consumption may help manage iron deficiency anemia.
  4. Spirulina consumption may help manage blood glucose levels. Some studies indicate that it may be as effective as well-known blood sugar medications. While more research is needed, given its performance, many say it may be a good alternative to such medication.
  5. Spirulina has anti-inflammatory properties. As such, this superfood may help with chronic inflammation and airway allergies like allergic rhinitis.
  6. It has an excellent nutritional profile. Spirulina is rich in nutrients. Many know it for providing complete protein with all the essential amino acids our body needs. It’s also rich in carotenoids, vitamins, and minerals.
  7. Spirulina may support eye health thanks to its rich beta-carotene and lutein content.
  8. Spirulina may help overall athletic performance and in losing body weight.
  9. Spirulina may help lower heavy metal toxicity and absorb other harmful substances in the body.


Frequently Asked Questions


What Happens When You Take Spirulina Every Day?


Yes, definitely. If you take the right dose daily and have no underlying medical condition that spirulina may aggravate, you will reap most of this superfood’s health benefits. The recommended daily dose is between 5 to 8 grams. Taking too much, especially significantly higher doses, may lead to unwanted side effects.


What Happens If You Take Spirulina on an Empty Stomach?


Spirulina can be taken whether you’ve eaten or have an empty stomach. In fact, this blue-green algae dietary supplement can be taken at any time of the day.


Who Should Avoid Spirulina?


Can spirulina be harmful? To some people, yes, but this is extremely rare. The side effects listed in this article are all rare since spirulina is safe to consume by most healthy individuals.

The only people who should not take spirulina supplements are the following:

  • Pregnant women
  • People who are allergic to spirulina and iodine
  • People with hyperthyroidism or Hashimoto’s
  • People with autoimmune disease
  • People with medical conditions that require them to take blood thinners
  • People with blood clotting disorders


Does Spirulina Mess with Hormones?


It’s still unclear whether spirulina can mess with hormones. Although one animal study found that spirulina platensis intra-peritoneal injections caused hormone disruption in mice, it’s still unclear whether the same effects also happen among people, as human studies regarding this are lacking.

However, spirulina contains vital nutrients like calcium, magnesium, and potassium, which help balance hormones. Studies have also found that it may help fight metabolic syndrome.


Spirulina Benefits Over Drawbacks


Microalgae spirulina does have a small number of drawbacks. However, the danger of spirulina consumption is minuscule as this is generally well tolerated. The small number of people affected by this supplement negatively usually already have health disorders to look out for.

Most of the side effects of spirulina are rare; the most “common” ones are usually harmless. As such, for healthy individuals without any underlying condition that spirulina may worsen, it’s best to look at its benefits over possible side effects.

This supplement brings a lot to the table and can affect you positively in the long run. Try out spirulina today and reap its long list of health benefits.




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John Riedl

Simply put that’s why I’ve gone down the health journey of research and creating health brands.

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