Spirulina dosage: how much spirulina per day?

Short answer: There is no official recommended amount of spirulina per day, so you follow the label. Our spirulina tablets say 3 tablets of 500 mg twice a day: 3 grams of spirulina per day in total. In randomised studies, adults usually took 1 to 8 grams per day, and according to the French food safety agency ANSES, spirulina does not appear to pose a health risk for adults at up to a few grams per day, as long as the product is not contaminated.

Last updated: 5 November 2026 · Written by Florian Fermin

How much spirulina per day is enough, and when is it too much? The right spirulina dosage depends on the form you use. Tablets, powder and a mix with chlorella each have their own directions for use. Below I list the directions for each product, convert the tablets to grams, show which amounts have been used in research and explain when it is better to take less.

What spirulina is, what it contains and what to look for when buying it is covered in our in-depth article what is spirulina.

How much spirulina per day?

Do not take more than the daily dose on the packaging of your product. Unlike vitamins and minerals, spirulina has no official recommended daily amount. The label is your guide, and it differs per product.

The milligrams per tablet come from our labels. I calculated the grams per day and the number of days from those.

How many spirulina tablets per day?

Of our spirulina tablets you take 6 a day: 3 with one meal and 3 with another, with a glass of water. Each tablet contains 500 mg of spirulina, so that adds up to 3 grams.

If you use tablets from another brand, first check how many milligrams each tablet contains. This differs per brand, so 6 tablets are not the same everywhere. This is how you convert it:

1. Find the number of milligrams of spirulina per tablet on the label.
2. Multiply that by the number of tablets per day. For ours: 6 x 500 mg = 3,000 mg.
3. Divide by 1,000 to get grams: 3,000 mg is 3 g.
4. Divide the number of tablets in the pack by the number per day: 300 / 6 = 50 days.

Not sure whether to choose tablets or powder? In spirulina tablets or powder I compare the two side by side.

How much spirulina powder per day?

Our spirulina powder says: "Take 2 scoops 2 to 3 times a day. Preferably during or just after a meal." How many grams that is depends on how full you make the scoop. If you want to know exactly, weigh a scoop once on a kitchen scale. Then you also know how long the 150 gram pouch will last.

You don't have to start with the full daily dose straight away. Taking less than the label says is always fine. Personally, I would start with one moment a day and see how your stomach reacts. That is my own advice, not a rule from the label.

If you want to know exactly how many grams of spirulina you get, tablets are easier: you know that 6 of them are 3 grams.

How much spirulina has been used in research?

In randomised studies in adults, the amount was usually between 1 and 8 grams of spirulina per day, for 2 to 16 weeks. There is little research that lasted longer.

• A meta-analysis of 5 randomised studies with 230 adults in total: 1 to 8 grams per day, for 2 to 12 weeks (Machowiec et al., 2021).
• A meta-analysis of 8 randomised studies in adults: 1 to 8 grams per day, for 3 to 16 weeks (Hariri et al., 2026).

These studies measured specific blood values. I am deliberately leaving out what they found: no health claims have been authorised for spirulina in the EU. I only mention them to show which amounts have been studied. They were small, short studies, so they say little about daily use over many years.

The 3 grams in our tablets fall within that range. ANSES writes that spirulina does not appear to pose a health risk at low doses, up to a few grams per day for adults, provided the product is not contaminated with algal toxins, bacteria or heavy metals (ANSES, 2017).

When should you take spirulina?

Take spirulina during or just after a meal, as our packaging says. The best time of day, morning or evening, has not been studied. So choose what fits your day.

• Split it over 2 moments: the label says twice a day, for example with breakfast and with dinner.
• With water: swallow tablets with a glass of water.
• Forgot a dose? Simply take the next portion at the next moment. Don't take a double amount to catch up.
• Every day: the directions are meant per day. The label does not mention a fixed course length.

Combining spirulina with chlorella or greens: how do you add it up?

If you use several products containing spirulina, add up the spirulina and stay within the daily dose on the label of each product. At GOYU, spirulina is in more than one product:

• Spirulina Chlorella Tablets: 250 mg of spirulina and 250 mg of chlorella per tablet. At 6 tablets a day that is 1.5 g of spirulina.
• Chlorella & Spirulina Combo Deal: one pack of spirulina tablets and one pack of chlorella tablets. If you follow the label for both, that is 3 g of spirulina and 3 g of chlorella per day.
• Daily Greens: contains 4% spirulina. One 8 g scoop therefore provides about 0.3 g of spirulina (calculated).

If you take, for example, our spirulina tablets and one scoop of Daily Greens, you end up at about 3.3 grams of spirulina per day. Whether spirulina and chlorella together make sense and how they differ is explained in spirulina vs chlorella. What else is in Daily Greens is covered in greens powder: what's in it.

Can you take too much spirulina?

Yes. More is not better, and the more you take, the higher the chance of complaints. The product page of our tablets states that some people get stomach problems and diarrhoea when they take a lot of spirulina. In reports about spirulina, ANSES mentions digestive complaints and allergic reactions, among others, and writes that the amounts taken were usually not known precisely (ANSES, 2017).

If you get complaints, take less or stop, and see your GP if they don't go away. All described side effects and who should be careful are listed in spirulina side effects.

Who should take less or talk to a doctor first?

Talk to your GP or pharmacist first if you are pregnant, breastfeeding, taking medication or have a medical condition. Our packaging says so too. In addition:

• Children: our spirulina powder states that mineral supplementation in infants and young children up to 3 years should take place under medical supervision. We do not give a dosage for children.
• Smoking: our spirulina powder and the Spirulina Chlorella Tablets state that they contain beta-carotene, which is not recommended for smokers.
• PKU or a tendency to allergies: ANSES advises against spirulina in that case.
• Autoimmune condition, gout or kidney stones: the product page of our tablets advises against use in these cases, as well as with an algae allergy and during pregnancy and breastfeeding.

Summary in 3 points

• There is no official daily amount for spirulina. Our tablets say 3 tablets twice a day (3 g), our powder 2 scoops 2 to 3 times a day.
• In studies, adults usually took 1 to 8 grams per day for 2 to 16 weeks. According to ANSES, up to a few grams per day does not appear to pose a risk for adults if the product is clean.
• Add up the spirulina from different products, feel free to start lower and talk to a doctor first if you are pregnant, take medication, have PKU or an autoimmune condition.

Frequently asked questions

How many grams of spirulina per day?

There is no official amount. Our tablets say 6 tablets of 500 mg per day, 3 grams in total. In studies, adults usually took 1 to 8 grams per day. Do not exceed the daily dose of your product.

How many spirulina tablets per day?

For our 500 mg tablets, that is 3 tablets twice a day, with water and with a meal. That is 6 tablets per day, and a pack of 300 tablets lasts 50 days.

Can you take spirulina in the evening?

Yes. The label only says to take spirulina preferably during or just after a meal. The best time has not been studied, so dinner is just as good as breakfast.

How long can you use spirulina?

The directions are meant per day and do not mention a maximum duration. Most studies lasted 2 to 16 weeks, so less is known about use over many years. Choose a product with a certificate of analysis and talk to your GP if in doubt.

Can you take spirulina and chlorella on the same day?

Yes, you can. Stick to the daily dose on the label of each product and add up the spirulina from all products.

Sources

1. ANSES. Compléments alimentaires à base de spiruline: privilégier les circuits d'approvisionnement les mieux contrôlés (opinion 2014-SA-0096), 30 November 2017. anses.fr
2. Machowiec P, Ręka G, Maksymowicz M, Piecewicz-Szczęsna H, Smoleń A. Nutrients. 2021;13(9):3054. doi:10.3390/nu13093054 (meta-analysis, 5 studies, 230 participants)
3. Hariri M, Azizi-Soleiman F, Baradaran HR, Heshmati M, Gholami A. Int J Vitam Nutr Res. 2026;96(1):44330. doi:10.31083/IJVNR44330 (meta-analysis, 8 studies)
4. Packaging texts and product pages of Spirulina Tablets, Spirulina Powder, Spirulina Chlorella Tablets and Daily Greens, consulted 5 November 2026.

You can find all our spirulina, on its own or combined with chlorella, on the page buy spirulina.

This article is for information only and is not medical advice. Food supplements are not a substitute for a varied and balanced diet and a healthy lifestyle. If in doubt, pregnant or taking medication, talk to your GP or pharmacist.