Blue-Green Algae

Blue-green Algae
Blue-green Algae

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for BLUE-GREEN ALGAE are as follows:

Possibly effective for…

Insufficient evidence to rate effectiveness for…

  • Hay fever. Early research shows that taking blue-green algae by mouth might relieve some allergy symptoms in adults.
  • Insulin resistance caused by drugs used to treat HIV/AIDS (antiretroviral-induced insulin resistance). Early research shows that taking blue-green algae by mouth increases insulin sensitivity in people with insulin resistance due to HIV/AIDS medication.
  • Arsenic poisoning. Early research shows that taking blue-green algae and zinc by mouth twice daily reduces arsenic levels and the effects of arsenic on the skin in people living in areas with high arsenic levels in the drinking water.
  • Athletic performance. The effect of blue-green algae on athletic performance is unclear. An early study shows that men who jog regularly are able to sprint for longer periods of time before becoming tired when they take it. However, another early study shows that taking it does not improve calories burned while exercising on an elliptical trainer machine.
  • Attention deficit-hyperactivity disorder (ADHD). Early research shows that taking blue-green algae with a combination of herbs might improve ADHD scores in previously untreated children. But it’s not clear if this is from the algae, the other herbs, or the combination.
  • Tics or twitching of the eyelids (blepharospasm). Early research shows that taking blue-green algae does not reduce eyelid spasms in people with blepharospasm.
  • Diabetes. Early research shows that taking blue-green algae by mouth might improve cholesterol levels by a small amount.
  • Fatigue. Early research shows that taking it by mouth does not improve fatigue in adults with long-term complaints of fatigue.
  • Hepatitis C. Research on the effects of blue-green algae in people with chronic hepatitis C has been inconsistent. One study shows that taking it by mouth results in greater improvements in liver function compared to milk thistle in adults with hepatitis C who were not yet treated or were unresponsive to other treatments. However, another study shows that taking blue-green algae worsens liver function in people with hepatitis C or hepatitis B.
  • HIV/AIDS. Research on the effects of blue-green algae in people with HIV/AIDS is mixed. Some early research shows that taking it by mouth reduces infections, stomach, and intestinal problems, feelings of tiredness, and breathing problems in patients with HIV/AIDS. However, taking it does not appear to improve CD4 cell counts or reduce viral load in HIV patients.
  • High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). Early research shows that blue-green algae lower cholesterol in people with normal or slightly elevated cholesterol levels. However, the research findings have been somewhat inconsistent. In some studies, it only lowers low-density lipoprotein (LDL or “bad”) cholesterol. In other studies, it lowers total cholesterol and LDL cholesterol, and increase high-density lipoprotein (HDL or “good”) cholesterol.
  • A condition caused by a poor diet or the body’s inability to absorb nutrients. Early research on the use of blue-green algae in combination with other dietary treatments for malnutrition in infants and children shows conflicting results. Weight gain was seen in undernourished children who were given spirulina with a combination of millet, soy, and peanut for 8 weeks. However, in another study, children up to 3 years-old who were given the algae daily for 3 months did not gain weight more than those given general treatments to improve nutrition alone.
  • Symptoms of the menopause. An early study shows that taking blue-green algae by mouth lowers anxiety and depression in women going through menopause. However, it doesn’t appear to reduce symptoms such as hot flashes.
  • Mental alertness. An early study shows that taking blue-green algae improves feelings of mental tiredness and scores on a mental math test.
  • Obesity. Research on the effects of blue-green algae in people who are overweight or obese is unclear. Some early research shows that taking it by mouth slightly improves weight loss in overweight or obese adults. In addition, some early research shows that taking it might improve levels of cholesterol in obese adults. But other studies show no weight loss with it.
  • White patches inside the mouth are usually caused by smoking (oral leukoplakia). Early research shows that taking blue-green algae by mouth reduces mouth sores in people who chew tobacco.
  • A serious gum infection (periodontitis). Early research shows that injecting a gel containing blue-green algae into the gums of adults with gum disease improves gum health.
  • Anxiety.
  • Low levels of healthy red blood cells (anemia) due to iron deficiency.
  • Premenstrual syndrome (PMS).
  • Cancer.
  • Build-up of fat in the liver in people who drink little or no alcohol (nonalcoholic fatty liver disease or NAFLD).
  • Depression.
  • Stress.
  • Fatigue.
  • Indigestion (dyspepsia).
  • Heart disease.
  • Memory.
  • Wound healing.
  • Other conditions.

More evidence is needed to rate the effectiveness of blue-green algae for these uses.

Side Effects Of Blue-Green Algae

When taken by mouth: Blue-green algae products that are free of contaminants, such as liver-damaging substances called microcystins, toxic metals, and harmful bacteria, are POSSIBLY SAFE for most people when used short-term. Doses up to 19 grams per day have been used safely for up to 2 months. Lower doses of 10 grams per day have been used safely for up to 6 months. Side effects are typically mild and may include nausea, vomiting, diarrhea, abdominal discomfort, fatigue, headache, and dizziness.

But blue-green algae products that are contaminated are POSSIBLY UNSAFE. Contaminated algae can cause liver damage, stomach pain, nausea, vomiting, weakness, thirst, rapid heartbeat, shock, and death. Don’t use any blue-green algae product that hasn’t been tested and found to be free of microcystins and other contamination.

Warnings & Precautions Of Blue-Green Algae

  • Pregnancy and breast-feeding: There isn’t enough information available to know if it is safe to use when pregnant or breast-feeding. Contaminated products contain harmful toxins that might be transferred to an infant during pregnancy or through breast milk. Stay on the safe side and avoid use.
  • Children: Blue-green algae are POSSIBLY UNSAFE for children. Children are more sensitive to contaminated algae products than adults.
  • Auto-immune diseases such as multiple sclerosis (MS), lupus (systemic lupus erythematosus, SLE), rheumatoid arthritis (RA), pemphigus Vulgaris (a skin condition), and others: Blue-green algae might cause the immune system to become more active, and this could increase the symptoms of auto-immune diseases. If you have one of these conditions, it’s best to avoid using.
  • Bleeding disorders: Blue-green algae might slow blood clotting and increase the risk of bruising and bleeding in people with bleeding disorders.
  • Diabetes: Blue-green algae might affect blood sugar levels. Watch for signs of low blood sugar (hypoglycemia) and monitor your blood sugar carefully if you have diabetes and use it.
  • Phenylketonuria: The spirulina species of blue-green algae contains the chemical phenylalanine. This might make phenylketonuria worse. Avoid Spirulina species products if you have phenylketonuria.
  • Surgery: Blue-green algae might lower blood sugar levels. There is some concern that it might interfere with blood sugar control during and after surgery. Stop using it at least 2 weeks before a scheduled surgery.


Consult your doctor or pharmacist.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.