Evidence supporting the use of: Spirulina
For the health condition: Cold Sores

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Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Spirulina, a blue-green algae, has been investigated for its antiviral properties, including activity against herpes simplex virus (HSV), the cause of cold sores. Several laboratory studies have demonstrated that extracts from Spirulina platensis can inhibit the replication of HSV-1 in vitro. These effects are attributed mainly to a sulfated polysaccharide component called calcium spirulan, which appears to block viral entry into host cells. For example, a study published in Antiviral Research (Hayashi et al., 1996) found that calcium spirulan could inhibit HSV-1 infection in cell cultures. Subsequent research has supported these findings, indicating a potential antiviral role for spirulina components against HSV.

However, while laboratory data is promising, evidence in humans remains lacking. There are no published clinical trials that directly assess spirulina’s effectiveness in preventing or treating cold sores in people. Most of the current evidence is preclinical and does not address issues such as dosage, safety, or efficacy in real-world use. Spirulina is not a traditional remedy for cold sores in folk medicine, so its use is based on modern scientific exploration rather than historical practice. In summary, laboratory studies suggest a possible benefit, but clinical validation is absent, warranting a moderate-low evidence score.

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