Chao Phraya Abhaibhubejhr Hospital issued the warning after seeing soaring demand for the herbal extract from people who believe it can protect them from Covid-19.
People are rushing to buy fah talai jone after the Department of Thai Traditional and Alternative Medicine recently announced that the Thai herb had cured more than 300 Covid-19 patients of mild symptoms.
Since the first wave of Covid-19 emerged in Thailand, certain hospitals including Chao Phraya Abhaibhubejhr have been using fah talai jone together with other medicines to treat Covid-19 patients. The patients have reportedly recovered without side effects.
Last December, the Public Health Ministry approved the use of fah talai jone to treat early-stage Covid-19.
However, Thai experts warn there is no solid scientific evidence that fah talai jone can boost immunity or relieve the symptoms of Covid-19.
The herbal extract has been used for centuries in Asia to combat flu and related diseases.
Chao Phraya Abhaibhubejhr Hospital added that research indicated the herb can help prevent flu if consumed in low amounts continually for three months.
A medic at the hospital said fah talai jone boosted immunity.