"Till proper research results come let us not distribute Nilavembu concoction," the actor tweeted. Mr Haasan said he does not like his fans taking medicines without prescriptions from doctors.
"Only for this reason I tweeted against (the concoction). I'm only critical of giving medicine without doctor's advice. Dengue control lessons could be learnt from neighbouring Kerala," the actor said.
The Indian Medical Association has also demanded scientific evidence of the concoction's benefits. "Hundreds of herbal plants have become a part of allopathy with scientific evidence. But without evidence how can the government keep saying Nilavembu cures dengue?" said Dr T N Ravisankar, state head of the association.
The Tamil Nadu government insists the age-old herbal concoction is a sure cure with its anti-viral properties. Dr K Kolandasamy, Director of Public Health and Preventive Medicine, said, "There's tacit knowledge, for thousands of years our ancestors have huge knowledge. If you ask of scientific evidence, how come several drugs get banned after being used for several years?"
The authorities say many patients who died of dengue were reported to hospitals in a late stage when the disease had already taken complete hold of the patients.
Under severe criticism for failing to check dengue outbreak and hospitals crowded with patients, officials promoted the herbal concoction as a simple solution to check this viral fever.