The Tamil Nadu government is promoting the Nilavembu herbal concoction as a magic potion that will prevent dengue. The disease has killed over 40 people across the state. Actor Kamal Haasan, however, has tweeted asking his fans to not distribute the Nilavembu concoction till it is tested for its efficacy. "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.