Excuse me, is the medical sage Bitongkang a fake medicine? What are the side effects?

It's not fake. Maybe your grandmother is not suitable for taking this medicine, because not every medicine is effective for every patient, but most of them are effective. Some medicines and foods are homologous, and they can also achieve therapeutic effects. My mother also used Yisheng Bitongkang, and she told me that the effect was ok. Now the swollen foot is gone, and it doesn't hurt anymore. It's been almost half a year since I stopped taking the medicine, and there has been no recurrence.