The European Union law aims to protect consumers from possible damaging side-effects of over-the-counter herbal medicines.
For the first time, new regulations will allow only long established and quality controlled medicines to be sold.
However, both herbal remedy practitioners and manufacturers fear they could be forced out of business.
To date, the industry has been covered by the 1968 Medicines Act, drawn up when only a handful of herbal remedies were available and the number of herbal practitioners was very small.
Meanwhile, surveys show that about a quarter of all adults in the United KingdomÂ have used herbal medicine in the past two years, mostly bought over the counter in health food shops and pharmacies.