Users of St John's Wort, a herbal product used to treat depression, have begun stockpiling supplies ahead of the Government's ban on its over-the-counter sale, which begins tomorrow.
Shops selling St John's Wort have reported customers buying up to four times their normal quantity. From tomorrow new legislation will make the herbal treatment a prescription-only product.
"Although we are discouraging bulk-buying, people are feeling very anxious about its withdrawal," a Health Products Alliance spokeswoman, Ms Erica Murray, said.
"Customers are buying double, and in some cases four times, their normal quantity of St John's Wort. We are having to check that the product is going to be used before its sell-by date expires."
The Minister for Health and Children, Mr Cowen, signed the statutory instrument making St John's Wort a prescription-only product following a recommendation by the Irish Medicines Board. The board was concerned about the potential side-effects of the herbal treatment.
The Irish Green MEP, Ms Nuala Ahern, has already complained about the move to the EU Commissioner for the Internal Market, Mr Frederick Bolstein, claiming that the product is available elsewhere in the EU and the IMB move is contrary to the workings of the internal market. The commissioner is currently investigating the situation.
The Health Products Alliance, which represents retailers and wholesalers of alternative health products, will meet in the coming weeks to decide its response to the ban.
The IMB intends to begin enforcing the prescription-only ruling next week.
An estimated 75,000 people are believed to be using St John's Wort in the Republic for the treatment of mild or moderate depression.
Ms Murray said Alliance members were reminding their customers that the herbal product was still available in Northern Ireland and abroad, and could be purchased over the Internet.