As the dispute between pharmacists and the Health Service Executive over reduced payments continues for a fifth day, a leading consultant neurologist has claimed that patients' lives may be put at risk.
Dr Norman Delanty of Beaumont Hospital said people with epilepsy must get their correct medication.
Patient support groups representing people with epilepsy, diabetes and the elderly have today expressed concern about the impact of the pharmacy dispute.
The Irish Epilepsy Association said that 37,000 people with epilepsy secure their medicines on the long-term illness scheme and while most would have stocked up for four weeks, a serious situation could arise if the dispute is not resolved soon.
The Diabetes Federation of Ireland said there was 'utter confusion' among patients about which pharmacies were open.
While its members would usually have insulin supplies for a month, the organisation said that a long dispute could be very serious.
Age Action Ireland said the row was particularly affecting older people in rural areas.
The organisation said that some pharmacies which have not withdrawn from State schemes appeared to have shortened their opening hours.
Boots Pharmacy, which is not involved in the dispute, said all emergency prescriptions are being taken care of but all non-emergency prescriptions will be available within 48 hours.
Boots Pharmacy in Swords, Co Dublin, has told customers it can only start filling non-urgent prescriptions again on Friday.
It said the decision had been taken due to unprecedented demand today and for patients' safety.
The pharmacy said it will try to fill urgent prescriptions today from customers.
It is understood the Boots in Waterford finished dispensing to all patients at lunchtime today and will resume at 8.30am tomorrow.
Earlier, the Health Service Executive said it had written to a number of pharmacies saying it is preparing to apply for High Court injunctions to force them to comply with their State contracts.
The Executive claims that a small number of pharmacies that hold contracts to dispense State drugs have closed, partially closed or are refusing to accept new customers.
Hundreds of pharmacies withdrew from the medical card scheme on Saturday in protest at the decision to unilaterally reduce their fees.
The HSE also said that only 'a very small number of people' have accepted the offer of free transport to collect prescriptions from pharmacies or the alternative emergency dispensaries it has established in local health centres and clinics in the western region.
Nine of these emergency outlets have been opened so far, but the HSE says it is not now going ahead with plans to open a tenth in Ballina, Co Mayo.
The HSE says it is willing to provide transport to the nearest participating pharmacy to ensure that no patient in urgent need of medication is left without it.
Labour Party Health Spokesperson Jan O'Sullivan today repeated her call for Health Minister Mary Harney to find a resolution to the dispute.