Health bosses in Yorkshire say bad weather has caused problems in delivering an anti-viral drug used to treat swine flu.
The strategic health authority has moved to reassure patients that stocks will be available after one patient, from Golcar in Huddersfield, was unable to get Tamiflu from chemists in the town.
A spokesperson from NHS Yorkshire and the Humber said bad weather had caused some difficulty in delivering to some pharmacy wholesalers and they were working with the manufacturer to rectify it.
Manufacturer Roche said it had seen a sudden increase in demand for the drug in recent days and had sufficient stock available to meet demand for its various capsules.
The firm said major distributers AAH Pharmaceuticals Ltd and Alliance Healthcare Ltd were taking in stock into each of their depots but it warned that stocks of Tamiflu powder, which is dissolvable in water and can be used for children and patients who are too ill to swallow a tablet, were "severely limited".
It has advised that this form of the drug should be prioritised for use for children and because of low stock it is only being directed to hospitals.
Seventeen people have died from flu so far this winter.
Latest figures from the Health Protection Agency (HPA) revealed that 14 deaths were from swine flu and another three from flu type B. Both types are included in the current vaccination programme and the Government is urging all those in "at-risk groups", such as those with heart or respiratory disease, to be vaccinated.
A pregnant woman in Nottingham is fighting for her life in hospital after contracting the disease.
Mother-of-four Fallon Devaney, 25, had been suffering from flu symptoms for more than a week, her mother said, and was rushed to the Queen's Medical Centre in Nottingham after struggling for breath.
Miss Devaney, who is five months pregnant, is being treated in intensive care.